NETA Handbook Series I, Arc-Flash Vol 1-PDF

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Published by InterNational Electrical Testing Association

Arc Flash Safety Handbook Volume 1

Published by InterNational Electrical Testing Association

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Arc Flash Safety Handbook — Volume 1

Table of Contents High Voltage Safe Work Practices ...................................................................................................... 1 Paul Hartman

Electrical Hazard Analysis Changing Standards and Changing Attitudes ........................................... 5 Ray Harold

Approach Boundaries ........................................................................................................................ 7 John Cadick, P.E.

NFPA 70E 2000 Update ...................................................................................................................... 9 John Cadick, P.E.

Protective Devices Maintenance as it Applies to the Arc/Flash Hazard ............................................ 16 Dennis K. Neitzel, C.P.E.

Electric Arc Flash Protective Clothing .............................................................................................. 19 Paul Hartman

Corrective Measures to Arc Flash Problems — Is It that Simple? .................................................... 22 Ron Widup

Electrical Safety — Myths and Rumors ............................................................................................ 26 David K. Kreger

Arc Flash Concerns .......................................................................................................................... 29 Conrad St. Pierre

Six Steps to Arc Flash Nirvana ......................................................................................................... 35 Jim White

Arc Flash Hazards to Be Studied ....................................................................................................... 41 Ron Widup and Jim White

Electrical Hazards Analysis .............................................................................................................. 42 Dennis K. Neitzel, C.P.E

Electrical PPE Trends ....................................................................................................................... 47 Bill Rieth

Proper PPE — A Journey with No End: One Company’s Experiences ............................................... 49 Tony Demaria

Arc Flash Safety Handbook — Volume 1

Table of Contents Empowering Safety — Part I ............................................................................................................ 51 Charlie Simpson

Do I Have to Comply with NFPA 70E? ............................................................................................. 54 Lynn Hamrick

Empowering Safety — Part 2 ........................................................................................................... 58 Charlie Simpson

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Arc Flash Safety Handbook — Volume 1

High Voltage Safe Work Practices PowerTest 2000 (NETA Annual Technical Conference) Paul Hartman Electro-Test, Inc.

The majority of information used to assemble this paper came from two sources, NFPA 70E (Standards for Electrical Safety Requirements for Employee Workplaces) and the OSHA Safety Regulations. For all practical purposes and discussions objects that are not insulated for the voltage being worked on must be considered conductive.

An important aspect of working safely around electrical equipment is to follow the rules associated with working clearances. These working clearances assist in setting up an environment that will help prevent personnel contact with energized circuits and to minimize hazards in the event of an arc/blast.

Job Analysis

According to NFPA, 70E flash hazard analysis shall be done before a person approaches any exposed electrical conductor or circuit part that has not been placed in an electrically safe work condition. In certain instances, the flash protection boundary (distance at which curable burns will occur during a blast) might be a greater distance than the limited approach boundary (distance for preventing electrical shock). The greater distance shall be utilized to trigger the need for personal protective equipment. Figure 1 identifies the flash protection boundary distance for exposed electrical components.

Prior to any work being performed employees must determine whether equipment in the area where work is to be performed will be energized or de-energized. Once the status of the electrical equipment is identified proper working clearances must be maintained.

Working Clearances Below 600 Volts Sufficient access and working space shall be provided and maintained around electrical equipment to permit safe operation and maintenance of such equipment. NFPA 70E states that a minimum of three (3) feet is required in front of equipment rated 0-150 volts to ground. This is to ensure that any access to energized equipment requiring examination, adjustment servicing, or maintenance will provide the worker with adequate work space. For voltages between 151-600 volts to ground, a three (3) foot clearance is still required between exposed live parts and other surfaces. If the other surfaces are grounded, then the distance must be increased to three and a half (3-1/2) feet. If there are exposed live parts on either side of the workspace, then a distance of four (4) feet is required.

Working Clearances Above 600 Volts For voltages greater than 600 volts to ground the minimum clearance depth in front of switchgear varies from 3 feet to 12 feet depending on the voltage and proximity to other equipment. The details for determining the proper distances are outline in section 1 of NFPA 70E.

Flash Protection Distances

FLASH PROTECTION BOUNDARY

Phase to Phase Voltage

Distance From Equipment

300 V and less

3 ft 0 in

Over 750 V, not over 2 kV

4 ft 0 in

Over 300 V, not over 750 V

3 ft 0 in

Over 2 kV, not over 15 kV

16 ft 0 in

Over 36 kV, not over 800 kV

*

Over 15 kV, not over 36 kV

19 ft 0 in

* For values above 36 kV, calculate the distance by using the formula in figure 2 Figure 1 — Flash protection distances

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Arc Flash Safety Handbook — Volume 1 CURABLE BURNS BOUNDARY

DISTANCE FROM ELECTRICAL EQUIPMENT 1/2

Dc = ( 2.65 x MVAbf x t ) 1/2

Dc = ( 53 x MVA x t )

Where: Dc

or

= Distance of a person from an arc source for a just curable burn, in feet.

MVAbf = bolted afult MVA at point involved.

MVA = MVA rating of transformer. For transformers with MVA rating below 0.75 MVA, multiply the transformer MVA rating by 1.25. t

= time of arc exposure in seconds.

Figure 2 — Formula for calculating flash distances

Safe Switching Practices A high percentage of accidents occur during switching operations. The following is a suggested switching sequence:

• Secure authorization before performing any switching, preferably in writing or as a part of a Standard Operating Plan (SOP).

• Review one-line diagram to identify equipment affected by the switching operation.

Limited Approach Boundary The NFPA 70E guidelines for approach distance for unqualified personnel to exposed energized conductors are shown in figures 3 and 4. When workers without electrical training are working on the ground or elevated position near overhead lines, the location shall be such that the person and the longest conductive object that a person might contact cannot come close to any unguarded, energized overhead line that has not been placed into an electrically safe work condition (figure 3). LIMITED APPROACH BOUNDARY EXPOSED MOVABLE CONDUCTOR

Phase to Phase Voltage 300 V and less

Over 300 V, not over 72.5 kV

Over 72.5 kV, not over 121 kV Over 138 kV, not over 145 kV Over 161 kV, not over 169 kV Over 230 kV, not over 242 kV Over 345 kV, not over 362 kV Over 500 kV, not over 550 kV Over 765 kV, not over 800 kV

Distance, Energized Part to Employee 10 ft 0 in 10 ft 0 in 10 ft 8 in 11 ft 0 in 11 ft 8 in 13 ft 0 in 15 ft 4 in 19 ft 0 in 23 ft 9 in

Figure 3 — Unqualified personnel minimum approach distance to a movable conductor

• All personnel affected by the switching operation should be notified.

When an unqualified worker is working near stationary exposed conductors the location shall be such that they or the longest conductive object does not get within the limited approach boundary (figure 4).

• Personal protective equipment should be worn. Hard hat, eye glasses or face shield, proper gloves, and longsleeved protective (cotton or nomex) coveralls are recommended as a minimum. Blast suites are required on high-energy circuits.

LIMITED APPROACH BOUNDARY

• Once the worker is prepared to operate the switch, it should be operated as if it may fail. This implies some precautions to be taken:

• Identify the immediate blast zone. If the switch fails, where will the blast go? If you cannot operate the device remotely, stand off to the side that offers the most protection from an anticipated blast.

EXPOSED FIXED CONDUCTOR

Phase to Phase Voltage 300 V and less

Over 300 V, not over 750 V Over 750 V, not over 2 kV

Over 2 kV, not over 15 kV

Distance, Energized Part to Employee 3 ft 6 in 3 ft 6 in 4 ft 0 in 5 ft 0 in

• Have a backup person who can render assistance if necessary, but make sure they stay out of the immediate blast zone.

Over 15 kV, not over 36 kV

Over 138 kV, not over 145 kV

10 ft 0 in

• Make sure panel covers and doors are secure.

Over 230 kV, not over 242 kV

13 ft 0 in

• Keep all others out of the switching area.

• Before re-energization, verify that all locks and tags have been removed and the circuit has been visually inspected and tested safe for re-energization.

Over 36 kV, not over 121 kV

Over 161 kV, not over 169 kV Over 345 kV, not over 362 kV Over 500 kV, not over 550 kV Over 765 kV, not over 800 kV

6 ft 0 in 8 ft 0 in

11 ft 8 in 15 ft 4 in 19 ft 0 in 23 ft 9 in

Figure 4 — Unqualified personnel minimum approach distance to a stationary conductor

Arc 1 Flash Safety Handbook — Volume 1 OSHA — Ten Foot Rule OSHA specifies a minimum clearance from energized 50 kV power lines of 10 feet fro all unqualified workers. This is known as the “10-foot rule.” For voltage levels above 50 kV an additional four inches for every 10 kV above 50 kV shall be added to the 10’ clearance requirement. A visual representation of the “Ten-Foot Rule” is shown in figure 5.

Arc Flash Safety Handbook — Volume 1 3 point of work or where insulating barriers rated for the expected voltage have been erected to prevent physical contact with lines or other exposed electrical parts, mobile equipment in transit, with no load attached and boom lowered, shall observe the following minimum dimensional clearances: (1) 4 feet for voltages less than 50 kV.

(2) 10 feet for voltages over 50 kV, up to and including 345 kV. (3) 16 feet for voltages up to and including 750 kV.

(4) Where it is difficult for the operator to maintain the desired clearance by visual means, a person shall be designated to observe clearance as an aid to the operator.

Qualified Person Approach Distances No qualified persons shall approach or take any conductive object, without a suitable insulated handle, closer to exposed energized conductors or circuit parts than the distances listed in figure 6, “Restricted Approach Boundary.” RESTRICTED APPROACH BOUNDARY

STANDARD INADVERTENT MOVEMENT BOUNDARY Phase to Phase Voltage

300 V and less

Over 300 V, not over 750 V Over 750 V, not over 2 kV

Over 2 kV, not over 15 kV

Over 15 kV, not over 36 kV Figure 5 — Illustration of the ten-foot rule as it applies to substations and overheard lines

Vehicular and Mechanical Equipment Where is could reasonably be anticipated that parts of any vehicle or mechanical equipment structure will be elevated near energized overhead lines, they shall be operated so that the limited approach boundary distance of figure 3 is maintained. There are exceptions to this rule for when a vehicle is in transit, or the conductors are insulated, or the equipment is designed to be insulated against the voltage being worked on. The reduced clearances for specific applications, outlined in Section 2 of NFPAA 70E, should be reviewed prior to performing work.

Mobile Equipment in Transit Except where electrical distribution and transmission lines have been de-energized and visibly grounded at the

Distance, Energized Part to Employee Avoid Contact 1 ft 0 in 2 ft 0 in 2 ft 2 in 2 ft 7 in

Over 36 kV, not over 48.3 kV

2 ft 10 in

Over 72.5 kV, not over 121 kV

3 ft 5 in

Over 48.3 kV, not over 72.5 kV Over 138 kV, not over 145 kV Over 161 kV, not over 169 kV Over 230 kV, not over 242 kV Over 345 kV, not over 362 kV Over 500 kV, not over 550 kV Over 765 kV, not over 800 kV

3 ft 3 in 3 ft 7 in 4 ft 0 in 5 ft 3 in 8 ft 6 in

11 ft 3 in

14 ft 11 in

Figure 6 — Restricted approach distances

No qualified person shall approach or take any conductive object without a suitable insulated handle closer to exposed energized electrical conductors or circuit parts than the restricted approach boundary unless: (a) The qualified person is insulated or guarded from the energized conductors or circuits parts and no unguarded part of the person’s body enters into the prohibited space identified in figure 7.

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Arc Flash Safety Handbook — Volume 1

(b) The energized conductor or circuit part is insulated or guarded from all conductive objects at a potential different from that of the energized part.

(c) The qualified person is isolated, insulated, or guarded from all conductive objects at a potential different form that of the energized part. Any variation from the requirements of (a), (b), or (c) above requires additional hazard/risk analysis. PROHIBITED APPROACH BOUNDARY

REDUCED INDAVERTENT MOVEMENT BOUNDARY Phase to Phase Voltage

300 V and less

Over 300 V, not over 750 V Over 750 V, not over 2 kV

Over 2 kV, not over 15 kV

Distance, Energized Part to Employee Avoid Contact 0 ft 1 in 0 ft 3 in 0 ft 7 in

Over 15 kV, not over 36 kV

0 ft 10 in

Over 48.3 kV, not over 72.5 kV

2 ft 1 in

Over 36 kV, not over 48.3 kV

Over 72.5 kV, not over 121 kV Over 138 kV, not over 145 kV Over 161 kV, not over 169 kV Over 230 kV, not over 242 kV Over 345 kV, not over 362 kV Over 500 kV, not over 550 kV Over 765 kV, not over 800 kV

1 ft 5 in 2 ft 8 in 3 ft 1 in 3 ft 6 in 4 ft 9 in 8 ft 0 in

10 ft 9 in 14 ft 5 in

Figure 7 — Prohibited approach distances

Access Requirements The entrances to all buildings, rooms, or enclosures containing exposed live parts or exposed conductor operating at over 600 volts, nominal, shall be kept locked or shall be under the observation of a qualified person at all times.

Installations Accessible to Unqualified Persons Electrical installations that are open to unqualified persons shall be made with metal-enclosed equipment or shall be enclosed in a vault or in an area, access to which is controlled by a lock. Metal enclosed switchgear, unit substations, transformers, pull boxes, connection boxes, and other similar associated equipment shall be marked with appropriate caution signs. Ventilation or similar openings in metal-enclosed equipment shall be designed so that foreign objects inserted through these openings will be deflected away from energized parts.

Paul Hartman is a NETA Certified Senior Technician/Level IV working as a field engineer and instructor for the ETI Learning Center, a division of Electro-Test, Inc., a NETA Full Member. He is a regular contributor to NETA World and to the Annual Technical Conference.

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Arc Flash Safety Handbook — Volume 1

Electrical Hazard Analysis Changing Standards and Changing Attitudes NETA World, Summer 2000 Issue by Ray Harold, Senior Training Specialist AVO Training Institute

The petrochemical industry and many government institutions have performed research on the subject of electrical hazards for over twenty years. For the most part, however, the electrical industry, at least at the user level, has largely ignored the subject — essentially reacting to catastrophic accidents rather than proactively trying to predict and prevent them. Recent changes in consensus standards, along with a better general understanding of the seriousness of electrical hazards, has resulted in a renewal of interest in the subject. This article provides an overview of the three principle types of electrical hazard analysis along with a discussion of the relevant standards and regulations pertaining to the subject.

Shock Hazard Analysis Each year several hundred workers are killed as a result of inadvertent contact with energized conductors. Surprisingly, over half of those killed are not traditionally in electrical fields (i.e., linemen, electricians, technicians). Recent investigations into the causes of these fatalities point to three principle causal factors: 

 

Failure to properly or completely de-energize systems prior to maintenance or repair work. Intentionally working on energized equipment.

Improper or inadequate grounding of electrical system components.

These factors form the basis for analysis of the electrical shock hazard. To appropriately assess the electrical shock hazard associated with any type of maintenance or repair work, it is necessary to evaluate procedures or work practices that will be involved. These practices should be evaluated against both regulatory requirements and recognized good practice within the industry. These principles are summarized below.

Regulatory Requirements 







All equipment must be placed in a de-energized state prior to any maintenance or repair work. (Limited exceptions exist.)

The de-energized state must be verified prior to any work. The de-energized state must be maintained through the consistent use of locks and tags. When energized work is performed, it must be performed in accordance with written procedures.

Industry-Recognized Good Practice  

Plan every job.

Anticipate unexpected results.

Use procedures as tools.

  

Identify the hazards.

Assess employees’ abilities.

In addition to the assessment of work practices and procedures against these principles, shock hazard analysis must include an assessment of the physical condition of the electrical system. Although the continuity and low resistance of the equipment grounding system is a major concern, it is not the only one. Of equal importance is the assurance that covers and guards are in place, access to exposed conductors is limited to electrically qualified personnel, and overcurrent protective devices are operable and of appropriate rating. Even the safest procedures performed on poorly constructed or maintained facilities represent a risk to employees.

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Arc Flash Safety Handbook — Volume 1

Flash Hazard Analysis An estimated 75 to 80 percent of all serious electrical injures are related to electrical arcs created during short circuits and switching procedures. In recognition of this fact, standards organizations such as the National Fire Protection Association (NFPA) have attempted to provide the industry with better techniques to evaluate both the magnitude of the electrical arc hazard and appropriate protective clothing. An electrical arc is basically an electrical current passing through ionized air. This current flow releases a tremendous amount of energy as both radiated light and convected heat. The amount of liberated energy is obviously dependent upon the system configuration, but the principle factors used in the determination of the hazard to personnel are as follows:    

Available short-circuit current at the arc location Duration of the electrical arc

Distance from the arc to personnel

Environmental conditions and surroundings at the arc location.

To accurately assess the arc hazard and make appropriate decisions regarding protective clothing, it is necessary to fully understand the operation of the system under fault conditions. This requires both a short-circuit study, in all likelihood down to the panelboard level, and a coordination study. With this information available, the magnitude of the arc hazard at each work location can be assessed using several techniques. These techniques include: 





Tables and equations (published by various sources, including NFPA 70E)

Freeware – authored by Duke Power and available on the internet Commercial software – available from Ontario Hydro Technologies

Each of these techniques requires an understanding of anticipated fault conditions and the limitation of the calculation method, both of which are beyond the scope of this article. The results of the arc hazard assessment are most useful when expressed in terms of the incident energy received by exposed personnel. Incident energy is commonly expressed 2 in terms of calories per cm . Arc protective clothing is rated in terms of its average thermal performance value 2 (ATPV), also expressed in terms of cal/cm . Thus, at least in theory, personnel can be protected by simply matching the protective clothing rating to the magnitude of the arc at a given location. While this technique sounds relatively straightforward, there is one problem. In some system configurations, particularly high-voltage utility type applications, no available clothing will provide sufficient protection for employees. In these cases, work practices used by employees, including clothing, tools, line clearance procedures,

and other factors, must be carefully scrutinized to insure the risk to employees is minimized. As with the electrical shock hazard, the easiest and most effective way to mitigate the arc hazard is to completely de-energize the system.

Blast Hazard Analysis An electrical blast or explosion, as it is often termed, is the result of the heating effects of an electrical arc. This phenomenon occurs in nature as the thunder that accompanies lightning, a natural form of an electrical arc. During an electrical arc, both the conducting material and the surrounding air are heated to extremely high temperatures. The resulting expansion of the air and vaporized conductive material creates a concussive wave surrounding the arc. The pressures in this wave may reach several hun2 dred lbf/ft , destroying equipment enclosures and throwing debris great distances. The blast hazard is analyzed in a manner similar to the arc hazard. The pressure created during an electrical explosion is directly proportional to the available short circuit at the arc location. With a current short-circuit study available, the anticipated blast pressure can be estimated from tables or charts. Unfortunately, little can be done to mitigate the blast hazard, at least in terms of personal protective clothing or equipment. Blast pressure calculations can be used to determine whether enclosures will withstand an internal fault, if sufficient manufacturer’s data is available. Again, it may be more important to merely recognize the magnitude of the hazard so appropriate safety practices, such as correct body positioning, can be incorporated into work procedures.

Conclusions Regulatory agencies and standards organizations have long recognized the need to analyze the hazards of electrical work and plan accordingly to mitigate the hazards. Unfortunately, many in the electrical industry have chosen to “take their chances” largely because nothing bad has happened yet. As more information becomes available on the economic and human costs of electrical accidents, it is hoped more people in the industry will recognize the need for systematic hazard analysis and an electrical safe work program that emphasizes hazard identification and abatement. Ray C. Harold, Senior Training Specialist for AVO International Training Institute, Dallas, Texas, earned his BS Degree in Electrical Engineering at Kansas State University, Manhattan, KS, graduating Cum Laude Graduate, Honors Program in 1983. He is a technical instructor at AVO with responsibilities in curriculum development, course presentations, and electrical safety inspections. He has fifteen years’ experience in commercial, industrial, and research-and-development environments as well as eight years of supervisory experience.

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Arc Flash Safety Handbook — Volume 1

Approach Boundaries NETA World, Winter 2000-2001 Issue by John Cadick, P.E. Cadick Corporation

As shown in Figure 1, NFPA 70E defines four different approach boundaries for personnel safety. Note that the flash boundary is shown as a dashed line because, as we will describe later, its actual location varies as a function of available short circuit duty.

The prohibited approach boundary is determined by referring to Table 2-1.3.4 on Page 51 of NFPA 70E. (2000 Edition).

Limited Boundary The limited boundary is for unqualified personnel. No unqualified person may approach any exposed energized conductor any closer than the limited approach boundary. The limited approach boundary is determined by referring to Table 2-1.3.4 in NFPA 70E - Page 51. (2000 Edition.) Note that in the 2000 Edition NFPA has added the concept of movable or fixed conductors. In 2000 edition unqualified workers may approach nonmoving conductors (fixed buswork for example) more closely than those which may move (overhead lines for example).

Restricted Boundary Generally, qualified persons are not allowed to approach exposed, energized conductors any closer than the restricted approach boundary unless they are wearing appropriate personal protective equipment (PPE) and they have a written, approved plan for the work they are to perform. They must break the restricted boundary only to the extent that is absolutely necessary to perform their work. The restricted boundary is determined using Table 2-1.3.4 in NFPA 70E - Page 51. (2000 Edition)

Prohibited Boundary Crossing the prohibited approach boundary (qualified personnel only) is considered the same as actually contacting the exposed energized part. In addition to the requirements for restricted boundary approach, personnel must perform a risk assessment before the prohibited boundary is crossed.

Figure 1 — NFPA 70E Approach Boundaries

Flash Protection Boundary The radiant energy released by an electric arc is capable of maiming or killing a human being at distances of up to ten or even twenty feet. In addition to radiant heat, the molten material and objects ejected by the electrical blast can also be lethal. The flash protection boundary is the closest approach allowed by qualified or unqualified persons without the use of arc protection PPE. For systems of under 600 volts ac) 70E sets up two possible ways to calculate the flash boundary. 1. For locations with a total fault exposure of less than 5000 ampere-seconds (fault current in amperes multiplied by clearing time in seconds), a flash boundary of four feet may be used.

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Arc Flash Safety Handbook — Volume 1

2. Above 5000 ampere-seconds, or under engineering supervision for all levels, the following formulas may be used: Dc = √2.65 x MVAbf x t (1) – or – Dc = √53 x MVA x t (2) Where: The flash boundary radius Dc = MVAbf = The bolted fault MVA at the point of exposure MVA = The maximum fault MVA from the transformer feeding the circuit T= The time of exposure (based on protective device operation) Equation 1 provides generally smaller distances. For voltage levels in excess of 600 volts, other formulas may be used. The flash boundary is defined as that distance 2 at which the worker is exposed to 1.2 cal/cm for exposures 2 of more than 0.1 seconds or 1.5 cal/cm for exposures of more than 0.1 seconds.

In Summary for Flash Boundary • When an energized conductor is exposed, absolutely no one may approach closer than the flash boundary without wearing appropriate arc protection. • The application of Equation 1 will provide the smaller flash boundaries. • Equation 1 may not be applied without an accurate, upto-date short circuit analysis at the point of exposure.

• If the flash boundary is smaller than the limited approach boundary, the limited approach boundary is the closest that unqualified persons may approach. A registered professional engineer and the founder and president of the Cadick Corporation, John Cadick has specialized for over three decades in electrical engineering, training, and management. His consulting firm, based in Garland, Texas, specializes in electrical engineering and training and works extensively in the areas of power system design and engineering studies, condition-based maintenance programs, and electrical safety. Prior to creating the Cadick Corporation and its predecessor Cadick Professional Services, he held a number of technical and managerial positions with electric utilities, electrical testing companies, and consulting firms. In addition to his consultation work in the electrical power industry Mr. Cadick is the author of Cables and Wiring, The Electrical Safety Handbook, and of numerous professional articles and technical papers.

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Arc Flash Safety Handbook — Volume 1

NFPA 70E 2000 Update NETA World, Fall 2001 Issue by John Cadick, P.E. Cadick Corporation

Since its first printing in 1981, NFPA 70E has served as a central staple for the establishment of electrical safety programs. Used by the Occupational Safety and Health Administration (OSHA) as the basis for federal electrical safety rules, 70E has consistently been at the leading edge of electrical safety program implementation. The release of the 2000 edition of this document includes some of the most sweeping changes that have occurred in electrical safety since Ralph Lee first released his seminal research papers. This article describes many of the key changes that are introduced in 70E 2000. Of particular interest are the methods for the calculation of flash boundaries and flash protection. These methods are based on significant research performed during the last half of the 1990s. This research is continuing into the new millennium; consequently, substantial changes and improvements in electrical safety are to be expected over the next ten Figure 1 — NFPA 70E 2000 years.

OSHA and NFPA 70E Two of the frequent questions received about NFPA 70E are, “Do we have to follow 70E?”and “Will OSHA enforce 70E?” Such questions are usually asked by someone who is trying to expend the minimum possible effort required under the law. These individuals realize that OSHA Subpart S is a more simple standard to follow. I respond in one or more of four basic ways: 1) We are trying to create a safe workplace, 2) OSHA used 70E as the starting place for Subpart S, 3) If you adopt it, OSHA will enforce it, and 4) OSHA is presently looking into adopting 70E by reference.

We are trying to create a safe workplace We must always remember that the OSHA rules are, by definition, minimum standards. While strict adherence to OSHA may improve electrical safety, such adherence does not guarantee optimum safety. For example, OSHA Subpart S says nothing about specific arc flash protection requirements, and even Subpart R is somewhat vague, referencing only what an employee is not allowed to wear. OSHA Subpart S has been introduced over a twenty-year period starting in 1981, with the most recent change being a major modification to paragraph 137 in 1994. NFPA 70E, on the other hand, is revised approximately every three years. This most recent revision, after five years, was a major one that incorporated a number of significant changes in technology and world-wide regulations. 70E will always provide the greatest level of protection for personnel and should be used regardless of the status of the OSHA rules. The OSHA Act makes it very clear that every employer must provide the maximum degree of electrical safety. As one very large mining firm puts it, “Zero incidents and beyond!!” Since 70E is the clear leader in electrical safety regulations, it just makes good common sense to adopt it for your company’s safety rules.

OSHA used 70E as the starting place for the Electrical Safety Work Practices Rule The first release of 1910-331 through 335 was almost a verbatim copy of Part II of NFPA 70E. From the beginning then, OSHA has made it clear that, at least by reference, they recognized the importance of 70E. In fact, OSHA maintains nonvoting membership on the NFPA 70E working group. This means that OSHA has at least some input to all of 70E’s provisions

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Arc Flash Safety Handbook — Volume 1

If you adopt it, OSHA will enforce it

Miscellaneous changes

Nothing is so dangerous as the failure to follow a safety procedure. During investigations, OSHA will often cite failure to follow an extant safety procedure. Even if the procedure is not one stated in the OSHA rules, if it is disobeyed, OSHA will cite it.

In general, the 2000 edition of 70E has been expanded enormously. The definitions section of the Introduction has been extensively edited, and numerous definitions have been added. Definitions for the various hazardous classifications have been reduced and/or moved to Part 1. A quick scan of the section reveals that modifications have been made to almost one-half of the total with many new ones being added. Of particular interest is the addition of the definitions for approach boundaries. The limited, restricted, and prohibited approach boundaries are clearly defined. Calculating them is covered in Part 2 and the Appendices for Part 2.

OSHA is presently looking into adopting 70E by

reference

NFPA has submitted a written request to OSHA asking that NFPA 70E be adopted by reference. OSHA has responded by indicating their interest and asking the NFPA • Add more detail to their request. • Compile incident data which supports OSHA’s adoption of 70E. • Encourage industry and allied agencies to support the request. The 70E task group has responded by • Formulating a comparison between 70E and OSHA 1910 Subpart S and 1926 Subpart K. • Compiled incident data supporting OSHA’s adoption of 70E. • Soliciting letters of support from the electrical industry giants. So far four letters of support have been received and three more are promised. While nothing is certain at this point in time, OSHA has expressed a strong interest in adopting 70E by reference. This would mean that 70E becomes, in effect, the OSHA rules for electrical safety. Based on the arguments brought forth in this section, 70E should be your first choice for basis of an electrical safety program.

Significant changes to NFPA 70E 2000 edition 70E comprises six major parts: Foreword Introduction Part 1 Installation Safety Requirements Part 2 Safety-Related Work Practices Part 3 Safety-Related Maintenance Practices Part 4 Safety Requirements for Special Equipment Each of the parts comprises several chapters with Part 2 also having several appendices. The most important changes are those found in the Introduction and Parts 1 through 4.

Changes to Part 1 Part 1 of NFPA 70E covers the safety requirements for design and installation of electrical systems. It comprises six chapters. Chapters 1, 2, and 3 introduce general safety requirements such as suitability for purpose. Chapter 4 covers specific purpose equipment such as electric signs, cranes, elevators, and other such facilities. Chapters 5 and 6 cover hazardous locations in some detail. Note that all of Part 1 is based on the provisions of the National Electrical Code - NFPA 70. Chapter 1 Chapter 1 has been extensively edited since the 1995 edition. All of the sections are still essentially the same. Two paragraphs are of particular importance since they have not changed substantially. Paragraph 1-3.4 and 1-3.5 require that protected equipment be properly coordinated and that it be capable of interrupting the current to which it will be subjected. Chapter 2 This chapter covers wiring design and protection and has been expanded substantially with a great deal of detail being added in several places. Part 2.5, for example, covers overcurrent protection and has been modified dramatically in at least two places: 1. The under 600 volt protection requirements have been edited significantly. 2. The over 600 volt protection requirements have had almost one-half column of new requirements added since the last version. Chapters 3 and 4 The wiring methods, components, and equipment for general use chapter (Chapter 3) has been edited in 70 to 80 percent of its sections. The specific purpose equipment and installations chapter has also been modified although not as much as Chapter 3. It should be noted that the information covered in Chapter 4 addresses the installation and design safety requirements. The special equipment sections of Part 4 cover the special safety precautions required for systems such as batteries, cranes, and other apparatus.

11

Arc Flash Safety Handbook — Volume 1 Acceptable Equipment Comparison for Class I Locations Zone System Intrinsically safe, ia Equipment acceptable in Zone 0, Class I, Div. 1 Powder filled q Flameproof d Pressurized p Oil immersed o Increased safety e Intrinsically safe ib Encapsulation m

Zone 0

Zone 1

Equipment acceptable in Zone 0 Equipment acceptable in Zone 1, Class I, Div. 2 Zone 2 Non-sparking n Non-incendive Other electrical apparatus*

Division System

Division 1

Class I, Div. 1 Intrinsically safe i, ia

American standards gradually move toward and merge with the IEC standards. Chapter 6 Chapter 6 of Part 1 covers special systems such as medium- and high-voltage (over 600 volts), emergency systems, fire-alarm systems, and others. Glancing through this section shows that almost every paragraph has been extensively modified in the 2000 edition.

Changes to Part 2

Division 2

Class I, Div. 1 Class I, Div. 2 Flameproof d Pressurized p Intrinsically safe ib Oil immersed o Increased safety e Powder filled q Non-sparking n Encapsulation m Non-incendive Other electrical apparatus*

Arguably, the biggest changes throughout the entire document are found in Part 2. An enormous amount of research has been done in electrical safety-related work practices during the last decade of the 20th century. The principle examples of this research shows up in the calculation of approach distances and arc flash protection requirements. Approach Boundaries As shown in Figure 3, NFPA 70E defines four different approach boundaries for personnel safety. Note that the flash boundary is shown as a dashed line because, as I will

*”Other electrical apparatus” means electrical apparatus complying with the requirements of a recognized standard for industrial electrical apparatus that does not in normal service have ignition-capable hot surfaces and does not in normal service produce incendive arcs or sparks.

Figure 2 — Division vs. Zone method of hazardous locations

Chapter 5 Here we find some of the most important and sweeping changes in the 2000 edition of 70E. Installation requirements for hazardous locations have long been a source of confusion for electrical personnel. Now, as we enter the 21st Figure 3 — NFPA 70E Approach Boundaries century, the standards that have been used in the United States are being augmented by IEC (1) (2) (3) (4) (5) standards. Although a detailed coverage Limited Approach Boundary of these standards is beyond the scope of Restricted Approach this paper, Figure 2 illustrates some of the Boundary (Includes Prohibited Nominal System Exposed Moveable Exposed Fixed Inadvertent Approach key relationships between the Division Voltage (Ph-Ph) Conductor Conductor Movement) Boundary (NEC) and Zone (IEC) systems. This Not specified Not specified Not specified 0 to 50 Not specified table was presented and explained by Mr. 51 to 300 10 ft 0 in 3 ft 6 in Avoid contact Avoid contact Vince Rowe of Ramco Electrical Con301 to 750 10 ft 0 in 3 ft 6 in 1 ft 0 in 0 ft 1 in sulting Ltd. at the 2001 IEEE Electrical 751 to 15 kV 10 ft 0 in 5 ft 0 in 2 ft 2 in 0 ft 7 in Safety Workshop in Toronto Canada. 15.1 kV to 36 kV 10 ft 0 in 6 ft 0 in 2 ft 7 in 0 ft 10 in 36.1 kV to 46 kV 10 ft 0 in 8 ft 0 in 2 ft 9 in 1 ft 5 in In the 2000 Edition of 70E both the 46.1 kV to 72.5 kV 10 ft 0 in 8 ft 0 in 3 ft 3 in 2 ft 1 in NEC 70 Division method and the IEC 72.6 kv to 121 kV 10 ft 8 in 8 ft 0 in 3 ft 5 in 2 ft 8 in Zone method of hazardous location 138 kV to 145 kV 11 ft 0 in 10 ft 0 in 3 ft 7 in 3 ft 1 in classification are covered in detail. This is 161 kV to 169 kV 11 ft 8 in 11 ft 8 in 4 ft 0 in 3 ft 6 in consistent with the change that was made 230 kV to 242 kV 13 ft 0 in 13 ft 0 in 5 ft 3 in 4 ft 9 in in the 1999 NEC which allows the use of 345 kV to 362 kV 15 ft 4 in 15 ft 4 in 8 ft 6 in 8 ft 0 in either system in the United States. 500 kV to 550 kV 19 ft 0 in 19 ft 0 in 11 ft 3 in 10 ft 9 in In any event, this chapter has been 765 kV to 800 kV 23 ft 9 in 23 ft 9 in 14 ft 11 in 14 ft 5 in extensively modified and will probably be modified more in the future as the North Figure 4 — Approach boundaries (Table 2-1.3.4 from NFPA 70E 2000 Edition)

12

Arc Flash Safety Handbook — Volume 1

describe later, its actual location varies as a function of available short-circuit duty. The following paragraphs describe these changes. Limited Boundary The limited boundary is for unqualified personnel. No unqualified person may approach any exposed energized conductor any closer than the limited approach boundary. (Note that OSHA defines a qualified person as one who is familiar with and trained in the operation and safety hazards of the equipment that he is working on.) The limited approach boundary is determined by referring to Table 2-1.3.4 in NFPA 70E, page 51 (2000 Edition). This table is reproduced in Figure 4. Note that in the 2000 Edition NFPA has added the concept of movable or fixed conductors. In the 2000 edition unqualified workers may approach nonmoving conductors (fixed buswork, for example) more closely than those which may move (overhead lines, for example). Restricted Boundary Generally, qualified persons are not allowed to approach exposed, energized conductors any closer than the restricted approach boundary unless they are wearing appropriate personal protective equipment (PPE) and they have a written, approved plan for the work they are to perform. They must break the restricted boundary only to the extent that is absolutely necessary to perform their work. The restricted boundary is determined using Table 2-1.3.4 in NFPA 70E, page 51 (2000 Edition). Prohibited Boundary Crossing the prohibited approach boundary (qualified personnel only) is considered the same as actually contacting the exposed energized part. In addition to the requirements for restricted boundary approach, personnel must perform a risk assessment before the prohibited boundary is crossed. The prohibited approach boundary is determined by referring to Table 2-1.3.4 on page 51 of NFPA 70E (2000 Edition). Flash Protection Boundary The radiant energy released by an electric arc is capable of maiming or killing a human being at distances of up to ten or even twenty feet. In addition to radiant heat, the molten material and objects ejected by the electrical blast can also be lethal. The flash protection boundary is the closest approach allowed by qualified or unqualified persons without the use of arc protection PPE. For systems under 600 volts ac, 70E sets up two possible ways to calculate the flash boundary. 1. For locations with a total fault exposure of less than 5000 ampere-seconds (fault current in amperes multiplied by clearing time in seconds), a flash boundary of four feet may be used. 2. Above 5000 ampere-seconds, or under engineering supervision for all levels, the following formulas may be used:

Where: = The flash boundary radius DC MVAbf = The bolted fault MVA at the point of exposure MVA = The maximum fault MVA from the transformer feeding the circuit T = The time of exposure (based on protective device operation) Equation 1 provides generally smaller distances because it is based on more pertinent data — e.g. the fault duty at the point of exposure (MVAbf ) as opposed to the transformer fault duty (MVA). For voltage levels in excess of 600 volts, other formulas may be used. The flash boundary is defined as that distance 2 at which the worker is exposed to 1.2 cal/cm for more than 2 0.1 seconds or 1.5 cal/cm for less than 0.1 seconds. In summary for flash boundary: • When an energized conductor is exposed, absolutely no one may approach closer than the flash boundary without wearing appropriate arc protection. • The application of Equation 1 will provide the smaller flash boundaries. • Equation 1 may not be applied without an accurate, upto-date, short-circuit analysis at the point of exposure. • If the flash boundary is smaller than the limited approach boundary, the limited approach boundary is the closest that unqualified persons may approach. Arc Flash Calculations NFPA 70E recognizes that some workers may be required to cross approach boundaries in the day-to-day performance of their job. Voltage measurement, for example, will often require that a worker approach a potentially energized conductor. Empirical Data Calculations As stated previously, significant, new research has been done relative to the amount of energy created by and received from an electrical arc. Doughty, Neal, and Floyd for example have developed empirical formulas for certain electrical arc events. In open air their research shows that the incident energy received from an electrical arc can be calculated by:

13

Arc Flash Safety Handbook — Volume 1

Where: EMA = Maximum open arc incident energy 2 (cal/cm ) DA = Distance from arc electrodes in inches 9 = Arc duration in seconds tA ISC = Bolted fault short-circuit current in kiloamperes

Where: EMB = Maximum arc-in-a-box incident energy 2 (cal/cm ) DB = Distance from arc electrodes in inches 9 tB = Arc duration in seconds ISC = Bolted fault short-circuit current in kiloamperes

Note the following restrictions on Equation 3: 1. Circuit voltage is 600 volts or below (line-to-line voltage). 2. Fault currents (ISC) are greater than 16 kA and less than 50 kA. 3. Distances (DA) must be greater than or equal to 18 inches.

Software Solutions At least two software solutions are available for calculation of incident arc energy. ARCPRO is a commercial software program written in Microsoft Windows. FLUX is a DOS-based, freeware program written by Alan Privette, P.E. FLUX is available for download at several locations on the internet including the Cadick Corporation website at http://www.cadickcorp.com.

It is interesting to note that this empirically developed formula very closely matches the theoretical inverse-square law. Research of this type has shown that the actual arc energy received will be greater if the arc is contained, or focused, by its environment. When Doughty, Neal, and Floyd enclosed their arc in a 20-inch square box with one side open, they found that the arc energy increased as given by:

Selecting Protective Clothing After the incident energy that will be received is calculated, the arc-clothing may be selected by comparing the arc thermal performance value (ATPV) or EBT. The ATPV represents maximum amount of incident energy that a given piece of clothing will attenuate to a “just-curable burn.” This value is determined by the clothing manufacturer using methods described in ASTM standard F 1959. The EBT value is determined using ASTM P S58. This value is used when the ATPV cannot be determined due to fabric break open.

Table 3-3.9.1 Hazard Risk Category Classifications Task (Assumes Equipment Is Energized, and Work Is Done Within the Flash Protection Boundary)

Hazard/Risk Category

V-Rated Gloves

V-rated Tools

Panelboards rated 240 V and below — Notes 1 and 3

__

__

__

CB or fused switch operation with covers off

0

N

N

Circuit breaker (CB) or fused switch operation with covers on Work on energized parts, including voltage testing Remove/install CBs or fused switches

Removal of bolted covers (to expose bare, energized parts)

0 1 1

N

Y Y

N

Y Y

1

N

N

Panelboards or Switchboards rated>240 V and up to 600 V (with molded case or insulated case circuit breakers) — Notes 1 and 3

__

__

__

CB or fused switch operation with covers off

1

N

N

Opening hinged covers (to expose bare, energized parts)

CB or fused switch operation with covers on

Work on energized parts, including voltage testing

0

0

2*

N

N

Y

N

N

Y

600 V Class Motor Control Centers (MCCs) — Notes 2 (except as indicated) and 3

__

__

__

Reading a panel meter while operating a meter switch

0

N

N

Work on energized parts, including voltage testing

2*

CB or fused switch or starter operation with enclosure doors closed CB or fused switch or starter operation with enclosure door open Work on control circuits with energized parts 120 V or below, exposed

0 1

0

N N

Y Y

Figure 5 — NFPA 70E Table 3-3.9.1 (partial reproduction)

N N

Y Y

A simplified approach to PPE selection The 2000 Edition of 70E provides a simpler method for the selection of PPE. Although this technique is arguably overly-conservative, it can provide quick, sufficient solutions for some facilities. Step 1 — Identify the hazard category NFPA Table 3-3.9.1 lists dozens of typical tasks that may be encountered in an industrial/commercial power system. Figure 5 is a partial reproduction of that table. Consider, for example, working on an energized part in a 480 volt switchboard. Such a task is a Hazard/ Risk Category 2*. The * means that in addition to the other clothing or PPE required for a Category 2, the worker must also use a double-layer switching hood and ear protection.

14

Arc Flash Safety Handbook — Volume 1

Table 3-3.9.2 Protective Clothing and Personal Protective Equipment (PPE) Matrix Protective Clothing & Equipment

Protective Systems for Hazard/Risk Category

Hazard/Risk -1 Category (Note 3) Number

Untreated Natural Fiber a. T-shirt (short sleeve) b. Shirt (long-sleeve c. Pants (long)

FR Clothing (Note 1) a. Long-sleeve shirt

__

0

1

2

3

4

__

__

__

__

__

X

X

X

X X X

X

__

__

b. Pants

d. Jacket, parka, or rainwear

FR Protective Equipment a. Flash suit jacket (2-layer)

Changes to Part 3 (Note 4)

X

(Note 6)

X

X

X

__

__

__

__

X

X

X

X

X

c. Coverall

__

__

Step 3 — Refer to NFPA 70E Table 3-3.9.3 to confirm the adequacy of FR Clothing 70E Table 3-3.9.3 is shown here as Figure 7. This table gives the minimum ATPV (or EBT) for the various categories defined in Table 3-3.9.2. A couple of points may help to clarify this table: • The total weight column is typical. A given manufacturer’s clothing may be more or less. • The ATPV that is given is minimum for the particular hazard/risk category.

X

(Note 9)

X

(Note 4)

(Note 6)

(Note 9)

(Note 5)

(Note 5)

(Note 7)

(Note 9)

X

X

AN

AN

AN

AN

__

__

__

__ X

Figure 6 — NFPA 70E Table 3-3.9.2 (partial reproduction)

Under certain conditions the HRC may be reduced by one level. For example, Note 3 (which applies to our previously selected example) tells us that if the available fault current is less than 10,000 amperes, the HRC may be reduced by one level. Thus, instead of an HRC 2*, we would select an HRC 1*. Step 2 — Select the PPE from the PPE matrix Figure 6 is a partial reproduction of 70E 2000 Table 33.9.2. This table allows the user to select the type of PPE required for the task at hand. For our example, the worker is required to wear an untreated, natural-fiber tee-shirt as well as untreated, natural fiber long pants. (Note 6 allows the elimination of the long pants provided the FR clothing has an ATPV of at least 8.) The worker must also wear a long-sleeve FR shirt and pants. Note 7 allows the worker to substitute an FR coverall for these requirements. Please note that this example is intended to illustrate the method, not serve as a short-cut for going through all of the necessary calculations.

Very little has been changed since the 1995 version. Essentially, the only changes were those required by changes to other parts. For example, the substantial increase in the hazardous location section (Part 1 Chapter 5) required that some changes be made in Part 3 to reference properly. Other than the various NETA standards, NFPA 70B continues to be the sole regulatory source of information for maintenance related activities.

Changes to Part 4 The 2000 edition is the first time that anything has appeared in Part 4. In other words — everything in Part 4 is new to this edition. Procedures, equipment, and training requirements are laid out for four different types of special equipment including: • Electrolytic cell lines • Batteries and battery rooms • Lasers • Power electronic equipment. This entire section should be used as a ready reference for these special types of equipment.

Conclusion NFPA 70E is and will continue to be the most up-todate and ready reference for regulatory information covering electrical safety programs. For additional information, the reader is directed to two different industry texts on electrical safety: The Electrical Safety Handbook by John Cadick (McGrawnd Hill, currently in 2 edition) Electrical Safety in the Workplace by Ray Jones, P.E. and Jane Jones (NFPA)

15

Arc Flash Safety Handbook — Volume 1 Table 3-3.9.3 Protective Clothing Characteristics Typical Protective Clothing Systems

Hazard Risk Category

Clothing Description (Number of clothing layers is given in parentheses)

Total Weight 2 oz/yd

Minimum Arc Thermal Performance Exposure Value (ATPV)* or Breakopen Threshold Energy (EBT)* Rating of PPE cal/cm2

0

Untreated cotton (1)

4.5 - 7

N/A

1

FR shirt and FR pants (1)

4.5 - 8

5

2

Cotton underwear plus FR shirt and FR pants (2)

9 - 12

8

3

Cotton underwear plus FR shirt and FR pants plus FR coverall (3)

16 - 20

25

4

Cotton underwear plus FR shirt and FR pants plus double layer switching coat and pants (4)

24 - 30

40

*ATPV is defined in the ASTM P S58 standard arc test method for flame resistant (FR) fabrics as the incident energy that would just cause the onset of a second degree burn (1.2 cal/cm2). EBT is reported according to ASTM P S58 and is defined as the highest incident energy which did not cause FR fabric breakopen and did not exceed the second-degree burn criteria. EBT is reported when ATPV cannot be measured due to FR fabric breakopen.

Figure 7 — NFPA 70E Table 3-3.9.3

Other references: “Predicting Incident Energy to Better Manage the Electric Arc Hazard on 600 V Power Distribution Systems,” IEEE paper by Richard L Doughty, Thomas E. Neal, and H. Landis Floyd. Please note that tables are not reproduced in their entirety. Refer to NFPA 70E for full details. A registered professional engineer and the founder and president of the Cadick Corporation, John Cadick has specialized for over three decades in electrical engineering, training, and management. His consulting firm, based in Garland, Texas, specializes in electrical engineering and training and works extensively in the areas of power system design and engineering studies, condition-based maintenance programs, and electrical safety. Prior to creating the Cadick Corporation and its predecessor Cadick Professional Services, he held a number of technical and managerial positions with electric utilities, electrical testing companies, and consulting firms. In addition to his consultation work in the electrical power industry Mr. Cadick is the author of Cables and Wiring, The Electrical Safety Handbook, and of numerous professional articles and technical papers.

16

Arc Flash Safety Handbook — Volume 1

Protective Devices Maintenance as it Applies to the Arc/Flash Hazard NETA World, Summer 2002 Issue by Dennis K. Neitzel, C.P.E. AVO International Training Institute

One of the key components of the flash hazard analysis which is required by NFPA 70E-2000, Part II, paragraph 21.3.3 is the clearing time of the protective devices, primarily circuit breakers and protective relays. Fuses, although they are protective devices, do not have operating mechanisms that would require periodic maintenance; therefore, this article will not address them. The primary focus of this article will be the maintenance issues for circuit breakers and protective relays. Molded-case and low-voltage, power circuit breakers (600 volts or less) will generally clear a fault condition in three to eight cycles. To be conservative a clearing time of eight cycles should be used. The majority of older mediumvoltage circuit breakers (2300 volts or greater) will clear a fault in around eight cycles with the newer ones clearing in three to five cycles. Protective relays will generally add approximately three to four cycles to the clearing time of the medium-voltage circuit breaker. Where correct maintenance and testing are not performed, extended clearing times could occur, creating an unintentional time delay that will affect the results of flash hazard analysis. All maintenance and testing of the electrical protective devices addressed in this article must be accomplished in accordance with the manufacturer’s instructions. The NETA Maintenance Testing Specifications for Electrical Power Distribution Equipment and Systems is an excellent source of information for performing the required maintenance and testing of these devices. Visit the NETA website for more information at http://www.netaworld.org. This article will address some of the issues concerning the correct maintenance and testing of these protective devices. It will also address how protective device maintenance relates to the electrical arc/flash hazard.

Molded-Case Circuit Breakers Generally, maintenance on molded-case circuit breakers is limited to the correct mechanical mounting, electrical connections, and periodic manual operation. Most lighting, appliance, and power panel circuit breakers have riveted frames and are not designed to be opened for internal inspection or maintenance. All other molded-case circuit breakers that are UL approved are factory-sealed to prevent access to the calibrated elements. An unbroken seal indicates that the mechanism has not been tampered with and that it should function as specified by UL. A broken seal voids the UL listing and the manufacturers’ warranty of the device. In this case, the integrity of the device would be questionable. The only exception to this would be a seal being broken by a manufacturer’s authorized facility. Circuit breakers installed in a system are often forgotten. Even though the breakers have been sitting in place supplying power to a circuit for years, there are several things that can go wrong. The circuit breaker can fail to open due to a burned out trip coil or because the mechanism is frozen due to dirt, dried lubricant, or corrosion. The overcurrent device can fail due to inactivity or a burned out electronic component. Many problems can occur when maintenance is not performed and the breaker fails to open under fault conditions. This combination of events can result in fires, damage to equipment, or injuries to personnel.

Low-Voltage, Power Circuit Breakers Low-voltage, power circuit breakers are manufactured under a high degree of quality control, of the best materials available, and with a high degree of tooling for operational accuracy. Manufacturer’s tests show these circuit breakers to have durability beyond the minimum requirements of standards. All of these factors give these circuit breakers a very high reliability rating. However, because of the varying application conditions and the dependence placed upon

17

Arc Flash Safety Handbook — Volume 1 them for protection of electrical systems and equipment as well as the assurance of service continuity, inspections and maintenance checks must be made on a regular basis. Several studies, including those by IEEE, have shown that lowvoltage power circuit breakers which were not maintained within a five-year period, have a 50 percent failure rate. Maintenance of these breakers will generally consist of keeping them clean and appropriately lubricated. The frequency of maintenance will depend to some extent on the cleanliness of the surrounding area. If much dust, lint, moisture, or other foreign matter were present then, obviously, more frequent maintenance would be required.

************************************************************* This program is made available to the general public for the purpose of calculating heat flux received at a surface some distance from an electric arc. The use of this program is the responsibility of the user. The author makes no warranty to the accuracy of the results and accepts no responsibility any damage that may arise from its use.

*************************************************************

Most of the inspection and maintenance requirements for low-voltage, power circuit breakers also apply to mediumvoltage, power circuit breakers. Manufacturers recommend that these breakers be removed from service and inspected at least once per year. They also state that the number and severity of interruptions may indicate the need for more frequent maintenance checks. Always follow the manufacturer’s instructions because every breaker is different.

Enter the arc current(amps) ? 20000 Enter the arc gap(inches) ? 3 Enter the supply voltage(volts) ? 480 Arc column area 43.03264 sq. inches Arc column cir. 14.34421 inches Arc diameter 4.565908 inches Arc power in watts - 1781250 Arc power in calories/sec - 425540.6 Heat flux on surface of arc 1533.146 cal/cm^2-sec Enter the distance from the arc to the receiving surface ? 18 Transfer Shape Factor 1.482744E-02 Heat Flux at Receiving Surface 22.73263 cal/cm^2-sec Enter the number of cycles for the arc duration ? 5 Arc Duration 8.333001E-02 seconds Total Calories per Sq. Cm. at Receiving Surface 1.89431

Protective Relays

Do You Wish To Run Another Case? (Y or N) ?

Medium-Voltage, Power Circuit Breakers

Relays must continuously monitor complex power circuit conditions, such as current and voltage magnitudes, phase angle relationships, direction of power flow, and frequency. When an intolerable circuit condition, such as a short circuit (or fault) is detected, the relay responds and closes its contacts and the abnormal portion of the circuit is deenergized via the circuit breaker. The ultimate goal of protective relaying is to disconnect a faulty system element as quickly as possible. Sensitivity and selectivity are essential to ensure that the right circuit breakers are tripped at the right speed to clear the fault, minimize damage to equipment, and to reduce the hazards to personnel.

Flash Hazard Analysis As noted at the beginning of this article, NFPA 70E2000 requires a flash hazard analysis be performed before anyone approaches exposed electrical conductors or circuit parts that have not been placed in an electrically safe work condition. In addition, Paragraph 2-1.3.3.2 requires a flash protection boundary to be established. All calculations for determining the incident energy of an arc and for establishing a flash protection boundary require the arc clearing time. This clearing time is derived from the engineering coordination study which is based on what the protective devices are supposed to do. Maintenance is a critical part of the flash hazard issue. Evidence has proven that inadequate maintenance can cause unintentional time delays in the clearing of a short-circuit condition. If, for example, a low-voltage, power circuit breaker had not been operated or maintained for several years and the lubrication had become sticky or hardened, the

Calculation with a Five-Cycle Clearing Time

circuit breaker could take several additional cycles, seconds, minutes, or longer to clear a fault condition. The following is a specific example. If a flash hazard analysis is performed based on what the system is suppose to do, let’s say five-cycle clearing time, and there is an unintentional time delay, due to a binding mechanism, and the breaker clears in 30 cycles, the worker could be seriously injured or killed because he/she was underprotected. If the calculation is performed for a 20,000 ampere fault, 480 volts, three-inch arc gap, the worker is 18 inches from the arc, with a five-cycle clearing time for a three-phase arc in a box (enclosure), the results would be approximately 6.5 2 cal/cm which would require an arc/flash Category 2 protection based on NFPA 70E-2000, Part II, Table 3-3.9.3. Figure 1 uses the heat flux calculator (developed by Alan Privette) and the values above for a five-cycle clearing time. 2 This value of 1.89431 cal/cm is based on a single-phase arc in open-air. As a general rule of thumb, the value of 1.89431 would be multiplied by a factor of two for a single-phase arc 2 in a box (2 x 1.89431 = 3.78862 cal/cm – Category 1) and by a factor of 3.4 for a multiphase (three-phase) arc in a box 2 (3.4 x 1.89431 = 6.440654 cal/cm – Category 2). If the clearing time is increased to 30 cycles (Figure 2) 2 then the results are approximately 38.7 cal/cm , which requires an arc/flash Category 4 protection. The value of 2 11.36586 cal/cm is based on a single-phase arc in open-air. Again, as a general rule of thumb, the value of 11.36586

18

Arc Flash Safety Handbook — Volume 1

************************************************************* This program is made available to the general public for the purpose of calculating heat flux received at a surface some distance from an electric arc. The use of this program is the responsibility of the user. The author makes no warranty to the accuracy of the results and accepts no responsibility any damage that may arise from its use.

************************************************************* Enter the arc current(amps) ? 20000 Enter the arc gap(inches) ? 3 Enter the supply voltage(volts) ? 480 Arc column area 43.03264 sq. inches Arc column cir. 14.34421 inches Arc diameter 4.565908 inches Arc power in watts - 1781250 Arc power in calories/sec - 425540.6 Heat flux on surface of arc 1533.146 cal/cm^2-sec Enter the distance from the arc to the receiving surface ? 18 Transfer Shape Factor 1.482744E-02 Heat Flux at Receiving Surface 22.73263 cal/cm^2-sec Enter the number of cycles for the arc duration ? 30 Arc Duration .49998 seconds Total Calories per Sq. Cm. at Receiving Surface 11.36586 Do You Wish To Run Another Case? (Y or N) ? Calculation with a Thirty-Cycle Clearing Time

would be multiplied by a factor of two for a single-phase arc 2 in a box (2 x 11.36586 = 22.73172 cal/cm – Category 3) and by a factor of 3.4 for a multiphase (three-phase) arc in 2 a box (3.4 x 1.89431 = 38.643924 cal/cm – Category 4). Therefore, as can be seen, maintenance is extremely important to an electrical safety program. Maintenance must be performed according to the manufacturer’s instructions in order to minimize the risk of having an unintentional time delay in the operation of the circuit protective devices.

Summary With the appropriate mixture of common sense, training, manufacturers’ literature, and spare parts, correct maintenance can be performed and power systems kept in a safe, reliable condition. Circuit breakers, if installed within their ratings and correctly maintained, should operate troublefree for many years. However, if operated outside of their ratings or without maintenance, catastrophic failure of the power system, circuit breaker, or switchgear can occur causing not only the destruction of the equipment but serious injury or even death of employees working in the area. Dennis K. Neitzel, C.P.E., Director of AVO Training Institute, Dallas, Texas, earned his bachelor’s degree in electrical engineering management and his master’s in electrical engineering applied sciences from Columbia Pacific University. He earned his Certified Plant Engineer (C.P.E.) through the AFE and his Certified Electrical Inspector-General through

the IAEI. He has been a Principle Committee Member for the NFPA 70E, Standard for Electrical Safety Requirements for Employee Workplaces since 1992 and is co-author of the Electrical Safety Handbook, Second Edition, McGraw-Hill Publishers. He is a member of the Institute of Electrical and Electronics Engineers, the American Society of Safety Engineers, the Association for Facilities Engineering, the International Association of Electrical Inspectors, and the National Fire Protection Association.

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Arc Flash Safety Handbook — Volume 1

Electric Arc Flash Protective Clothing NETA World, Summer 2004 Issue by Paul Hartman Sigma Six Solutions

Introduction

Definitions

Advances in technology have definitely improved the arc flash clothing options available to workers. It was not all that long ago – the 1980s – that the choice of flash protection was extremely limited, and few employers even had a policy on flash clothing. Today there are a dozen or so brand names of arc flash protection clothing, with some brands providing different fabrics ranging from five to 13 ounces per square yard fabric weight. These fabrics are available in an array of colors, weaves, and textures, as can be seen in Figure 1. As with all safety equipment, arc flash clothing is of no use to anyone unless it is being used at the time of an arc flash. This article addresses available fabrics to be worn by workers and the associated definitions of arc flash terms.

Arc Thermal Performance Value (ATPV): This value is presented in calories per square centimeter and represents the maximum capability for arc flash protection of a particular garment. This rating also applies to fabrics. However, a garment made from more that one layer of arc flash rated fabric will have a calories per square centimeter rating greater than the sum of the ATPV ratings of the original fabrics. The calories per square centimeter rating of most arc flash protective suits, coveralls, and coats is commonly sewn into the fabric in large letters on the outside of the garment. Flame Resistant (FR): “Flame resistant” can describe a fabric naturally resistant to burning but also can represent a material with special treatment applied to the fabric. Occasionally, the letters FR are used to represent “flame retardant.” This can lead to some confusion because a flameretardant treated fabric is flame resistant, but a flame-resistant fabric is not necessarily flame retardant. Flame Retardant: This term could be used to describe a fabric made up of a flammable fabric treated in such a way that it will provide arc flash protection. Fabric Weight: This is usually represented in one of two ways: ounces per square yard or grams per square meter. Both of these values essentially refer to the thickness of the fabric. The more ounces per square yard, the more material exists in the same square yard of fabric. Heat Attenuation Factor (HAF): This is the amount of heat blocked by the fabric. Even though a fabric may be 100 percent flame resistant, that does not mean it will block all of the heat to which it is exposed. An HAF of 85 percent means that it will block 85 percent of the heat the fabric encounters. This applies to a short burst of arc flash heat – typically less than one second. In the event of prolonged heat exposure, the HAF would be much lower.

Figure 1

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Arc Flash Safety Handbook — Volume 1

Calories per Centimeter Squared: This is a number identifying the amount of energy that can be delivered to a point at a particular distance from an arc flash. Once this value is known, the ATPV rating of the flash clothing required for work at that distance from the potential flash hazard is also known. Energy Break-Open Threshold (EBT): Primarily, this addresses the physical strength of the fabric with respect to thermal energy and at what arc flash value the fabric will fail. Personal Protective Equipment (PPE): This term is primarily used to describe all safety equipment used by personnel to protect personnel. This includes fall protection, confined space, electrical hazards, and so on. Hazard Risk Category (HRC): This is a 2004 NFPA 70E rating of exposure levels for particular types of equipment. The values range from zero to four, with a zero HRC not requiring any ATPV-rated PPE. The minimum ATPV rating for Categories One through Four are as follows: Category One: five calories per square centimeter • Category Two: eight calories per square centimeter • Category Three: 25 calories per square centimeter • Category Four: 40 calories per square centimeter •

Overclothing: Any arc flash rated clothing with a HAF of less that 70 percent is considered overclothing. This means that the flash-rated clothing must be worn over a suitable undergarment to protect the wearer. Typically, the undergarments in this situation would be 100 percent cotton. Other undergarment fabrics may be required in special situations.

Arc Flash Clothing Labels In the past there were no real guidelines as to what the manufacturers of arc flash clothing were required to place on the label. New ASTM standards mandate a minimum outline of that which must be clearly printed on the label of arc flash rated clothing. Some manufacturers have made sure that workers know their product is not intended for arc flash protection, as can be seen in Figure 2. The list for ASTM flash clothing label requirements is as follows: 1. Manufacturer 2. Care instructions 3. Fabric fiber content 4. Garment size 5. Manufacturer tracking code 6. Meets F1506 Fire Retardant Standards 7. ATPV rating in calories per square centimeter For some unknown reason, the HAF was not included on the label-requirement list. Some manufacturers include this value on the label anyway. The HAF should be evaluated when considering what types of arc flash PPE to purchase. This information, if not on the label, is readily available from the manufacturers. Figure 3 shows a hard hat liner that had been in use for years. The label states that the outer shell of this liner is “Flame Retardant, until Washed or Dry Cleaned.” This garment was manufactured more than 15 years ago and met the standards of the day. The only issue here is that when a person looks at the label the first thing they see is “FLAME RETARDANT.” The fact that the inner part of the liner has no fire resistant characteristics is not clearly identified, and the smallest print on the tag identifies that the first time you wash this item it removes all flame protection.

Fabrics for Electric Arc Flash Protection

Figure 2

100 Percent Cotton: It was not all that long ago that plain old cotton was considered the appropriate protective clothing when an electrical arc exposure was present. The thinking was that cotton provided much better protection than polyester, nylon, acetate, and the like. This is true. However, along came products that soon made untreated cotton an undesirable fabric for these situations. Flame-Retardant Treated 100 Percent Cotton: One such fabric available today is marketed under the trade name “Indura.” This fabric is made by Westex and is guaranteed to maintain flame retardant performance throughout the life of the garment. This fabric has an expected wear life of 50 to 75 home launderings. This means that five sets of shirts and pants, each worn once per week, will last 12 to16 months in the range of light- to severe-use conditions. In Indura-engineered fabrics, the flame retardant chemical impregnated on the cotton fiber core acts as a catalyst promoting the charring of the fabric. This accelerated char-

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Arc Flash Safety Handbook — Volume 1

93 Percent Nomex, Five Percent Kevlar, and Two Percent Antistatic Fiber: This long-winded description is most commonly know by its trade name “Nomex IIIA.”This is the latest and greatest of the Nomex line that has been manufactured by DuPont. Nomex IIIA is a lightweight, inherently flame-resistant fiber blend. It does tend to have a higher heat let-through rate and is not recommended for use around molten metals. This fabric is available in weaves from 3.3 to 7.5 ounces per square yard. Some weights are available in ripstop and twill weaves. Nomex IIIA has an expected wear life of 30 to 48 months. 60 Percent Kevlar, 40 Percent Polybenzimidizole: This blended fabric is marketed under the trade name of “PBI/ Kevlar.” The polybenzimidizole fiber is manufactured by Celanese Acetate; the Kevlar fiber is made by DuPont. Figure 3

ring prohibits the support of combustion by reducing the fuel source. The flame retardant chemical acts in the solid phase to produce this char. The mechanism of action is not based on a gaseous process of extinguishing or “snuffing out” the flame. It is very important that flame resistant fabrics be maintained in a clean condition to realize their full protection potential. Flame-Retardant Treated 88 Percent Cotton, 12 Percent Nylon: Previously, it was stated that nylon was an undesirable fabric for electric arc blast protection. With this blend there is a mechanical type reaction when it is exposed to excessive heat. The nylon melts and essentially fills up the gaps between the cotton fibers creating a more solid defense against the heat source. This fabric is sold under the trade names of “Banwear” (made by Itex) and “Indura UltraSoft” (made by Westex). Both of these products guarantee that the flame retardant performance of the fabric is maintained throughout the life of the garment. One can expect Banwear and Indura UltraSoft to last 18 to 30 months when worn daily and home laundered once per week. 45 Percent Combed Cotton Fiber, 55 Percent Modacrylic: Modacrylic is a shortened name for “fibrous flame-retardant fiber.” By combining these two fibers the fabric “Firewear” is produced. Firewear is manufactured by Springfield LLC. These woven fabrics range in weight from 5.5 to 9.5 ounces per square yard and are available in both twill and plain weaves. Firewear also is available in knits from 6.0 to 14.0 ounces per square yard. Before the fibrous flame-retardant fibers are exposed to heat and flames, they look and feel just like any other textile fiber. Upon exposure to flames, a reaction begins: certain molecular components of the fiber emit non-combustible gas that is released through tiny pores in the fiber. This smothers the fire in much the same way that a fire extinguisher does. These gases shut off the oxygen feeding the flames, thereby preventing further burning. Firewear has an expected wear life of 18 to 30 months when worn daily and home laundered once per week.

Care and Cleaning A variety of flame-resistant fabrics are available in today’s marketplace. Each fabric has unique wear, comfort, appearance, and durability characteristics. Each of these issues should be considered when making a flame-resistant garment purchase. Industrial laundering creates more wear on a garment than home laundering. Also, it has been found that heavy facial growth has a negative effect on wear life of a collared shirt. Additionally, repeated abrasion of any type shortens wear life in the area on the garment where the abrasion occurs. Indura should not be laundered with hypochlorite (chlorine) bleach because repeated exposure will break down the finish and is destructive to the fabric and the color. Most flame-resistant fabrics, including Nomex, bear instructions prohibiting the use of chlorine bleach because it is destructive to the fabric strength and color even if flame resistance is not affected.

Paul Hartman has over 18 years experience in start-up, commissioning, maintenance, and training in power generation, including international projects in Pakistan, Indonesia, Thailand, Brazil, and Korea. He has been an instructor for state certified continuing education programs. Paul is currently Vice President of Sigma Six Solutions. He is a regular contributor to NETA World and a frequent speaker at NETA’s Annual Technical Conference.

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Arc Flash Safety Handbook — Volume 1

Corrective Measures to Arc Flash Problems — Is It that Simple? NETA World, Fall 2004 Issue by Ron Widup Shermco Industries

Introduction With all the talk about the NFPA 70E, Hazard Risk Analysis, IEEE 1584, and all of the associated elements related to arc flash hazards, what do you do when you discover an arc flash hazard within your facility? Hint: Run like the wind….. While at times it can be a very complicated (read: expensive) solution to solving your problem, more often than not it is, or can be, a simple solution. The following case studies are examples of how some arc flash hazards can be corrected without too much effort, and heck, you might even impress your boss (doubtful).

Background One of the first, and most basic, principles of an electrical safety program is to identify and minimize hazards in an electrical system. One of the key elements to identifying these hazards is to quantify the electrical arc energy in the system, both magnitude and distance. An arc flash engineering study will get you these values, but it won’t buy you a new pair of shoes. If a worker is to work on or near exposed conductors that will not be in an electrically safe work condition,* a shock hazard analysis and flash hazard analysis are required. *Electrically Safe Work Condition; Per NFPA 70E, Standard for Electrical Safety in the Workplace, 2004 Edition: A state in which the conductor or circuit part to be worked on or near has been disconnected from energized parts, locked/tagged in accordance with established standards, tested to ensure the absence of voltage, and grounded if determined necessary.

While personal protective equipment (PPE) manufac2 turers make flash suits with arc ratings up to 100 cal/cm , NFPA 70E does not have a Hazard Risk Category for 2 incident energies above 40 cal/cm . Working on energized 2 circuits with energy levels in excess of 40 cal/cm should be avoided by all means necessary. If energized work must be performed on these circuits, steps should be taken to reduce the hazard before the work is to be performed. Although it would seem as though a 100 calorie Hazard Risk Category level might be one you could easily classify as the BOD, or “Big ‘Ol Dufus” category. So if you have determined that a hazard exists, and have performed an arc flash study, you are on your way to protecting your workers from the hazards. But now that you know the hazards exist along with the quantifiable data, what’s next? Happy Hour! OK, I digress — a few examples with solutions are outlined below.

Case Study Examples Case Study No. 1 2000 kVA Transformer With No Main Breaker Invariably, just about any 1500 — 3000 kVA 480-volt unit substation transformer will have a high incident energy level between the transformer secondary bushings and the main breaker line side bus. In this example, a 480-volt outdoor substation is fed from a 2000 kVA transformer. The transformer primary is protected with a 15 kV vacuum circuit breaker. The substation does not have a main breaker, only feeder breakers. For a diagram of this design, read “Engineering 101 — What NOT to do.” After analysis, it was determined that the incident energy 2 on the main bus was approximately 109 cal/cm . At this level of incident energy and because the feeder breakers were not protected by a main breaker, none of the feeder breakers

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Arc Flash Safety Handbook — Volume 1 could be racked in or out without being in violation of the requirements as established in NFPA 70E. And, one of the most prevalent comments from the owner of the equipment was, “Why, after 25 years, do you now tell me I cannot operate those same breakers that I have been operating (racking in and out) for the last 25 years?” The answer is, obviously, “Because.” OK, that may not be exactly the right answer, but because we now know what the incident energies are, and because we now know we have to do something about it, and because we care about our employees (well, maybe the first shift employees) — it is because of these items that we need to fix it. So what’s the solution? The owner can’t change his substation out without going through a time intensive capital spending request with corporate, and he can’t just all-of-a-sudden stop racking breakers in and out. So, what is he to do? Call the Coordination Police, Batman! This particular transformer was coordinated with the system to maintain maximum uptime without damaging the transformer, with a relay time-dial setting of 5.0. After analyzing the data, it was determined that a time-dial setting of 2.0 will still maintain system stability, allow for proper coordination, and will reduce the incident energy on the low-voltage bus 2 2 from 109 cal/cm to about 40 cal/cm . Viola! We are now down to a level at which we can get burned just enough to live and tell about it! Mission accomplished.

Case Study No. 2 Racking In (or Out) A Main Breaker on a 2500 kVA Unit Substation In this example, take the same situation as above, only now insert a main breaker on the 480-volt bus in a doubleended substation. You have now solved one of the two problems. The solution to one of the problems is that now you have put an overcurrent device between the transformer secondary and the feeder breaker main bus (with the main breaker). Problem number two, the incident energy on the line side of the main breaker to the transformer secondary bushings is still high. So now what? Call the Coordination Police Batman! What?! Phone’s busy? Then call the electrical department! So what can the electrical department do for you? Let’s take a look at the situation:

• You have a 13.8 kV fused switch in front of a 2500 kVA

transformer

• The transformer feeds a main breaker on one side of the

substation

• The main breaker must be closed to get power to the

substation

• The double-ended substation is configured for open-

transition operation

Got it? Now think about the operation of the substation — is there any reason to have the transformer energized before racking the breaker in or out? (insert Jeopardy theme here) No? Well good, because you have just changed one

Diagram 1

simple plant procedure and reduced your exposure to the hazard. Because after all, if there is no electricity, there is no hazard, right? Almost…. It is not exactly “electrically safe,” but it is in a much safer condition than if you had it energized, yes? As you can see from Diagram 1, at a distance of 36 inches the incident energy at the 13.8 kV switch primary 2 is 4.5 cal/cm , and on the load side of the switch it is 0.2 2 cal/cm ! Now jump to the 480-volt side of the transformer, 2 line side of the main breaker, and it becomes 76.4 cal/cm at 24 inches — again a situation that you do not want any part of, unless you like to tan very quickly. The lesson for Case No. 2? Turn it off, Einstein.

Case Study No. 3 The Case of the Slow Fuse — or How I Spent my Summer Vacation In this example, check out Diagram 2, where there is a 10,000 kVA transformer fed from a 13.8 kV fused switch, which then feeds a medium-voltage main breaker, and ultimately feeds a medium-voltage motor control center

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Arc Flash Safety Handbook — Volume 1

Diagram 2

Diagram 3

(Emcee, See?) The MCC feeds another fused switch, which then feeds a 1000 kVA transformer, reactor, and variable frequency drive (VF D-Big Money) for a 900 hp motor. Simple, right?

With all of those overcurrent devices, including switches, breakers, fuses, reactors, and lengths of cable you would think the power system would owe you a few incident energies. Sorry, it is not to be. Initially there was a s-l-o-w speed fuse in the 4.16 kV main switch for the VFD. How did we know it was slow fuse? It had a degree from Texas A&M (bad Texas joke).

Arc Flash Safety Handbook — Volume 1 Actually, when the application was changed to a standard speed fuse, it was apparent that there was no room in Bryan-College Station for no slow-speed fuse. Check out the incident energies before and after the fuses were changed: Slow Fuse (Diagram 2) Reactor Line Side 51.9 cal/cm2 Reactor Load Side 52.7 cal/cm2

Standard Fuse (Diagram 3) Reactor Line Side 24.7 cal/cm2 Reactor Load Side 25.3 cal/cm2

As Top Gun Maverick says “I feel the need, the need for speed.” Another interesting point of discovery, the incident energy is higher on the load side of the reactor than it is right. I thought reactors were supposed to limit current, thereby limit the amount of incident energy. Not on my watch, soldier! While these case studies are but a few of the thousands of it shows that the issues don’t necessarily always involve from the hazards of the electric arc may just be a simple one. Which, after all, is what it is all about…. Be Safe!

References: 1. NFPA 70E, Standard for Electrical Safety in the Workplace. Quincy, MA: National Fire Protection Association, 2004 2. Safety Basics, Handbook for Electrical Safety. St. Louis, MO: Cooper Bussman, Inc., Edition 2 Ron A. Widup, Executive Vice President/General Manager of Shermco Industries has over 20 years of experience in the low-, medium-, and high-voltage switchgear and substation market. He is a principal member of NFPA technical committee 70E (Standard for Electrical Safety in the Workplace) and a member of NEC Code Panel 11. He is past president of NETA and currently a member of the Board Level IV Senior Test Technician.

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Arc Flash Safety Handbook — Volume 1

Electrical Safety — Myths and Rumors NETA World, Fall 2004 Issue by David K. Kreger Electrical Reliability Services

In my travels throughout these last years I have had opportunity to present electrical safety as well as other types of technical training. I continue to be flabbergasted at some of the comments I hear from students or other supposedly “qualified” electrical workers regarding the requirements to maintain a safe work environment. Some examples of these questions and statements are given below, followed by appropriate answers.

work procedures to mitigate these hazards. I will add that, even though the appropriate tools and PPE are available, the supposedly qualified worker may not know what to do with them. For example, I witnessed a 20-year veteran pull the insulating rubber gloves on over the leather gauntlets! When questioned, he responded, “I always wears them like that since the rubber part is the shock protection part and the leather inside keeps my hands from getting sticky.”

1. OSHA has a new requirement to perform a hazard or risk analysis before beginning each job. This statement refers to CFR 29, 1910.132(d)(1), which says: “The employer shall assess the workplace to determine if hazards are present, or are likely to be present, which necessitate the use of personal protective equipment (PPE). If such hazards are present, or likely to be present, the employer shall: 1910.132(d)(1)(i) Select, and have each affected employee use, the types of PPE that will protect the affected employee from the hazards identified in the hazard assessment.” This new requirement is not new at all. Since OSHA’s inception in the early 1970s, the entire premise has been to ensure, as much as possible, a safe work environment for employees. Each employer has an obligation to determine what hazards an employee may face on the job. Once the hazard has been identified, the employer has further obligation to provide the appropriate training, PPE, or other work procedures that would allow the employee to perform the task safely. Specific to the electrical industry are several hazards of which qualified workers should be aware in order to be considered “qualified.” Shock and arc flash burns are the two primary hazards faced when working on or around energized electrical equipment. Therefore, the employer has an obligation to identify possible shock hazards, identify possible flash burn hazards, and provide the appropriate tools, PPE, or

2. Insulated gloves should never be worn when using insulated live-line tools. If the insulation on the tool is bad the worker would never know it while wearing insulated gloves. This statement also was posed by a 20-year veteran. I had to think about that a moment. Hmm, would I want to find out the tool is bad by not wearing gloves? Those of you that have ever watched insulation break down when performing high-potential testing will testify that the breakdown happens quickly — faster than you could drop a bad switch stick! 3. We would like to adopt NFPA 70E as our working electrical safety policy, but it is entirely too cumbersome. I have advocated NFPA 70E in its forms throughout the years and do admit in some cases the recommendations may be a bit cumbersome. However, realizing the intent of the publication should shed light on how to implement the appropriate policies. There is not, to my knowledge, a single safety document covering every possible scenario in the electrical industry, nor will there ever be since ours is such a dynamic field. In the absence of specific rules from OSHA, the intent should still be to protect the workforce from hazards. Therefore, a site-specific or activity-specific policy would be appropriate, as long as it meets the intent of protecting the workforce.

Arc Flash Safety Handbook — Volume 1 I keep a keen eye on the citations and violations of federal and many state OSHA organizations and have yet to see a citation for not following an NFPA 70E recommendation verbatim. NFPA 70E is not an enforceable document — yet. It is a guideline for developing a safe electrical work environment and has many practical applications the employer could use or modify, if necessary, to meet specific needs. If an employer were to adopt NFPA 70E in its entirety, I am certain it would be following all the OSHA rules. 4. If I were actually to develop a hazard analysis and energized electrical work permit before performing every task, as recommended in NFPA 70E, I would spend all day doing hazard analysis and never get the work done. If you weren’t already doing some form of hazard analysis before performing electrical work, I would say you should find a different occupation! The recommendation to perform a hazard analysis and develop a written energized electrical work permit plan for hazard mitigation applies to those tasks that are not routine in nature (“not routine” being less frequently than annually). The system will not be locked and tagged, and the system will be energized or possibly energized. If the task is performed frequently, an original hazard analysis with successful mitigation techniques should already be in place in one form or another. Thus, another analysis is not required. Further, NFPA 70E, 2004, Article 130.1(A)(3) Exemptions to Work Permit says: “Work performed on or near live parts by qualified persons related to tasks such as testing, troubleshooting, voltage measuring, etc., shall be permitted to be performed without an energized work permit, provided appropriate safe work practices and personal protective equipment in accordance with Chapter 1 are provided and used.” To give an example, a qualified worker should already know the hazards involved in taking current measurements in a motor control center. Would the hazards change from one bucket to another? I would say no. Therefore, the same techniques found to be successful in one application of shock and flash protection would be successful in other similar applications. There is no reason to perform multiple (written) hazard analyses and mitigation procedures for basically the same task. 5. OSHA has a new requirement to perform an arc flash hazard assessment and mark the equipment. No, and no. OSHA has no new mandate to perform a specific hazard assessment for arc flash. There is an existing requirement to perform a hazard analysis for any hazard an employee may face on the job (see 1910.132(d)(1) in #1 above). That requirement has been in the register for years. What is new is the ability to quantify the existing arc flash hazard. Now that reasonable engineering means are available to quantify the flash hazard, there is more emphasis on ensuring the employees are protected. In the 2002 National Electric Code (NEC) Article 110.16 requires the marking

27 of flash hazards on equipment wherever the possibility of energized work exists. This is not an OSHA mandate, it is an NEC requirement. 6. I didn’t have to be sitting down to hear the news that there is an arc flash hazard in electrical equipment. I already knew that, so why do we have to put a sign on the equipment? This issue has been a hot topic in the field. I again refer to the intent of the code, not necessarily the verbatim application. In the fine print note associated with NEC Article 110.16, it says to refer to NFPA 70E for assistance and then mentions key terms: “determining the severity of the hazard,” “qualified worker,” “appropriate PPE.” I sincerely believe the intent of Article 110.16 is to arm the qualified worker with enough information to make an intelligent choice when selecting the appropriate PPE: CFR 29 also says, in 1910.335(a)(1)(i), that “Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body to be protected and for the work to be performed.” One of the requirements to be considered qualified to perform electrical work is the ability to identify live versus other components in electrical equipment and to identify operating system voltages. 7. If there were a sign on a piece of equipment that said, “DANGER — VOLTAGE,” would that be sufficient information for a qualified worker to select the appropriate insulated gloves or tools? I think not. The voltage level is what quantifies the hazard so the appropriate PPE and tools can be selected. The intent of the arc flash protection program should be the same. Simply putting a sign on a piece of equipment that says, “DANGER — FLASH HAZARD” would not be sufficient information for a qualified worker to select the appropriate fire-retardant materials or flash protection equipment. The purpose of the training requirement to identify system voltages and live versus other components is twofold: ability to determine when a shock hazard exists and ability to determine level of insulating tools or gloves required. There should also be a training requirement associated with arc flash protection. Never have I seen so many blank stares from supposedly qualified electrical workers as when I show an example of an arc flash warning sign indicating magnitude of hazard at a working distance. 8. That sign says there are 11.4 calories at 18 inches. I ate ten times that many calories for breakfast this morning! This is undoubtedly the most significant training challenge I have faced in recent years. How do you take a group of electricians or instrument technicians from volts, amperes, and time to calories per square centimeter (or, worse yet, Joules and millimeters) at a given working distance? Don’t blame it on the aptitude of the audience either. I received

28 much the same response from the audience at an IEEE meeting recently too! A thorough explanation is needed of the transition from watt-seconds (which most understand) through Joules (which some understand) to calories applied to square centimeters of bare skin (which no one understands). Such an explanation usually results in positive head nods or the “I get it!” looks. Of course, showing the gory electrical burn victim movies helps to drive home the point. I would hope that those engineers performing incident energy studies will keep in mind the target audience for the results. Providing a report in Joules per millimeter as well as recommendations for flame retardant materials with ratings of calories per square centimeter will only daze the confused. Help them out — provide some training along with the results of the incident energy study correlating study findings with minimum arc thermal performance values and maybe try to explain heat attenuation factor percentages too. 9. I have longer arms than you. Does that mean I can wear different flame retardant clothes? No, because I sweat more than you do… David K. Kreger has over 17 years’ experience with high-, medium-, and low-voltage power generation, transmission, and distribution systems. His formal education includes a BS in physics from New York State University and an AA from the University of Maryland. He gained extensive experience as a field engineer through testing, troubleshooting, commissioning, and repairing power systems as well as through high-voltage work as a utility lineman. He is a licensed power engineer, NETA Level III Certified Technician, member of the NFPA (electrical section), and master instructor for the training division of Emerson Electrical Reliability Services.

Arc Flash Safety Handbook — Volume 1

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Arc Flash Safety Handbook — Volume 1

Arc Flash Concerns NETA World, Fall 2004 Issue by Conrad St. Pierre Electric Power Consultants

Arc-flash energy is the latest hazard to receive muchneeded attention. While the arc flash hazard has been around for many years, it was not until 1982 that Ralph Lee proposed a method to quantify arc energy. In his paper, an equation defines the “safe” distance a worker can be from an arc without being excessively burned. Any curable burn or one that is not life-threatening he considered acceptable. Severe burns to the chest or head area he considered life-threatening. Severe arc flash burns can cause a slow, painful death. Hot gases can injure lungs and impair breathing. Even curable burns can result in painful skin and tissue injury that can take weeks to heal. Not all arc flash injuries are physical. Psychological effects such as depression, job apprehension, and family strife can also be present. Therefore, avoidance of any burn is important in terms of time, money, and a person’s well being. To improve electrical safety and to inform electrical technicians of the burn hazards of electrical arcs, wording was added to the 2002 National Electrical Code (NEC). The wording can be paraphrased as follows: “Flash protection is required when examining, adjusting, servicing, or maintaining energized equipment. The equipment shall be field-marked to warn qualified persons of potential electric arc flash hazards.” The 2002 and proposed 2003 revision of NFPA 70E states “Flash hazard analysis shall be done before a person approaches any exposed electrical conductor or circuit part that has not been placed in an electrically safe working condition. The flash hazard analysis shall determine the flash protection boundary and the personal protective equipment that people within the arc flash boundary must use.” While OHSA does not directly state what to do about arc flash hazard, the wording in OHSA 29 CFR 1910.132(d)(1) requires the employer to conduct and evaluate the workplace for hazards. Based on the employer’s assessment, the employer must select and require the use of appropriate

personal protective equipment (PPE). Since arc flash is a hazard, the above statement could easily be interpreted as requiring some means of quantifying and identifying the hazard to determine the appropriate PPE. Late in 2001, the IEEE working group for arc flash hazard was formed to quantify the energy released in an electric arc. Tests were made at voltages between 208 volts to 15 kilovolts. From these tests, empirical equations were developed to estimate the arc energy based on voltage, bolted fault current, distance, system grounding, and type of equipment where the arc is taking place. By the end of 2002, the IEEE Std.1584-2002 was available. This standard provides details of the calculation methods. While NFPA 70E gives some of the same equations as given in IEEE Std. 1584-2002, more detail is given in the latter. The focus of NFPA 70E and IEEE Std. 1584-2002 is the radiated heat or incident energy falling on a surface produced by an arcing fault. The incident energy generally used as a guide to restrict the flash hazard to a second-de2 2 gree or curable burn is 1.2 calorie/cm (1.2 calorie/cm = 2 2 5.02 Joules/cm = 5.02 Watt-sec/cm ). A bolted fault does not produce any radiated flash energy; therefore, any bolted short-circuit current calculation has to be translated to the maximum expected arc energy due to an arcing fault. IEEE Std. 1584-2002 provides the equations to do this. The three documents (NEC, NFPA 70E, and IEEE Std. 1584—2002) should be viewed as a working package for arc hazard exposure and personal protection.

Procedure for Arc Flash Hazard Calculations There are a number of steps in an arc flash calculation. The steps below are based on using IEEE Std. 1584-2002 equations. NFPA 70E also provides equations to determine the arc flash boundaries and energies, but the author believes the IEEE Std. 1584-2002 method is more exact. The steps are:

30 1. Using a single line diagram, determine the circuit impedances of cables, transformers, bus ducts, and other branch impedances. 2. Add to the network the source impedance of short-circuit contributors such as motors, generators, and utility connection. 3. Solve the network for the bolted short-circuit currents at the buses where electrical equipment exists or where electrical work is to be done. 4. From the bolted current, determine the expected 100 percent arcing current and 85 percent arcing current for the IEEE Std. 1584-2002 equations. 5. Using the protective device setting operating characteristics (curves), determine the total clearing time for the protective device based on the arcing current. 6. Based on the class of equipment [cable, switchgear, motor control center (MCC)], voltage level, and the expected working distance from the energized conductor to the person’s chest or head area, calculate the incident energy (calories/square centimeters) at 100 percent and 85 percent arcing current. Select the higher value. The incident energy equations are in IEEE Std. 1584-2002. 7. Based on the class of equipment (cables, switchgear, MCC), determine the flash protection boundary where onset of a second degree burn would occur. This is usually taken at 1.2 Cal/ 2 cm . The flash boundary equations are in IEEE Std. 1584-2002. 8. Voltage level determines several other distances that may be of interest. These are: • Limited approach boundary • Restricted approach boundary • Prohibited approach boundary. These distances are given in NFPA 2002. The voltage level also gives the voltage-rated PPE (gloves, tools, etc.) that should be used.

Arc Flash Safety Handbook — Volume 1 sible incident energy exposure for a person working on the 2 480-volt bus from 8.8 to 17.6 calories/cm . The risk hazard category for PPE is three in either case.

Table 1 — Summary of Arc Flash Calculations Location Main Feeder Fuse

Bolted kA 33.7 48.1 33.7 at 480V

Main Feeder Fuse

33.7 48.1 33.7 at 480V

100% Fault Arcing kA Time (Sec) 17.3 0.21 23.2 0.05 17.3 at 480V 0.42 85% Fault 14.3 0.30 19.7 0.05 14.3 at 480V 1.0

2

Cal/cm 4.4 1.4 8.8 5.3 1.2 17.6

Commercial power system software can greatly reduce the burden of finding short-circuit currents, protective-device operating times, and the arc flash calculations. The arc flash calculations can be part Figure 1 — Curve to Determine Protective Device Operating Times of the software package. The IEEE Std. 1584-2002 includes an arc flash calculation spreadsheet that can be used once the short-circuit calculations are made IEEE Equations and Test Results and relaying times are known. for Open Arcs Table 1 and Figure 1 show the information used to calculate the incident energy for the diagram shown in Figure The equations given in IEEE Std. 1584-2002 are based on 1. If this system did not have a secondary main breaker, the experimental 208-volt to 15.0-kilovolt testing and results. fuse at 4.16 kilovolts would clear the fault on the 480-volt Three sets of equations are provided for voltage ranges of bus. Because of the fuse characteristics, the fault clearing 208 to 1000 volts, 1001 to 15,000 volts, and >15,000 volts. time at 85 percent arcing current is more than twice as long The empirical equations given in the standards for voltages as the time for a 100 percent fault. This increases the posup to 1000 volts tend to give the higher limits of energy

Arc Flash Safety Handbook — Volume 1

31

radiated from the test arcs. The actual radiated energy could be higher than the values given from the equations. The environment in which the arc takes place affects the arc. Factors such as humidity, power factor, contaminants, temperature, enclosure, length of an arc, impedance of an arc, duration of an arc, and material consumed in the arc will affect the radiated energy. Figure 2 shows the plot of the developed equations given in the IEEE Std. 1584-2002 reference to the test data for 600-volt tests for an open-air arc. An open arc is one where heat is radiated in all directions. A fault on a cable in an open tray could be considered an openair arc. The calories/square centimeter incident energies in this figure are based on a surface located 24 inches (61 centimeters) away from the arc and for a 1.0 second fault duration. The curve labeled “IEEE 1584 Equations” is derived Figure 2 — Comparison of IEEE Equations to 600-Volt Open-Air Arc Test Data (IEEE 1584 Equations, based on 24 Inch to Subject, 1.25 Inch Arc Gap, 1.0 Second Exposure) from IEEE Std. 1584-2002 Equations 1 to 6 for an arc gap of 1.25 inches (32 centimeters). IEEE Std. 1584-2002 also provides an equation based on Ralph Lee’s method. This equation is used for voltages greater than 15 kilovolts until future tests are done at higher voltages. The curve labeled ‘IEEE Lee’s Method’ is from an equation based on an adjustment to Lee’s work. It is shown for comparison with the IEEE Std. 1584-2002 equations and test data. Lee’s method is simpler and more conservative, since it calculates the incident energy without knowing the arc gap or the arcing current. The IEEE Std. 1584-2002 equations calculate an estimated arc current from the bolted fault current and arc spacing. These values are then used to calculate the incident energy. At 600 volts, IEEE Std. 1584-2002 equations and IEEE Lee’s Method equation follows the higher incident energy test values. Figures 3 and 4 show the relationship of the IEEE Std. 1584-2002 equations and IEEE Lee’s method equations to the test data. In this case, some of the test data points are significantly above the IEEE Std. 1584-2002 equations. In Figure 3 — Comparison of IEEE Equations to 4160-Volt Open-Air Arc Test Data (IEEE 1584 Equations, based on 24 Inch to Subject, 4.0 Inch Arc Gap, 1.0 Second Exposure) the calculations of incident energy for systems greater than 1000 volts, the study engineer may desire to increase the calculated values by a factor of 2.0 to Enclosed Arcs insure a safety margin or change Cf (in IEEE Std. 1584-2002 Much of the work around energized equipment is of the Equation 6) to 2.0 for voltages greater than 1000 volts. metal, enclosed type. The energized conductors are normally While using the methods in NFPA 70E or IEEE Std. enclosed behind removable panels or doors. An arc in these 1584-2002 does not insure that burns from an arc flash will areas is considered “in a box” or “in an enclosure” and will be not injure a worker, it indicates that the worker has taken more intense and directed. The “in an enclosure” measuresteps to reduce the risk of injury. Following the NFPA 70E ments made by the IEEE Std. 1584-2002 working group procedures and wearing the proper protective equipment gave incident energy intensity two to four times higher than will greatly reduce the possibility of burns. Using the inciarcs in open air. The equations given in IEEE Std. 1584-2002 dent energy equations, it is expected that the PPE per the have constants accounting for fault in enclosures based on tables in NFPA 70E will be adequate for 95 percent of the MCC or switchgear size cubicles. test results used to develop the equations.

32

Arc Flash Safety Handbook — Volume 1

Figure 4 — Comparison of IEEE Equations to 13,800-Volt Open-Air Arc Test Data (IEEE 1584 Equations, based on 24 Inch to Subject, 6.0 Inch Arc Gap, 1.0 Second Exposure)

Table 2 - Minimum Thermal Protection Recommended (Based on proposed updates to NFPA 70E) Flash Hazard Risk Category 0

Range of Calculated incident energy 0-1.2 cal/cm2

Min. PPE Rating

Clothing Required

N/A

1 2

1.2+ to 4 cal/cm2 4+ to 8 cal/cm2

4 cal/cm2 8 cal/cm2

3

8+ to 25 cal/cm2

25 cal/cm2

4

25+ to 40 cal/cm2

40 cal/cm2

5

40+ to 100 cal/cm2

100 cal/cm2

4.5-14.0 oz/yd2 untreated cotton FR shirt and pants Cotton underclothing plus FR shirt and pants Cotton underclothing plus FR shirt, pants, overalls or equivalent Cotton underclothing plus FR shirt, pants, plus double layer switching coat and pants or equiv. Cotton underclothing plus FR shirt, pants, plus multi-layer switching suit or equivalent

FR = Fire resistance fabric

Personal Protective Equipment The purpose of these calculations is to determine which PPE limits the possible thermal energy exposure to the critical body parts such as face and chest areas. Usually the calculations give the possible heat exposure level in calories/square centimeters or Joules/square centimeters. Knowing the heat exposure level, the desired protective

clothing can be chosen. Table 2, based on NFPA 70E data, provides this cross-reference. Gloves rated for the voltage class, insulated tools, and face shields will be required for some work tasks around energized equipment. NFPA 70E provides guidelines for PPE required for different work 2 tasks. Burns from energy levels less than 1.2 calories/cm are curable for most persons.

33

Arc Flash Safety Handbook — Volume 1 Arc Blast Pressure Another item associated with an electric arc is the blast energy, or pressure, which is not presently covered in NFPA 70E or IEEE Std. 1584-2002. This force can be significant and can blow workers away from the arc, causing falls and injuries that may be more severe than the burns. In Ralph Lee’s 1987 paper, he sites several case histories. In one case, with approximately 100-kiloampere fault level on a 480volt system, an electrician was somersaulted 25 feet away from the arc. Being forced away from the arc reduces the electrician’s exposure to heat radiation and molten copper, but can subject him or her to falls or impact injuries. The approximate initial impulse force at 24 inches for a 100kiloampere bolted fault (approximately 42 kiloampere arc) was calculated to be approximately 260 pounds per square foot, as determined from the equation below: 2 11.5*kA arc Pounds/Ft = 0.9 (Distance from arc in feet)

Limiting Arc Exposure Incident energy increases with time and fault current. Reducing either or both lowers the incident energy due to an arcing fault. Incident energy can be reduced by system design or operating procedures. It is best to work on de-energized equipment, but this may not be possible. The following are some means of reducing incident energy: 1. On new or retrofitted breakers with electric close and trip control, place the close/open control switch on a remote or nonbreaker panel.

cycles, thereby reducing the exposure time. The incoming main breaker, in order to be time-coordinated with the feeders, generally will not have an instantaneous enabled on the protective device. The fault clearing time could be in the range of 0.2 to 1.0 second. This long time greatly increases the arc exposure time and amount of radiation a worker would receive if the arc blast pressure were not enough to propel the worker away from the fault. To limit the arc exposure on buses where the protective devices are time-coordinated, the main breaker shown in Figure 5 could be ordered with an instantaneous protective device and a safety switch. Normally the instantaneous protection would not be functional due to the open contact of the safety switch. However, when work is being done on the energized equipment, the safety switch would be turned “ON,” thus limiting the arc exposure to the worker should an arcing fault accident occur. The time-selective system would be eliminated for duration of the work in the interest of safety. Electronic-trip low-voltage breakers could have either their short-time or instantaneous pickup setting lowered when work is being done on the equipment. Some manufacturers have a disable function on the low-voltage instantaneous adjustment which would be useful on incoming main breakers. The instantaneous adjustment would be disabled for a selective system under normal operation and placed in service for reduced arc-fault exposure when working on the equipment.

8. While not a way to reduce arc incident energy, it is good practice to use a buddy system. In the event some incident should happen, help can be summoned quickly if a second person is around.

2. If possible, use a remote or longer operating arm when racking in or opening/closing breakers. 3. Place a barrier between the technician and the device being placed in service or racked in. 4. Review protective devices to see if they can be lowered in time and pickup. 5. When working with double-ended load centers or substations with a normally closed tie, open an incoming breaker or the tie breaker to reduce the fault level.

6. Review protective fuse sizes. Smaller fuses reduce the exposure time. This can be significant when the arcing current or 85 percent of arcing current is not in the current limiting range. 7. Change relay settings when working on equipment. For many load centers, both high and low voltages, the feeders have instantaneous protective devices that operate and clear the fault in one to eight

Figure 5 — Schematic to Control Arc Exposure on Relayed Breakers

34 Calculation Means The calculations for arc flash incident energies and boundary distances can be accomplished a number of ways. The reader can use the equations in IEEE Std. 1584-2002 after obtaining the bolted three-phase, short-circuit cur® rent and clearing times. IEEE also has made an EXCEL spreadsheet program available with these equations for approximately $500. The user enters the fault level, voltage, clearing time, and distance from an expected arc to the worker. The program then provides the incident energy and boundary distance. The user would use this data to make the labels to be placed on the electrical equipment. Software companies providing industrial-based electrical system analysis have arc flash hazard packages integrated with their short-circuit and protective device packages.

References IEEE Std. 1584-2002, IEEE Guide for Performing Arc Flash Hazard Calculations, New York, NY, 2002. Lee, R, “The Other Electrical Hazard: Electric Arc Blast Burns,” IEEE Transactions on Industry Applications, Vol. 1A-18, No. 3, May/June 1982. Lee, R., “Pressures Developed by Arcs,” IEEE Transactions on Industry Applications, Vol. 1A-23, No. 4, July/August 1987. National Electrical Code, Article 110.16, 2002, National Fire Protection Association, Quincy, MA, 2002. NFPA 70E Standard for Electrical Safety Requirements for Employee Workplaces, National Fire Protection Association, Quincy, MA, 1995. OSHA 29 CFR 1910.132(d)(1), Occupational Safety and Health Standards for General Industry, Part 1910, U. S. Department of Labor, Occupational Safety and Health Administration. Copies of the NEC, NFPA 70E, and IEEE Std. 15842002 references can be purchased from their parent standard organization. Conrad St. Pierre is a graduate of the University of Maine with a BS in electrical engineering and a certificate in power system engineering. He received a MS from Union College in Schenectady, New York. Prior to forming Electric Power Consultants in 1997, he was employed by General Electric and Industrial Power Systems. He has been a member of IEEE and of several subcommittees and served as Chair of the Violet Book working group, dealing with short-circuit calculations. He is a member of the IEEE-1584 Arc Flash working group. He was a member of the US National Committee of the International Electrotechnical Commission Technical Advisory Group for TC73/WG1 and WG2 concerning short-

Arc Flash Safety Handbook — Volume 1 circuit currents and calculation methods. In 2001, he finished a book, A Practical Guide to Short-Circuit Calculations. Electric Power Consultants, LLC, provides analytical engineering services to his clients and to clients of GE, ABB, PTI, Hanson Engineers, and ANNA, Inc.

35

Arc Flash Safety Handbook — Volume 1

Six Steps to Arc Flash Nirvana NETA World, Fall 2004 Issue by Jim White Shermco Industries

In the electrical industry the phrase “arc flash” is generating a lot of interest. Many managers and supervisors are asking “Why?” More to the point, many are saying, “I don’t see how this affects me or my people. We have never had an arc flash incident.” If this is true, then what is all the fuss about?

Statistically Speaking At the 11th Annual IEEE-IAS Electrical Safety Workshop, Cawley and Homce of the Center for Disease Control (CDC)/National Institute of Safety and Health (NIOSH) presented statistics showing that during the period from 1992 through 2001 there were 44,363 electrically-related injuries. The number of nonfatal electrical shock injuries was 27,262, and 17, 101 injuries were caused by electric arc flash burn. Figure 1 is one of the slides presented during that presentation. In statistics presented at the 3rd International Conference on Electrical Injury in 1998, the Electric Power Nonfatal electrical accidents involing days away from work, 1992-2001 Industry Industry

5,056 1,078

Transportation and public utilities

Electric shock Electric burns

478

Retail trade Wholesale trade

2,324

Construction

0

3,513

6,579

Manufacturing

Agriculture

1,012

992

1,895

Mining

2,216

5,282

Finance, insurance, and 795 real estate

5,884

5,990

212 169 296

N = 44,363 Electric shock = 27,262 Electric burns = 17,101

60

2,000

4,000

6,000

No. of accidents Some data not meeting BLS publication criteria may not be shown. Data may not sum to totals

Figure 1

8,000

10,000

12,000

Source BLS.SOII

Research Institute estimated the direct costs of an electrical fatality at $1.3 million dollars, with total direct and indirect costs reaching between four and ten million dollars. Serious electrical injuries can be even more devastating to the people involved as well as to the bottom line. Floyd estimated the total of direct and indirect costs of a major electrical accident at $17.4 million in 2003 dollars. Using the above estimates of costs related to an electrical injury or death, the sum can have a very serious effect on a company’s ability to function. There are also the additional costs for trained personnel to be away from the job recovering from an electrical accident: lost production, increases in workman’s compensation and insurance rates, possible OSHA fines, legal fees — the list goes on and on. This does not take into account the pain, suffering and emotional costs which cannot be measured. Another fact brought out by the CDC/NIOSH study is that electrical burn injuries cause a longer stay away from the job site. (See Figure 2.) Note that, even though burns accounted for only 38 percent of the total injuries, they caused a disproportionate number of days lost from work. If we try to match the figures given in the CDC/NIOSH study with those in the Bureau of Labor Statistics (BLS) website, we will find that we cannot. Many of the numbers quoted by the CDC/NIOSH study are not available to the general public, so the numbers used do not match up with numbers posted on the BLS website. The BLS site is somewhat limited in the data sorting it can do, whereas CDC/NIOSH has access to the complete database. Other important facts in that study: In the electrical construction industry, 80 percent of electrical injury victims are electrical workers, not laborers or helpers. • Small companies (fewer than 10 employees) had a disproportionate number of electrical injuries. Figure 3 illustrates company size vs. percent injury. •

36

Arc Flash Safety Handbook — Volume 1 shall use.” So, Step 1 on the list is to determine if the work being done is within the FPB. The FPB can be calculated using the equations given in 70E or by using one of many available software programs, both freeware and commercial. Cooper-Bussmann has a calculator imbedded in its website that will do the job and is free, although calculations must be performed on the website. In many cases, especially where the available short-circuit current is 10,000 amperes or less, the FPB may only be a few inches. Some examples of low-energy FPBs (all using 9,600-ampere available short-circuit current and protected by a molded-case circuit breaker) are shown as follows:

Median days away for electrical shock and burn injuries, all industries, 1992-2001

25

20

Burns Shocks

Days

15

10

5

0

1992

1993

1994

1995

1996

1997

1998

1999

2000

Year

2001

480 volts — three-phase 277 volts — single-phase • 208 volts — three-phase • 120 volts — single-phase •

Source: BLS. SOII

•

Figure 2 •

Most injuries occur more than six hours into the work shift.

By spending a small amount of time to research this data on the BLS website, management can begin to determine how their company matches up with general industry as a whole and with others in the same industry. Rates per 10,000 workers are also available on the site and may be easier to compare. Company size of electrical victims employed by electrical contractors, 1992-2000 50%

Percent

40% 30% 20%

10%

9%

10% 0%

18%

14%

1 to 10

11 to 19

In these instances, correct PPE would be voltage-rated gloves and protectors, safety glasses or goggles, 12 ounces per square yard cotton or flame retardant clothing, and safety shoes. The key in these examples is that the available short-circuit current is less than 10,000 amperes. If a circuit is fed by an AWG 12 or less wire and is supplied by a general-purpose circuit breaker or fuse (10,000-ampere interrupting rating), it would match the above figures. If the short-circuit available current is higher, the FPB will increase as well. More PPE would be required to match the hazard.

Step 2: Gather the Information

N = 359

39%

The next step is to gather the information needed to perform the calculations. Several pieces of information are required, including: •

10%

• 20 to 49

50 to 99

Company size (no. of employees)

100+

7.1 inches 4.1 inches 4.7 inches 2.7 inches

Not reported Source: BLS. CFOI

Only cases reporting establishment size, SIC, and nature of injury are shown

Figure 3

Step 1: Determine the Flash Protection Boundary and Personal Protective Equipment Now that the need has been established, what does a company need to do? In the area of arc flash protection, the first thing is to determine if a danger exists. NFPA 70E, “Standard for Electrical Safety in the Workplace,” states in Article 130.3, “A flash hazard analysis shall be done in order to protect personnel from the possibility of being injured by an arc flash. The analysis shall determine the Flash Protection Boundary (FPB) and the personal protective equipment [PPE] that people within the Flash Protection Boundary

• • • •

Available short-circuit current at the point of fault Nominal voltage Maximum total clearing time of the protective devices Working distance Type of ground system being used Type of protective device (including model numbers and settings)

This is the same information that is derived from the short-circuit analysis and coordination study. It is important that this information is correct and up-to-date or subsequent steps will be pointless.

Step 3: Perform an Arc Flash Study This third step calculates the incident energy that would be received by the worker at the point of contact. The IEEE Guide 1584-2002 can be used to determine the FPB, the incident energy at working distance, and the PPE required. It is used as a plug-in for many of the available engineering

37

Arc Flash Safety Handbook — Volume 1 software packages on the market. The incident energy provided by the spreadsheet calculator will be given in calories per square centimeter and needs to be reviewed to determine if adequate PPE is available and must be documented. Figure 4 shows a screenshot of the SKM software package used by Shermco Industries when performing arc flash studies. The FPB, working distance, and incident energy are all detailed. Also given is the NFPA Hazard Risk Category (HRC) required for the worker. If the incident energy is too great, it is flagged and highlighted on the spreadsheet. One of the issues that arises when performing these calculations is that of the working distance. IEEE 1584 provides recommended working distance for use in its calculations, but in real life people are not so precise. A change of just a few inches can make a tremendous difference in the incident energy received by the worker. Often, increasing the distance by six inches from the component or part to the worker reduces the incident energy 30 percent or more. This cannot be applied in many situations but can be for tasks such as racking circuit breakers in and out of their cubicle. Longer racking handles or remote racking devices can be used to decrease incident energy to a tolerable level.

for the same heat as the rest of the PPE, and some lowdollar providers of PPE sold substandard face shields. This was resolved in the 2004 revision of 70E which requires that the face shield provide the same arc rating as the rest of the flash protection. According to NFPA 70E, incident energy received by 2 the worker must be reduced to no more than 1.2 cal/cm . As an example, holding one’s finger over a match for one 2 second produces an incident energy of 1.0 cal/cm , while 1.2 2 cal/cm is considered to be the amount of heat required to produce onset of a second-degree burn on unprotected skin. Even though the worker wears arc flash protective equipment, he can still receive burns if the heat is high enough. The heat passing through the PPE can be high enough to melt the elastic in undergarments. A good rule-of-thumb is to use PPE with an arc rating equal to or greater than the calculated incident energy.

Step 5: Mark the Equipment The 2002 revision of NFPA 70, commonly known as the National Electrical Code, requires that new equipment be field-marked to warn of the hazards if the cover is removed. This is stated in Article 110.16:

Step 4: Choose the Correct PPE Correct PPE selection is critical to protecting the worker. After performing the incident energy calculations, the derived calories per square centimeter must be compared with the PPE being considered. Prior to the year 2000, there were no markings on flash protective equipment to show its arc rating. After that date the NFPA 70E required that PPE used as arc flash protection be marked with the arc rating in calories per square centimeter on the label. Unfortunately, 70E did not specify that the face shield material be rated Bus Name

Protective

Bus

Bus

Prot Dev

Prot Dev

Trip/

Breaker

Device

kV

Bolted

Bolted

Arcing

Delay

Opening

Fault

Fault

Fault

Time

Time

Name

“Flash Protection. Switchboards, panelboards, and motor control centers in other than dwelling occupancies, that are likely to require examination, adjustment, servicing, or maintenance while energized, shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment. Ground

Equip

Gap

Type

Arc Flash

Working

Incident

Required Protective

Boundary

Distance

Energy

FR Clothing Class

(in)

(in)

(cal/cm2)

(kA)

(kA)

(kA)

(sec.)

(sec.)

11USS13.8kV LD

11USS HVFU

13.8

18.08

17.91

17.21

0.01

0

No

SWG

153

9

36

0.30

Class 0

11USS13.8kV LN

SR750 11USS

13.8

18.08

17.91

17.21

0.016

0.083

No

SWG

153

92

36

2.97

Class 1

12USS13.8kV LD

12USS HVFU

13.8

22.79

21.55

17.53

0.08

0

No

SWG

153

80

36

2.60

Class 1 (*3)

12USS13.8kV LN

SR750 12USS

13.8

22.79

21.55

20.63

0.02

0.083

No

SWG

153

122

36

3.91

Class 1

13USS 103B LD

13USS 103B

0.48

60.56

57.65

26.87

0.05

0

No

SWG

32

56

24

4.20

Class 2

13USS 103C LD

13USS 103C

0.48

60.56

57.65

26.87

0.05

0

No

SWG

32

56

24

4.20

Class 2

13USS 103D LD

13USS 103D

0.48

60.56

57.65

26.87

0.05

0

No

SWG

32

56

24

4.20

Class 2

13USS 104B LD

13USS 104B

0.48

60.56

57.65

26.87

0.05

0

No

SWG

32

56

24

4.20

Class 2

13USS 104C LD

13USS 104C

0.48

60.56

57.65

26.87

0.05

0

No

SWG

32

56

24

4.20

Class 2

13USS 13.8kVLD

13USS HVFU

13.8

19.25

18.86

18.1

0.01

0

No

SWG

153

9

36

0.32

Class 0

13USS 13.8kVLN

SR750 13USS

13.8

19.25

18.86

18.1

0.016

0.083

No

SWG

153

97

36

3.15

Class 1

13USS 480V BUS

13USS MAIN

0.48

60.56

45.99

18.22

0.652

0

No

SWG

32

246

24

36.8

Class 4 (*3)

13USS MAIN LN

13USS HVFU

0.48

60.56

45.99

21.44

2

0

No

SWG

32

583

24

131

Dangerous!!!

Figure 4

38

Arc Flash Safety Handbook — Volume 1

FPN No. 1: NFPA 70E-2000, Electrical Safety Requirements for Employee Workplaces, provides assistance in determining severity of potential exposure, planning safe work practices, and selecting personal protective equipment. FPN No. 2: ANSI Z535.4-1998, Product Safety Signs and Labels, provides guidelines for the design of safety signs and labels for application to products.” This applies to all equipment installed after January, 2002. Why should any company worry about labeling? OSHA has a multiemployer worksite policy (CPL2-0.124) that makes it clear that the equipment owner is just as responsible for contractor safety as the contractor is. If a company allows the contractor on its job site, that company has approved the contractor’s safety procedures and policies. Because of this, the smart move for any company is to be proactive, especially where known hazards exist. Employees as well as contracted workers can not always be counted on to know the methods and reasons of arc flash protection. Many workers lack the training and knowledge needed to choose the right PPE accurately. Labeling the equipment ensures that those who work on power system equipment will be aware of the shock and arc flash hazard involved and the required flash protective equipment. An example label is shown in Figure 5.

Step 6: Train the Workers OSHA and NFPA 70E require that workers be qualified in order to work on or near energized electrical systems. “Qualified” is defined in 29CFR1910.399 as “one who is familiar with the construction and operation of the equipment and the hazards involved.” Further, 29CFR1910.331(a) states, “The provisions of 1910.331 through 1910.335 cover electrical safety-related work practices for both qualified persons (those who have training in avoiding the electrical hazards of working on or near exposed energized parts) and unqualified persons (those with little or no such training) working on, near, or with the following installations:” [a list of facilities is then given]. This statement requires that qualified workers also be trained in how to avoid the hazards. 29CFR1910.269 has similar requirements for those working on systems rated above 600 volts. In order for the arc flash study to be effective, workers must be trained in what the labels mean and how to apply the information on them. One of the first things OSHA does during a site inspection or an accident investigation is to review the training records for that company. Lack of training is often cited as a reason for large fines that come soon afterward. Who needs training? Almost everyone needs training. Unqualified workers must be trained on the hazards of electricity and how to avoid them. Qualified workers must meet the above requirements and other specific requirements given in 29CFR1910.332 and -.269. Many companies providing on-the-job (OJT) training do a poor job of documenting that training. OSHA will accept OJT, but if a company doesn’t document it, it may as well never have happened. Documentation includes date, name of attendee, and topic covered as well as initials or signature of attendee verifying he actually took the OJT.

NFPA 70E

Figure 5

NFPA 70E has been mentioned a number of times in this paper. It is important for companies to have a copy of this document. In 1979, OSHA asked the NFPA to develop a consensus standard they could use to write the regulations. OSHA has two nonvoting members on the 70E Committee to ensure it stays consistent with the regulations. In fact, NFPA is conducting seminars for OSHA Compliance Officers on how to use 70E when writing citations. OSHA has used 70E as justification for these citations in court, and the court has upheld that practice. One of the best features of 70E is the set of tables labeled “Table 130.7.” These tables are helpful in choosing what PPE would be required for standard tasks performed by electrical workers. Figure 6 shows a partial view of Table 130.7(C)(9)(a), “Hazard/Risk Category Classifications.” Each general type of equipment is grouped and common tasks are listed. Each task is assigned a Hazard/Risk Category number (HRC) from HRC0 to HRC4, with HRC4 being the highest. For example, “insertion or removal (racking) of CBs from cubicles, doors closed” (on 600V Switchgear) shows an HRC 2, while the same action with open doors rates an HRC3. It is critical that the notes at the

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Arc Flash Safety Handbook — Volume 1

Figure 6

Figure 7

40 bottom of each table be reviewed and understood. The tables cannot be used outside of the stated limitations; otherwise, injury or death could result. Table 130.7(C)(10) in Figure 8 shows a partial list of PPE required for the various HRCs. This would be used in conjunction with Table 130.7(C)(11), “Protective Clothing Characteristics” shown in Figure 9. A change has been made to 70E Table 130.7(C)(9)(a), even though the standard has only been out since April of this year. Some of the notes at the bottom of the table have been revised as follows: Note Number Changes Made (In Italics) 1 Maximum of 25-kiloampere short-circuit current available, 0.03 second (two-cycle) fault clearing time. 2 Maximum of 65-kiloampere short-circuit current available, 0.03 second (two-cycle) fault clearing time. 4 Maximum of 42-kiloampere (from 65-kiloampere) short-circuit current available, 0.33 second (20-cycle) fault clearing time. 5 Maximum of 35-kiloampere (from 65-kiloampere) short-circuit current available, up to 0.5 second (from 1.0 second) (30-cycle) (60-cycle) fault clearing time. Corresponding changes were made within the table to reflect the changes in the notes.

Summary An electrical accident can have far-reaching and severe negative aftereffects. As much as anything else, the litigation that will follow diverts needed resources and hurts morale. Most companies are already pressed for manpower and time. Adding the burden of an arc flash study, coupled with the time and expertise involved in performing it, can be a daunting task. Many companies offer arc flash studies and will handle everything from calculations to marking equipment to training. One last thought on this topic: electrical equipment maintenance. All ratings and calculations are performed with the expectation that protective devices will function correctly, are correctly coordinated, and are set to that coordination study. Our experience has been that this often is not the case. In nearly every facility in which we work, there are breakers and switches that are too slow or nonfunctional due to lack of maintenance. This may increase the time of exposure to an arc from four to six cycles to one to three seconds, or even longer if the next upstream device is required to clear the fault. Under these circumstances, there is no protective equipment that could protect a worker. Adequate maintenance is as critical to safety as the selection of PPE.

Arc Flash Safety Handbook — Volume 1 References 1. ANSI/NFPA 70, National Electrical Code, 2002. 2. ANSI/NFPA 70E, “Standard for Electrical Safety in the Workplace,” April, 2004. 3. Bureau of Labor Statistics website, www.bls.gov. 4. Cawley, James, PE and Homce, Gerald T., “Occupational Electrical Injuries in the United States and Recommendations for Safety Research,” Journal of Safety Research 34, 2003, pp. 241—248, 11th Annual IEEE Electrical Safety Workshop. 5. Electric Power Research Institute, 3rd International Conference on Electrical Injury. 1998. 6. Floyd , H. Landis, “Facts on Electrical Incident and Injury Costs,” 11th Annual IEEE Electrical Safety Workshop. 7. IEEE 1584-2002, “Guide for Performing Arc Flash Calculations.” October, 2002. 8. OSHA 29CFR1910.331 - .335, Subpart S, “Electrical Safety-Related Work Practices.” 9. OSHA 29CFR1910.269, Subpart R, “Electric Power Generation, Transmission and Distribution.” Jim White is currently the Training Director for Shermco Industries, a NETA Accredited Company. Jim represents NETA on the NFPA’s 70E Committee as the Alternate and is a Level IV certified technician. Jim has spent the last twenty years directly involved in technical skills and safety training for electrical power system technicians.

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Arc Flash Hazards to Be Studied NETA World, Winter 2004-2005 Issue by Ron Widup and Jim White Shermco Industries

The IEEE and NFPA have announced formation of a new Arc Flash Hazard Work Group (9/13/04). This work group is to review existing information relating to the thermal effects of an arc and provide accurate and verifiable data. In addition, this work group, unlike the IEEE P1584 work group, will consider other hazards created by a fault, including pressure wave (arc blast) and acoustic effects. The IEEE/NFPA Steering Committee established a Research and Test Planning Committee (RTPC) to develop a research and test plan that will provide data on the nature of electrical arcs. The objectives of the committee are:

1. Develop a research and test plan to predict the various forms of energy to which a person might be exposed during an arc. 2. Verify existing protocols or generate new protocols to measure the effects of an arc. 3. Develop a scientific relationship between electrical characteristics and hazard characteristics of an arc to develop directly usable data. 4. Define the mechanisms of thermal energy transfer from an arc to the surrounding area and the relationship of each to potential injury.

5. Provide adequate and scientifically verifiable data to the IEEE and NFPA standards and code processes to enable the development of effective safeguards for arc flash hazards.

6. Develop a testing process to determine the intensity of ultraviolet, infrared, x-ray, and any other potentially injurious energy bands emitted during an arc as well as to determine the potential for injury from each. 7. Determine the impact of equipment installed within an enclosure on existing data related to an arc-in-the-box or develop new information.

As the test parameters and instrumentation (to be defined by the RTPC) are defined, the RTPC will give special consideration to the following factors:

• Location of the arc within the equipment

• Orientation of the arc within the equipment • Capacity of the electrical system

• Protective devices and components normally provided in a system • Electrical equipment normally found in the field

NETA is a contributor for this project, and Jim White (Shermco Industries) is NETA’s representative on the work group. NETA is always looking for ways to further safe working conditions for member companies and their employees and has representatives on the NFPA 70E Committee as well as various NFPA, NEC, IEEE, and ANSI committees. The hazard of pressure waves created by electrical arcs is one that has not been fully investigated. While fewer injuries and fatalities from the pressure wave are believed to occur than from the hazard of shock or arc flash, once this pressure wave hazard is studied and quantified in the same manner as the thermal effects of an arc, protective measures for the pressure wave can be established. Either new personal protective equipment can be developed or existing personal protective equipment can be shown to be adequate for this hazard. th At a presentation given at the 11 Annual IEEE/IAS Electrical Safety Workshop, it was stated that projectiles from exploding electrical equipment can reach speeds of 700 miles per hour. The result of being hit by such an object, plus other hazards such as molten metal and arc plasma vapor, can cause serious injury or death. The study and analysis of this hazard phenomenon are crucial for the continuous improvement of a safer work place. We will keep you updated as the information develops. Be safe. Ron A. Widup and Jim White are NETA’s representatives to NFPA Technical Committee 70E (Electrical Safety Requirements for Employee Workplaces). Ron is past president of NETA and currently a member of the Board of Directors and Standards Review Council. Both are employees of Shermco Industries.

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Arc Flash Safety Handbook — Volume 1

Electrical Hazards Analysis PowerTest 2005 (NETA Annual Technical Conference) Dennis K. Neitzel, C.P.E. AVO Training Institute, Inc

Introduction The subject of electrical hazards analysis has been recognized by a small segment of the electrical industry for many years. The petrochemical industry and many government institutions have performed research on this subject for over twenty years. For the most part however, the electrical industry, at least at the user level, has largely ignored the subject, essentially reacting to catastrophic accidents, rather than proactively trying to predict and prevent them. Recent changes in consensus standards, along with a better general understanding of the seriousness of electrical hazards have resulted in a renewal of interest in the subject. As the awareness of electrical hazards increases many are puzzled by phrases like; “Limited Approach Boundary,” “Restricted Approach Boundary,” “Prohibited Approach Boundary,” and “Flash Protection Boundary.” Understanding these terms is important to understanding shock and arc flash hazard protection. Below are the definitions of these terms as found in NFPA 70E-2004, Article 100: [1] Limited Approach Boundary- “An approach limit at a distance from an exposed live part within which a shock hazard exists.” Restricted Approach Boundary- “An approach limit at a distance from an exposed live part within which there is an increased risk of shock, due to electric arc over combined with inadvertent movement, for personnel working in close proximity to the live part.” Prohibited Approach Boundary- “An approach limit at a distance from an exposed live part within which work is considered the same as making contact with the live parts.” Flash Protection Boundary- “An approach limit at a distance from exposed live parts within which a person could receive a second degree burn if an electrical arc flash were to occur.”

Li mited Appr oach B oundar y

Re str icted Appr oac h B oundar y Cr itical poin t or I nitia tion of a rc Pr ohibi ted Ap pr oach B oundar y

Flash Pr otection B oundar y

Illustration of Boundaries

The NFPA 70E-2004, “Standard for Electrical Safety in the Workplace”, addresses the requirements for conducting an “Electrical Hazard Analysis” with emphasis on the “Shock Hazard Analysis” and the “Flash Hazard Analysis”. NFPA 70E-2004 tells us that if circuits, operating at 50 volts or more, are not deenergized (placed in an electrically safe work condition) then other electrical safety-related work practices must be used. These work practices must protect the employee from an arc flash, as well as inadvertent contact with live parts operating at 50 volts or more. These analyses must be performed before an employee approaches exposed live parts, within the Limited Approach Boundary. This paper will provide an overview of the principle types of electrical hazards analysis, along with a discussion of the relevant standards and regulations pertaining to the subject.

Shock Hazard Analysis Each year several hundred workers are injured or killed due to inadvertent contact with energized conductors. Surprisingly, over half of those killed are not in tradition electrical fields (i.e. linemen, electricians, technicians, etc.), but are from related fields such as painters, laborers, and drivers. [Detailed surveillance data and investigative reports

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Arc Flash Safety Handbook — Volume 1 of fatal incidents involving workers who contacted energized electrical conductors or equipment are derived from the National Traumatic Occupational Fatalities (NTOF) surveillance system maintained by the National Institute for Occupational Safety and Health (NIOSH)]. Because of this, NFPA 70E-2004 established a new requirement for conducting a “Shock Hazard Analysis” in order to determine the voltage that a person would be exposed to, shock protection boundaries, and personal protective equipment requirements. Investigations into the causes of injuries and fatalities point to several contributing factors [2]: • Faulty insulation; • Improper grounding; • Loose connections; • Defective parts; • Ground faults in equipment; • Unguarded live parts; • Failure to deenergize electrical equipment when it is being repaired or inspected; • Intentional use of obviously defective and unsafe tools; or • Use of tools or equipment too close to energized parts.

• Only qualified persons are permitted within these boundaries. • Unqualified person may not enter these boundaries unless the conductors and equipment have been placed in an electrically safe work condition.

Industry Recognized Good Practices • Plan every job. • Anticipate unexpected results and the required action for these results. • Use procedures as tools. • Identify the hazards. Keep unqualified workers away from these hazards. • Assess employee’s abilities. Remember, there is a difference between ten years of experience, and one year of experience repeated ten times. In addition to the assessment of work practices, the shock hazard analysis must include an assessment of the physical condition of the electrical system. The assessment must also identify the proper PPE for shock protection, which would include, but not be limited to, rubber insulating gloves with leather protectors, rubber blankets and mats, and insulated hand tools.

These factors form the basis for a shock hazard analysis. To appropriately assess the electrical shock hazard associated with any type of maintenance or repair work, it is necessary to evaluate the procedures or work practices that will be involved. These practices should be evaluated against both regulatory and consensus standards requirements as well as recognized good practice within the industry. These principles are summarized below.

OSHA Regulatory Requirements

Insulated Tools and Rubber Insulating Gloves

• All equipment must be placed in a deenergized state prior to any maintenance or repair work. (limited exceptions exist).[3][4] • The deenergized state must be verified by a qualified person prior to beginning any work.[3] • The deenergized state must be maintained through the consistent use of locks and tags, and in some cases, grounding.[3][4][5] • When energized work is performed, it must be performed in accordance with written procedures.[3][6]

Another consideration is the continuity and low resistance of the equipment grounding system, which is a major concern. Of equal importance is to insure that equipment covers and guards are in place; that access to exposed conductors is limited to electrically qualified personnel; and overcurrent protective devices are operable and of appropriate interrupting rating. Even the safest procedures, when performed on poorly constructed or maintained equipment represent a risk to employees.

NFPA 70E-2004 Standard Requirements [1]

Flash Hazard Analysis

• The Shock Hazard Analysis must establish the: 1. Limited Approach Boundary 2. Restricted Approach Boundary 3. Prohibited Approach Boundary • This applies to all exposed live parts operating at 50 volts or more

A large number of all serious electrical injures are related to electrical arcs created during short circuits and switching procedures. In recognition of this, standards organizations such as the National Fire Protection Association (NFPA) have provided the industry with better techniques to evaluate both the magnitude of the electrical arc hazard and appropriate protective clothing and equipment.

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Arc Flash Safety Handbook — Volume 1

Human errors and equipment malfunctions contribute to the initiation of an electrical arc. Engineering design and construction of arc resistant equipment as well as requirements for safe work practices are continuing to target the risk of electrical arc flash hazards. An electrical arc is basically an electrical current passing through ionized air. This current flow releases a tremendous amount of energy as both radiated light and convected heat. The amount of liberated energy is obviously dependent upon the system configuration, but the principle factors used in the determination of the hazard to personnel are as follows: 1. 2. 3. 4. 5.

Available short circuit current at the arc location Duration of the electrical arc Distance from the arc to personnel The arc gap Environmental conditions and surroundings at the arc location

To accurately assess the arc hazard, and make appropriate decisions regarding personal protective clothing and equipment, it is necessary to fully understand the operation of the system under fault conditions. This requires both a short circuit analysis, in all likelihood down to the panel board level, and a protective devices coordination study. It is a common misconception that arc hazards are an effect of only high voltage. The actual arc hazard is based on available energy, not available voltage. In certain conditions, a low voltage arc’s duration is longer than a high voltage arc. With this information available, the magnitude of the arc hazard at each work location can be assessed using several techniques. These techniques include:

Worker wearing an FR Rated Flash Suit

National Electrical Code 2005 Flash Protection Requirements The 2005 NEC Section 110.16 states, “Switchboards, panel-boards, industrial control panels, and motor control centers that are in other than dwelling occupancies and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field-marked to warn qualified persons of potential electrical arc flash hazards. The marking shall be clearly visible to qualified persons before examination, adjustment, servicing or maintenance of the equipment.”

• NFPA 70E, Standard for Electrical Safety in the Workplace, 2004 Edition • IEEE Std. 1584-2002, IEEE Standard for Performing Arc Flash Hazard Calculations

Each of these techniques requires an understanding of anticipated fault conditions, and the limitation of the calculation method, both of which are beyond the scope of this paper. The results of the arc flash hazard analysis are most useful when they are expressed in terms of the incident energy received by exposed personnel. Incident energy is commonly 2 2 expressed in terms of calories per cm (cal/ cm ). Arc flash protective clothing is rated in terms of its Average Thermal Performance Value (ATPV), also expressed in terms of 2 cal/cm . In addition to flame-resistant (FR) clothing and PPE, there are some safe work practices that can be adopted to minimize or eliminate the hazards. These practices include lockout/tagout along with temporary grounding, body positioning, clothing, insulated tools, and other factors that must be carefully scrutinized to insure that the risk to employees is minimized. The first choice should be to minimize or eliminate the hazard; however, when this is not possible FR rated clothing and PPE must be utilized.

Recommended Warning Label

As with the electrical shock hazard, the easiest and most effective way to mitigate the arc hazard is to completely deenergize the system for any type of maintenance activity.

Blast Hazard Analysis An electrical blast, or explosion, as it is often termed, is the result of the heating effects of electrical current and the ensuing arc. This phenomenon occurs in nature as the thunder that accompanies lightning, a natural form of an electrical arc.

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Arc Flash Safety Handbook — Volume 1 During an electrical arc, both the conducting material and the surrounding air are heated to extremely high temperatures. The resulting expansion of the air and vaporized conductive material creates a concussive wave surrounding the arc. The pressures in this wave may reach several hun2 dred lbs./ft , destroying equipment enclosures and throwing debris great distances. The pressure created during an electrical explosion is directly proportional to the available short circuit at the arc location. With a current short circuit study available, the anticipated blast pressure can be estimated from tables or charts. [7] Unfortunately, little can be done to mitigate the blast hazard, at least in terms of personal protective clothing or equipment. Blast pressure calculations can be used to determine whether enclosures will withstand an internal fault if sufficient manufacturer’s data is available. Again, it may be more important to merely recognize the magnitude of the hazard so that appropriate safety practices, such as correct body positioning, can be incorporated into work procedures. If the blast hazard is high, or if it is in a limited space, the blast can severely injure or kill a person. If these conditions are present, serious consideration should be given to not allowing personnel in the area during specific equipment operations.

Selection of Electrical Protective Equipment Most employers, operators, and electricians are knowledgeable in the selection and inspection requirements for electrical PPE used for the prevention of electrical shock hazards, as well as head, eye, hand, and foot protective equipment. All of these requirements are readily found in OSHA 1910, Subpart I, Personal Protective Equipment. OSHA 1910.137, Electrical Protective Equipment, provides the requirements for the in-service care and use of electrical protective equipment. Unfortunately, most have limited knowledge or experience with regard to arc and blast hazards that may be associated with the maintenance and operation of energized electrical equipment and the necessary protective clothing and PPE that is required. The OSHA requirements for the hazard analysis and selection of protective clothing must first be defined. OSHA 1910.132, General Requirements for Personal Protective Equipment, paragraph (d) states “The employer shall assess the workplace to determine if hazards are present, or are likely to be present, which necessitates the use of Personal Protective Equipment (PPE). If such hazards are present, or likely to be present, the employer shall: “Select, and have each employee use, the type of PPE that will protect the affected employee from the hazards identified in the hazard assessment.” OSHA 1910.132 (f ) – Training (1) states: The employer shall provide training to each employee who is required by this section to use PPE. Each such employee shall be trained to know at least the following:

• • • • •

When PPE is necessary; What PPE is necessary; How to properly don, doff, adjust, and wear PPE; The limitations of the PPE; and The proper care, maintenance, useful life, and disposal of PPE.”

Included in this hazard assessment should be the three electrical hazards; shock, arc, and blast. OSHA 1910.137 identifies the selection, inspection, and use requirements for electrical PPE. OSHA does not identify specific clothing that should be worn to protect the employee from the arc flash hazards but OSHA does specify what type of clothing is prohibited. 1910.269(l)(6)(ii) requires that “The employer shall train each employee who is exposed to the hazards of flames or electric arcs in the hazards involved.” Additionally, 1910.269(l)(6)(iii) states “The employer shall ensure that each employee who is exposed to the hazards of flames or electric arcs does not wear clothing that, when exposed to flames or electric arcs, could increase the extent of injury that would be sustained by the employee.” “Note: Clothing made from the following types of fabrics, either alone or in blends, is prohibited by this paragraph, unless the employer can demonstrate that the fabric has been treated to withstand the conditions that may be encountered or that the clothing is worn in such a manner as to eliminate the hazard involved: acetate, nylon, polyester, rayon.” OSHA does, however, require protection from the hazards of electricity in 1910.335(a)(2)(ii) which states: “Protective shields, protective barriers, or insulating materials shall be used to protect each employee from shock, burns, or other electrically related injuries while that employee is working near exposed energized parts which might be accidentally contacted or where dangerous electric heating or arcing might occur.” If, during the operation, insertion, or removal of a circuit breaker, a fault occurs, the worker may be exposed to an electric arc with temperatures up to 35,000ºF as well as high levels of incident energy. Unprotected workers exposed to an increase in skin temperature of 203ºF for 0.1 second 2 or 1.2 cal/cm of energy may suffer second or third degree burns and ignition of clothing. Protective clothing, including a complete multi-layered flash suit with hood and face shield, may be required for these activities. The consensus standard for determining the necessary clothing and training is NFPA 70E-2004, “Standard for Electrical Safety in the Workplace.” In order to properly select rated clothing and PPE to provide this protection, the employer has but two options. The employer must calculate 2 the incident energy (in cal/cm ) available at the work site, and the protective clothing required for the specific task, or as an alternative, use NFPA 70E Table 130.7(C)(9)(a) “Hazard/Risk Category Classifications” to identify the clothing required for the hazards associated with the specific task the employee is to accomplish. Caution must be used

46 if applying Table 130.7(C)(9)(a) because the short circuit current and protective device clearing time must be known per the notes at the end of the table. Note: The employer must also determine a “Flash Protection Boundary” in accordance with paragraph 130.3(A) for all energized work. At this boundary, exposed flesh must not receive a second-degree burn or worse. Once it has been determined that protective clothing is necessary to perform the specific task, the necessary protective clothing must be purchased and the employees trained to wear it properly.

Summary In resolving the issues of analyzing electrical hazards in an industry, we must follow a path that will lead to a comprehensive analysis of the problems that exist and provide a quantified value to ensure the selection of appropriate personal protection. An analysis of all three hazards, shock, arc, and blast must be completed and steps taken to prevent injuries. The following steps could be taken to ensure adequacy of the electrical safe work practices program and training of “qualified” electrical personnel: 1. Conduct a comprehensive Job Task Analysis. 2. Complete a Task Hazard Assessment including: a. Shock hazard. b. Arc flash hazard (using current Short Circuit and Coordination Studies). c. Blast hazard. d. Other hazards (Slip, fall, struck-by, environmental, etc.). 3. Analyze task for the Personal Protective Equipment needed. 4. Conduct Training Needs Assessment for Qualified and non-qualified electrical workers. 5. Revise, update or publish a complete “Electrical Safe Work Practices Program.” Regulatory agencies and standards organizations have long recognized the need to analyze the hazards of electrical work and plan accordingly to mitigate the hazards. Unfortunately, many in the electrical industry have chosen to “take their chances”, largely because nothing bad has yet to happen. As more information becomes available on the economic and human costs of electrical accidents, it is hoped that more in the industry will recognize the need for a systematic hazard analysis, and an electrical safe work program that emphasizes hazard identification and abatement.

Arc Flash Safety Handbook — Volume 1 References [1] NFPA 70E-2004, Standard for Electrical Safety in the Workplace [2] OSHA 29 CFR 1910, Electrical Standards, Federal Register Vol. 46, No. 11, Friday, January 16, 1981, Supplementary Information, I. Background, (3) Nature of Electrical Accidents, (a) Basic Contributory Factors. [3] OSHA 29 CFR 1910.331-.335, Electrical SafetyRelated Work Practices, August 6, 1990 [4] OSHA 29 CFR 1910.147, Control of Hazardous Energy Source (Lockout/Tagout), September 1, 1989 [5] OSHA 29 CFR 1910.269, Electric Power Generation, Transmission, and Distribution, January 31, 1994 [6] OSHA Instruction STD 1-16.7, Directorate of Compliance Programs, July 1, 1991 [7] Ralph H. Lee, “Pressures Developed by Arcs”, IEEE Transactions on Industry Applications, Vol. IA-23, No. 4, p. 760, July/Aug. 1987. Dennis K. Neitzel, C.P.E., Director of AVO Training Institute, Inc., Dallas, Texas, has over 37 years experience in Electrical Utility and Industrial facilities electrical systems. He is an active member of IEEE, ASSE, NFPA, AFE, and IAEI. He is a Certified Plant Engineer (C.P.E.) and a Certified Electrical Inspector-General. Mr. Neitzel earned his Bachelor’s degree in Electrical Engineering Management and his Master’s degree in Electrical Engineering Applied Sciences. He is also a Principal Committee Member for the NFPA 70E, Standard for Electrical Safety in the Workplace; serves as the Working Group Chairman for revising IEEE Std. 902 (The Yellow Book), IEEE Guide for Maintenance, Operation, and Safety of Industrial and Commercial Power Systems; is co-author of the Electrical Safety Handbook, 2nd Edition, McGraw-Hill Publisher; and serves as the ASSE Engineering Practice Specialty’s ByDesign Newsletter Editor. Mr. Neitzel received the Engineering Practice Specialty “Safety Professional of the Year” award for 2003-2004 from the American Society of Safety Engineers.

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Electrical PPE Trends NETA World, Fall 2005 Issue by Bill Rieth Salisbury

NFPA 70E is raising the level of awareness for electrical safety in the workplace. PPE (personal protective equipment) is an important element to working safely. More and more companies are developing electrical safety programs and providing better training for employees who work on or near exposed energized electrical equipment. Virtually unused as little as 5 or 6 years ago, lockout/tagout (LOTO) programs are now common in the workplace. Like many safety procedures that are implemented, LOTO programs were not met with open arms when they were first introduced. Concerns included time delays, cost of equipment, and cost of additional training. However, it quickly became evident that the cost saving benefits of reducing injury far outweighed any other perceived costs that may have existed. As a result, today’s electrician or maintenance person would not think of working on a piece of equipment that was not locked-out or tagged-out. Along with the advancements of electrical safety awareness, there have been advancements of electrical PPE. One of the most difficult aspects of implementing a successful electrical safety program is to ensure the worker is actually using the PPE in the field. One of the best ways to accomplish this is to make the necessary PPE as unintrusive as possible. The less the required PPE hinders a worker, the more likely the worker is to wear it. With this in mind, many manufacturers have made an effort to provide lighter weight clothing, lighter tinted face shields, and thinner voltage rated rubber goods to allow for easier use of these products by the worker. Arc-flash clothing has become much more comfortable to wear in the last few years. Flame resistant fabrics that are rich in cotton content are better moisture movement vehicles than synthetic FR fabric alternatives. FR cotton blends allow a person’s body to radiate itself correctly by allowing the passage of air through the fabric. The human body cools itself by perspiring, but it is not the perspiration on the skin that does the cooling. It is the evaporation of perspiration that cools the body down.

This evaporation occurs when air is introduced to the skin. One more advancement in FR fabrics is the performance of physically lighter FR cotton and cotton blends in higher cal/cm² exposures. For instance, a 7 oz FR cotton blend fabric has an 8.2 cal/cm² rating yet feels much like a normal work shirt or pant. These garments are put through a rigorous laundering test to ensure that they maintain their FR properties through repeated washings. Regular proper laundering of the garment ensures that there are no contaminants which may add to the flammability of the garment and also improves the probability that it will be worn by the worker.

Arc flash face shields have undergone dramatic changes. ASTM F2178-02 is the standard used to test arc flash face shields and includes very specific requirements. The shield must not only dissipate heat, it must also protect the eyes

48 from the bright light emitted during an arc flash. Just 18 months ago the highest rated hard hat mounted face shield had a rating of 10cal/cm². The tinting of the shield at that time was dark and made identifying certain wire colors difficult. Today some manufacturers provide face shields offering 15 cal/cm² protection level while providing a much clearer lens. Light transmission is the key term when discussing clarity of a face shield. The higher percentage of the light transmission rating will improve color recognition of wires. Normal safety sunglasses have a light transmission rating of less than 20 percent while a clear shield typically has a light transmission rating of 85 percent. Proper cover-up for equipment is also an area of concern for companies today. It is common to be working on a properly de-energized and locked-out tagged-out piece of electrical equipment but still be positioned in close proximity of energized equipment. Most incidents involving electrical contact are due to accidental or incidental contact or what is more commonly called brush contact. There are rubber insulating materials in the market specifically designed to ensure that this type of contact does not occur. One variation of this material, known as roll blanket material, comes in two different types and is available in three levels of voltage protection, Class 00 (max 500 V), Class 0 (max 1000 V), and Class 1 (max 7,500 V).

The second type is a clear PVC material with a Class 1 rating. Both of these materials are designed to be cut to size for the application and are extremely flexible and easy to install. The use of insulating material will reduce the opportunity of an arc flash incident and reduce shock potential. Many people in the industry still view voltage gloves as cumbersome and difficult to use. These people envision the typical lineman’s glove, such as a Class 2 glove which is rated for up to 17 kV work, as the glove they would need to use in lower voltage tasks. Because of this perception, many people decide not to use voltage gloves at all. Not only are these people exposed to unnecessary risk of injury, they are not complying with the law which requires voltage gloves to be used when working on or near 50 volts or more. Voltage gloves are now available in Classes 00 and Class 0.

Arc Flash Safety Handbook — Volume 1 These low voltage gloves are perfect for today’s commercial and industrial applications. Due to the thinness of these classes of gloves, they are much easier to work in. They offer great feel and dexterity allowing the workers to perform tasks with little difficulty while allowing them to work safely. These gloves comply with ASTM Standard D120. The gloves should be dielectrically retested every six months from the date of issue for service. Gloves not issued for service shall not be placed into service unless they have been electrically tested within the previous twelve months per ASTM F496 and OSHA CFR 29 1910.269. There are independent glove testing laboratories throughout the country that can perform this service. Another option that is catching on in the industry is what is being called an alternating color program. In this program the decision is made to use two different colors of gloves. Class 0 and 00 TYPE I nonozone resistant natural rubber gloves come in various colors . Class 0 and 00 gloves are also available in EPDM (TYPE II) rubber in blue color. As an example, a company could decide to use red gloves for six months. At the end of six months the red gloves would be taken out of service or sent out for retesting. The workers would then be issued black gloves for the next six months. This program ensures not only that the electrically tested gloves are up to standard, but it also allows easy visual verification that the worker is using electrically-tested gloves. The use of leather protectors that comply with ASTM F696 should be used with all rubber insulating gloves. It is extremely important to remember that voltage rated gloves are the only electrical safety items designed for intentional contact with an energized piece of equipment; therefore, it is extremely important to both air test and visually inspect rubber gloves prior to each use. Everyday tools used for maintenance have been made into PPE items. Insulated tools that are manufactured to the ASTM F1505 standard and rated for maximum voltage of 1000 Vac will provide workers with additional protection. The 2004 edition of NFPA hazard risk category table 130.7 (C)(9)(a) requires insulated tools for certain tasks. The electrical hazard and the level of the hazard must be identified prior to selecting your PPE. The 2004 edition of NFPA 70E standard makes it easier than ever to develop and implement an electrical safety program. By following the requirements for electrical PPE outlined in NFPA 70E, along with the advancements in today’s electrical PPE, companies can ensure workers are performing daily tasks safely. Bill Rieth, Regional Manager/Trainer for Salisbury. Bill is a leading industry trainer of arc flash safety. He was instrumental in developing Salisbury’s PPE program for the electrical industry on arc flash protection. He is a member of NFPA, IEEE, and participates in training for NJATC. He has extensive knowledge of NFPA 70E and OSHA in regard to electrical safety including the issue of arc flash safety and the proper selection of PPE.

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Proper PPE — A Journey with No End: One Company’s Experiences NETA World, Fall 2005 Issue by Tony Demaria Tony Demaria Electric, Inc.

Forty-two years ago, when starting my apprenticeship in an IBEW shop in the Los Angeles area, there was no PPE at the shop. One exception was a very old, heavily scratched face shield. It was sometimes found in the vicinity of the grinding wheel. When the grinding produced a large enough quantity of sparks to prevent work from being done, the shield was used. For small delicate work, the face shield was left where it lay, as it could not be seen through. In four years of working in that shop, there were no safety meetings and no formal safety training. As I recall, no safety training was offered at Los Angeles Trade Technical College where the apprenticeship classes were held. Safety was taught “on the job,“ where one of the senior journeyman explained how to tell the difference between 120 and 480 volts. This was performed using two fingers of one hand only. We were reminded of the importance of not using fingers of different hands as this could lead to a bad consequence, such as death. The difference in voltages could be distinguished by the tingling in your hand. The more tingling you felt, the higher the voltage. For those readers not up to date on recent advances in safety, this method is no longer acceptable. Going to work for the Los Angles Department of Water and Power produced structured safety training. There were monthly safety meetings. The majority of the work was medium and high voltage with the associated higher risks. One training topic was resuscitation. It was not called CPR at the time. This proved valuable as within a short time I was provided an opportunity to assist a child using the rescue breathing technique recently taught. The results of both job experiences, however, appeared to be approximately the same at work. There was an endless stream of cuts, bruises, and strains. Broken bones and fatalities were part of the mix. One hydroelectric construction

project I worked on had one fatality a year for three years with no change in safety practices or management concerns. This was all accepted without question as part of working in a dangerous environment. In the 70’s we began to hear this dreaded word — OSHA. These guys were going to screw up everything. How could one possibly perform a job with a lot of rules to confuse everybody? Even worse, wearing a bunch of stuff like safety belts and gloves for easy tasks would only slow down the work. Two incidents that occurred very close to me changed my attitude. One involved a coworker falling from approximately 20 feet onto some protruding steel. He almost bled to death in my arms. Only luck and a close hospital saved his life. In the other incident, the electrician was not as fortunate and it ended in a fatality. When starting an electrical contracting business 30 years ago, safety was not the first thing on my mind. Getting the job done and making money were the priorities. This soon changed as the enormity of the situation became apparent. I faced a huge responsibility for the safety of the electricians performing the work. What could I do to ensure that all personnel went home every night with all body parts working correctly, and, most importantly, alive! Working safe involves several elements — PPE is only one. The first step is always to insure the safest working environment possible. If the equipment being worked on is energized, the first choice is to turn it off. If the floor is slippery with oil, the number one thought should be to clean the floor, not “be careful of your surroundings.” This short article is not an overview of safety. The focus is PPE and how far we have come in a few short years. Most importantly, what can we do now? The two incidents I referred to above would never have happened had better safe practices been in place. However, had PPE been

50 utilized (a safety harness and voltage-rated gloves) when bad things happened and mistakes made, no one would have been hurt. Here lies one danger of PPE. It has been and can be used as the first line of safety. Do not fall into this trap. Another danger of PPE is once it is put on, the electrician may get a feeling of invulnerability. Wearing all this gear, you can feel like Superman. You are not stronger and may even have reduced awareness such as limited vision with a flash hood on. This is a complex subject and sometimes offers confusing options as to what is the best choice.

Meeting the Challenge of PPE Safety 1. How can employers and employees understand and conform to the frequently changing laws, standards, regulations and customer rules on PPE? • Attend conferences, especially the IEEE PCIC/IAS Electrical Safety Workshop that has many sessions specifically on PPE. • Read a book! There are currently several excellent new safety books listing appropriate PPE. Check the NFPA and IEEE on-line bookstores. • Go to special safety training schools. Offers frequently come in the mail and can be found on-line. Schools vary from one day to two weeks. • Hire a consultant who is knowledgeable on PPE. An expert from outside the company may offer unique expertise and insights. 2. Exactly what PPE should be purchased with a limited budget to get the best product available at that time? • Talk with the manufacturers of PPE and invite them to your shop to demonstrate their equipment. This is free and carries no obligation. • Purchase several different types and distribute them to employees to test, evaluate, and report back their findings. • Call other companies using similar PPE and ask their opinion. A network of like-minded organizations can provide valuable information. 3. How does a company involve all field personnel in the creation and implementation of the policies on PPE? • At your weekly safety meeting, allow specific time to review what PPE is being used and feedback as to what worked best or what problems were encountered. • Form a specific safety committee to examine one product item, such as arc flash protection, and allow them time for a thorough evaluation. • Rotate committees frequently to make sure all field personnel have the opportunity to participate.

Arc Flash Safety Handbook — Volume 1 The responsibility of every company is to insure that the best PPE currently manufactured is available to its field personnel. However, it does not end here. The problem is making sure the PPE is used! Involving all employees in the process is the best way to succeed in meeting this challenge. The experiences at our company have not always been positive. There have been hurt feelings, angry words, and wasted money on bad equipment. Management gets frustrated when PPE is underutilized, and everyone gets overwhelmed by all the unending changes. But here is the good news. The workers compensation modification rate earned by our company is the lowest possible, saving tens of thousands of dollars per year. Why? Because we work much safer than in earlier years. Accidents have decreased radically. The best news is deeper. We do not wear PPE to save money on insurance or because some rule says we must. PPE is bought, cared for, and worn because it is the right thing to do. We really care and look out for each other. A new culture is building that tells us safety is a moral decision. It’s a good way to go to work. All this is a never-ending, on-going process to be repeated over and over. Remember, having and using the proper PPE is a journey, not a destination! Tony Demaria served an IBEW Apprenticeship starting in 1963 and then worked for Los Angeles Department of Water and Power in substation maintenance for eight years. He has owned and operated Tony Demaria Electric for over 25 years, specializing in maintenance and testing switchgear and large motors for industrial facilities. Tony Demaria Electric is a NETA Accredited Company, and Tony serves on the NETA Safety Committee.

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Empowering Safety Part I — From Gloves to Arc Flash Suits Employers Must Provide, Maintain and Ensure the Proper Use of their Employees’ PPE (See page 58 for Part Two)

NETA World, Fall 2005 Issue by Charlie Simpson Burlington Electrical Testing Co.

The Occupational Safety and Health Administration (OSHA) (www.osha.gov) states that employees who perform work involving electric power generation or distribution are exposed to “a variety of significant hazards, such as fall, electric shock, and burn hazards, that can and do cause serious injury and death.” In fact, OSHA calculates that an average of 444 serious injuries and 74 fatalities occur annually among these workers. In just about every type of industrial work setting, more and more workers are using personal protective equipment (PPE) to help protect them from injury and even death. If any industry exemplifies the need for continued safety practices, it is the electric power generation, transmission, and distribution industry. From performing infrared scans to complete shutdown repair, employee safety is more critical than ever. Federal and state agencies are letting offenders know this fact through steep fines levied against employers.

Responsibility: Where to Start Ideally speaking we are all responsible for safe work habits and environments. Realistically, with tight deadlines and budgets, employees may not always opt for the safest versus the more efficient method of performing an operation. OSHA, however, makes it clear that employers are ultimately responsible for the safety of their employees, including providing the proper PPE. Of course this does not mean employees are not culpable for their actions or inactions, but all infractions should be acted on and documented by the employer. For live electrical work, there are no gray areas. OSHA requires nothing less than compliance when it comes to employee safety. Where a specific article may not apply, OSHA’s general duty clause covers it all. The general duty

clause is defined in the Occupational and Safety Health Act of 1970 – Section 5 (a) and states “Each employer (1) shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees; (2) shall comply with occupational safety and health standards promulgated under this Act.” A good place for employers to start protecting their employees is with an in-house safety guide or policy manual. Written by your company safety officer, the manual may be reviewed by both employees and management to determine areas for improvement and then reviewed annually or as needed to incorporate regulatory changes or technology advancements. A safety manual should define the safety director’s responsibilities, the supervisor’s responsibilities, the employees’ responsibilities, as well as any subcontractor’s responsibilities to ensure safe work practices. Other areas that one may want to consider when outlining a safety guide are forming and maintaining a safety committee, scheduling safety training, equipment and facility inspection checklists, accident reporting procedures and investigation forms, emergency response guidelines, and best practices for using and maintaining PPE. Per OSHA 1910.335(a)(1)(i) Safeguards for Personnel Protection. An employer is responsible for providing employees with all appropriate work-related PPE. Employers must insure that employees are correctly trained in the use and maintenance of the PPE and that employees are actually wearing the PPE on the job sites. Training can be provided by local universities or colleges; by county, state, and federal government agencies such as OSHA; by union academies; and by various independent training companies and PPE providers, either on your site or at a trainer’s facilities. Keeping records of all training levels,

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courses taken, and certifications achieved by all employees in a single location will ease reference. Additional education should include training in first aid and CPR through a certified organization such as the American Red Cross.

New Laws Coming? On June 15, 2005, OSHA listed several proposed rule changes to its PPE guidelines, due to the fact that the existing standard for the construction of electric power transmission and distribution equipment (contained in Subpart V of OSHA’s construction standards (29 CFR part 1926) was promulgated in 1972, over 30 years ago. According to OSHA Federal Register Docket No. S-215, “Employees maintaining or constructing electric power transmission or distribution installations are not adequately protected by current OSHA standards, though these employees face far greater electrical hazards than those faced by other workers. The voltages involved are generally much higher than voltages encountered in other types of work, and a large part of electric power transmission and distribution work exposes employees to energized parts of the power system.”

NIOSH Conclusions Conclusions, seemingly obvious, found in NIOSH reports have stated that employers need to: • Have a standard operating procedure (SOP) that states that all high voltage work is performed by qualified persons.

• Have a proper ground in place for all electrical transformers and equipment. • Have an SOP that addresses the procedures for a lockout/tagout system.

• Have all power panels and transformers labeled so that it is evident where electricity is provided and from which panels. • Train employees in the proper use of personal protective equipment (PPE).

• Have an SOP that addresses environmental conditions (rain, snow, lightning, etc.) during certain types of work activities, such as high voltage electrical work.

• Have an SOP stating that there is an employee located within a short distance of any employee working with high voltage equipment in case of an emergency.

The document further states that “Some of the technology involved in electric power transmission and distribution work has changed since then, and the current standard does not reflect those changes.” For example, the method of determining minimum approach distances has become more exact since 1972, and the minimum approach distances given in existing Sec. 1926.950(c)(1) are not based on the latest methodology. Also according to the proposed changes, “Interpreting existing Sec. 1910.136(a) so as to recognize electrical hazard footwear as a primary form of electrical protection could expose employees to electric shock hazards if they believe that the real primary form of electrical protection (for example, rubber insulating gloves or blankets) is no longer necessary. This is true for several reasons. First, electrical hazard footwear only insulates an employee’s feet from ground. The employee can still be grounded through other parts of his or her body. Second, the insulation provided by electrical hazard footwear is good only under dry conditions. This footwear provides little if any protection once it becomes wet or damp. Lastly, the voltage rating on electrical hazard footwear is only 600 volts.” The proposal maintains that because of these limitations, electrical hazard footwear “should not be addressed by Sec. 1910.136, which is designed to provide protection to employees’ feet. The need for conductive footwear, whether or not it provides protection for the foot, is adequately addressed by the general requirement in Sec. 1910.132(a) to provide personal protection equipment. Therefore it is proposed to delete language relating to electrical hazards from Sec. 1910.136(a).” Hearings on these changes are scheduled to be held December 2005 in Washington, DC.

Protecting Against Arc Flash The electric power distribution industry has been addressing safety, including shock, burns and blast, in stages for more than 30 years. The area of rising concern is for arc flash protection. From insulated gloves and safety goggles, to fire resistant clothing and arc flash suits, PPE is helping reduce injuries and fatalities. However, PPE is only effective when used, and used properly. Not surprisingly, the major driving force behind this safety initiative is NFPA 70E 2004. Published by the National Fire Protection Association (www.nfpa.org), NFPA 70E 2004 Edition is a voluntary standard for electrical safety in the workplace. Per the foreword, NFPA 70E was created because “… a need existed for a new standard tailored to fit OSHA’s responsibilities, that would be fully consistent with the National Electrical Code (NEC).” This standard creates thresholds for worker protective apparel based on exposure to arc hazard risk and is designed to protect workers that install, maintain, or repair electrical systems. Although NFPA 70E is not a law, companies are expected to maintain a safe place of employment for their workers, including appropriate protection from electric arc flash. OSHA 1910.335(a)(1)(i) states, “Employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment

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Arc Flash Safety Handbook — Volume 1 that is appropriate for the specific parts of the body to be protected and for the work to be performed.” But before one can determine the proper arc flash protection, an arc flash and shock hazard analysis must be performed. An arc flash hazard analysis is the first step toward determining the proper PPE, along with the arc flash boundaries. This analysis can then be an integral part of an employer’s overall electrical safety program. An arc flash hazard analysis will allow calculation of the incident energy, which is the energy from an arc flash per unit area on a surface located at some distance away from the flash location. The working distance is the distance from where the worker stands to the flash location. IEEE Std 1584 uses 18 inches for everything except low-voltage power circuit breakers, which have a cabinet depth of about 24 inches. IEEE Std1584 also uses 36 inches for voltages above 600 V to its 15 kV limit. It is the incident energy generated during an arc flash that causes burns to the skin. 2 The typical unit of incident energy is the cal/cm . Although there are various methods of calculating values of available heat energy from an electric circuit, OSHA “will not endorse any of these specific methods.” Each method requires parameters, such as fault current, the expected length of the electric arc, the distance from the arc to the employee, and the clearing time for the fault – that is, the time the circuit protective devices take to open the circuit and clear the fault. It should be noted that both the NFPA 70E and IEEE Std 1584 use the assumption that an arc flash generating 2 2 2 1.2 calorie/cm (1.2 calorie/cm = 5.02 joules/cm = 5.02 2 watt-sec/cm ) for 0.1 second will result in the onset of a second-degree burn. It is assumed that a second-degree burn will be curable and will not result in death. A first degree burn is the equivalent of a sun burn; second degree burns will blister, but the skin will heal; third degree burns result in permanent damage and scarring of the skin and internal tissue.

PPE Technologies The technology that comprises PPE continues to evolve in the electrical industry. Today the range of PPE can include primary and secondary insulation products, as well as additional equipment such as:

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Rubber Gloves (with Leather Protectors) Rubber Sleeves Fire Resistant Everyday Work Wear Hot Sticks Insulated Hand Tools Blast Blankets Portable Grounds Rubber Matting Arc Flash Suits Lockout / Tagout Systems

Primary insulation, such as rubber gloves and rubber blankets normally insulate an employee directly from an energized part. Secondary insulation such as footwear and matting normally insulates an employee’s feet from a grounded surface (See New Laws Coming for changes in footwear classifications). Each employee should inspect his or her own PPE at the beginning of each work period and again before each use, while the company safety officer should establish a periodic review of all PPE. Part 2 of Empowering Safety in the Winter issue of NETA World provides PPE purchasing tips including glove and fire resistant clothing ratings as well as suggestions on how to help ensure employees wear the appropriate PPE. Charlie Simpson is the Technical Writer for Burlington Electrical Testing Co. (BET, www.betest.com, Croydon, PA). BET, a NETA Accredited Company, is an independent electrical testing and maintenance company servicing the industrial, commercial, construction, medical and utility industries for all manufacturers of power generation and distribution equipment in the low to EH voltages.

Acknowledgements BET appreciates the contributions of Peter Senin, president of Burlington Safety Labs and Kevin McLaughlin of Tyndale who contributed their expertise to this article, and thanks Jim White of Shermco for reviewing the accuracy of this article. Photo courtesy of Burlington Safety Laboratory, Inc.

Figure 1 — Rubber gloves, one of the most prevalent pieces of PPE are manufactured to at least twice the mandated thickness providing the first line of defense for electrical power distribution workers

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Do I Have to Comply with NFPA 70E? NETA World, Fall 2005 Issue by Lynn Hamrick ESCO Energy Services Company

Much information and guidance is being provided, from a variety of sources, with respect to NFPA 70E compliance. This narrative provides background information on the evolution of NFPA 70E and the current regulatory activities associated with this standard. Additionally, it simplifies and condenses the available information into viable recommendations for implementing applicable requirements.

Does OSHA Require compliance to NFPA 70E-2004? When discussing NFPA 70E with personnel at industrial facilities, one of the first questions they ask is, “Does OSHA require compliance to this standard?” In answering this question, one must first consider some background information associated with existing OSHA standards and this particular standard. Following the Occupational Health and Safety Act of 1970, OSHA adopted the 1968, and then the 1971, edition of NFPA 70, National Electric Code, under Section 6(a) of the Act. Subsequent changes or additions to the OSHA requirements would require performing the process outlined in Section 6(b) of the Act, which requires a public notice or an opportunity for public comment and public hearings. This is an expensive and lengthy process at best. Unfortunately, OSHA found that the NEC was lacking in many aspects of electrical safety. The NEC primarily deals with the design and construction of electrical installations. However, OSHA’s responsibilities include the employers and employees in the workplace, and the NEC does not address the requirements for electrical safety-related work practices associated with the operation and maintenance of electrical systems. Realizing this difference, the National Fire Protection Association (NFPA) offered its assistance in preparing a document “to assist OSHA in preparing electrical safety standards that would serve OSHA’s needs and that could be expeditiously promulgated through the provisions

of Section 6(b) of the Occupational Safety and Health Act.” The resulting Standard for Electrical Safety Requirements for Employee Workplaces, NFPA 70E, was first issued in 1979 with the specific purpose of being a companion document to the NEC. Subsequent to the initial versions of NFPA 70E, OSHA standard 29CFR1910.331-335, commonly referred to as Subpart S — Electrical Standards, was issued in 1990. This standard deals with requirements associated with electrical safety-related work practices for industrial facilities. In general, this OSHA standard only addresses the electrical shock hazard and does not specifically address electrical arc flash or arc blast hazards. It includes a description of the application of the standard (Section 1910.331), employee training requirements (Section 1910.332), safety-related work practices (Section 1910.333), limitations in the use of equipment (Section 1910.334), and required personnel protection safeguards (Section 1910.335). This standard delineates requirements for qualified persons which include being familiar with the standard as well as being trained and familiar with the work being performed. It also requires appropriate safety signage to warn employees of electrical hazards and states that “employees working in areas where there are potential electrical hazards shall be provided with, and shall use, electrical protective equipment that is appropriate for the specific parts of the body to be protected and for the work to be performed.” Unfortunately, it does not specifically define what the appropriate electrical protective equipment is for the potential electrical hazard. However, this requirement does imply that the magnitude of the electrical hazard should be known and that the protective equipment should be selected accordingly. In an effort to further define the requirements for electrical safety, the fifth edition of NFPA 70E was published in 1995. This standard introduced the concept of limits of approach, and the establishment of a flash protection boundary was introduced. In the sixth edition, published in 2000,

Arc Flash Safety Handbook — Volume 1 further focus on flash protection and the use of personal protective equipment (PPE) was expanded with charts being added to assist the user in applying PPE for common tasks. With the most recent seventh edition, published in 2004, the standard was rearranged to be consistent with the NEC and was renamed Standard for Electrical Safety in the Workplace. Another OSHA requirement, NFPA 70, the National Electric Code, further amplifies these requirements in its 2002 edition. It defines a qualified person as, “One who has skills and knowledge related to the construction and operations of the electrical equipment and installations and has received safety training on the hazards involved.” NEC - 2002 also provides specific language associated with arc flash hazards: “Section 110.16 Flash Protection. Switchboards, panelboards, industrial control panels, and motor control centers in other than dwelling occupancies, that are likely to require examination, adjustment, servicing, or maintenance while energized, shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment. FPN No. 1: NFPA 70E-2000, Electrical Safety Requirements for Employee Workplaces, provides assistance in determining severity of potential exposure, planning safe work practices, and selecting personal protective [4] equipment.” With the 2002 edition of the NEC, arc flash protection has been introduced into the requirements. Further, NFPA 70E-2004 has been provided as a source document for determining the magnitude of the hazard and the appropriate protective measures to be taken to safeguard employees. What should be derived from the above discussion is that NFPA 70E is considered an industrial consensus standard and is intended for use by employers, employees, and OSHA. OSHA has not adopted NFPA 70E as it did earlier versions of the NEC simply because adoption would require the lengthy and expensive process outlined in Section 6(b) of the Act. OSHA has instead referenced compliance to NFPA 70E in a recent citation using Section 5(a)(1) of the Occupational Safety and Health Act of 1970, commonly referred to as the “general duty clause,” as their basis for this citation. The general duty clause states that employers “shall furnish to each of its employees employment and a place of employment which are free from recognized hazards that are causing or likely to cause death or serious physical harm to his employees.” This methodology for implementing potentially new requirements through the use of industrial consensus standards, like NFPA 70E, is common practice by OSHA. In a recent standard interpretation letter dated 7/25/03, OSHA’s Russell Swanson stated, “Industry consensus standards, such as NFPA 70E, can be used by employers as guides to

55 making the assessments and equipment selections required by the standard. Similarly, in OSHA enforcement actions, they can be used as evidence of whether the employer acted reasonably.” Further indications from OSHA’s website state that proposed changes to OSHA’s general industry electrical installation standard (1910 Subpart S) focus on safety in the design and installation of electric equipment in the workplace. The changes draw heavily from the 2000 edition of the National Fire Protection Association’s (NFPA) Electrical Safety Requirements for Employee Workplaces (NFPA 70E), and the 2002 edition of the National Electrical Code (NEC).” It is clear from the above evidence that OSHA is using NFPA 70E as an industrial consensus standard. Further, OSHA expects employers and employees to comply with the provisions of NFPA 70E regardless of whether or not it has been adopted as an OSHA requirement.

What Does NFPA 70E-2000 Compliance Mean for My Facility? The next question one has to ask is, “How will NFPA 70E compliance affect me?” NFPA 70E – 2004 and the NEC - 2002 require and/or recommend that facilities provide: • A safety program with defined responsibilities • Electrical hazards analyses • Personal protective equipment (PPE) for workers • Training for workers • Tools for safe work • Warning labels on equipment NFPA 70E further requires that safety-related work practices shall be used to safeguard employees from injury while they are working on or near exposed electric conductors or circuit parts that are or can become energized. The specific safety-related work practice shall be consistent with the nature and extent of the associated electric hazards. These work practices shall include wearing protective clothing and other personal protective equipment (PPE) when working with the flash protection boundary. With regard to arc flash hazards, a “flash hazard analysis shall be done in order to protect personnel from the possibility of being injured by an arc flash. The flash hazard analysis shall determine the Flash Protection Boundary and the personal protective equipment that people within the Flash Protection Boundary shall use.” This standard also provides some descriptions associated with working distances, or boundaries, with respect to being a qualified versus unqualified person. These boundaries are as follows: • Flash Protection Boundary — The distance at which the incident energy from the live part is equal to 1.2 cal/ cm2, the limit for a second-degree burn on bare skin. Persons must not cross this boundary unless they are

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wearing appropriate personal protective clothing and are under close supervision of a qualified person.

• Limited Approach — The distance at which barriers should be placed to protect unqualified personnel from an electrical hazard. Only qualified persons and escorted unqualified persons are allowed to enter a limited space.

• Restricted Approach — The distance at which only qualified personnel are allowed with appropriate protective clothing and personal protective equipment for the associated hazard. No unauthorized conductive material and no unqualified persons are permitted to cross a restricted boundary. Further, a documented and management-approved plan is required to enter a restricted space. • Prohibited Approach — The distance at which qualified personnel should not introduce grounded equipment or material not insulated for the voltage rating due to the possibility of flashover. A documented and management-approved risk analysis and plan are required to enter a prohibited space. A pictorial representation of these boundaries is provided in figure C.1.2.4 from NFPA 70E, reproduced below. Flash protection boundary Limited approach boundary Limited boundary/space Restricted approach boundary Any point on an exposed, energized electrical conductor or circuit part Restricted apace Prohibited approach boundary Prohibited space

To accommodate the work practices stated above for many common tasks, NFPA 70E Table 130.7(C)(9)(a) has been provided for use. However, specific fault currents and fault clearing times were assumed in the preparation of those tables. The assumed short circuit current capacities and fault clearing times are listed in the notes of the table. If the fault currents or fault clearing time are different than those used in generating the recommendations in the table, the incident energy can be very different. These tables are suitable for their intended use, providing an immediate answer, but are not a substitute for performing a more detailed arc flash hazard analysis specific to the facility. Analyses that take into consideration the true operating conditions of a specific facility can be performed using the methods outlined in either NFPA 70E or IEEE Standard 1584-2002. The

IEEE 1584-2002 guidelines have been derived as a result of extensive testing and, therefore, are typically considered to be more accurate. Use of either methodology should be considered acceptable. With regard to determining appropriate work practices and PPE, the magnitude of the potential arc flash hazard is first determined based on work being performed, the exposure to the employee, and the potential incident energy of an arc flash. The appropriate PPE is then selected with guidance provided in the PPE Matrix, NFPA 70E Table 130.7(C)(10). Further guidance on protective clothing characteristics is provided in NFPA 70E Table 130.7(C)(11). With regard to what an employer should already be doing to minimize the exposure of employees to energized circuits, the NEC has provided guidance:

“110.27 Guarding of Live Parts.

(A) Live Parts Guarded Against Accidental Contact. Except as elsewhere required or permitted by this Code, live parts of electrical equipment operating at 50 volts or more shall be guarded against accidental contact by approved enclosures or by any of the following means: 1. By location in a room, vault, or similar enclosure that is accessible only to qualified persons.

2. By suitable permanent, substantial partitions or screens arranged so that only qualified persons have access to the space within reach of the live parts. Any openings in such partitions or screens shall be sized and located so that persons are not likely to come into accidental contact with the live parts or bring conducting objects into contact with them. 3. By location on a suitable balcony, gallery, or platform elevated and arranged so as to exclude unqualified persons.

4. By elevation of 2.5 m (8 ft) or more above the floor or other working service.

(B) Prevent Physical Damage. In locations where electric equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.

(C) Warning Signs. Entrances to rooms and other guarded locations that contain exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter.”

For the employer, this requires that guards be provided for all exposed circuitry, even within commonly opened switchboards, panelboards and industrial control panels, to ensure that the risk to employees is minimized. A logical inference from the NEC requirements stated above is that the provided guards should also accommodate and safeguard employee’s exposure to an associated arc flash hazard.

Arc Flash Safety Handbook — Volume 1 In summary, OSHA expects employers and employees to comply with the provisions of NFPA 70E regardless of whether or not it has been adopted as an OSHA requirement. NFPA 70E compliance for a facility involves putting an electrical safety program in place, which will identify and analyze electrical hazards in the workplace, educate the workforce on those hazards, require the use of appropriate PPE, and implement warning labels and guards to protect the workers.

References [1] NFPA 70E, Standard for Electrical Safety in the Workplace – 2004 Edition, Forward to NFPA 70E. [2] OSHA Standard 29CFR1910,Section.335(a)(1)(i).

[3] NFPA 70, National Electric Code – 2002 Edition, Section 100, Definitions.

[4] NFPA 70, National Electric Code – 2002 Edition, Section 110.16, Flash Protection.

[5] Occupational Safety Health Act of 1970, Section 5(a)(1). [6] OSHA Standard Interpretations dated July 25, 2003, “General Duty Clause (5(a)(1)) citations on multiemployer worksites; NFPA 70E electrical safety requirements and personal protective equipment.”

[7] OSHA Trade Release dated April 2, 2004, “OSHA Proposes Revisions to Electrical Installation Standard.” [8] NFPA 70E, Standard for Electrical Safety in the Workplace – 2004 Edition, Section 110.8(A). [9] NFPA 70E, Standard for Electrical Safety in the Workplace – 2004 Edition, Section 130.3.

[10] NFPA 70E, Standard for Electrical Safety in the Workplace – 2004 Edition, Section 130.7(C)(9)(a). As Operations Manager of ESCO Energy Services Company, Lynn brings over 25 years of working knowledge in design, permitting, construction, and startup of mechanical, electrical, and instrumentation and controls projects as well as experience in the operation and maintenance of facilities. Lynn is a Professional Engineer, Certified Energy Manager and has a BS in Nuclear Engineering from the University of Tennessee.

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Arc Flash Safety Handbook — Volume 1

Empowering Safety Part 2 — From Gloves to Arc Flash Suits Employers Must Provide, Maintain and Ensure the Proper Use of their Employees’ PPE NETA World, Winter 2005-2006 Issue by Charlie Simpson Burlington Electrical Testing Co.

According to the Liberty Mutual Research Institute for Safety (www.libertymutual.com/research-institutereport2004), nearly 3.5 million workers suffered disabling injuries in the workplace in 2003, costing businesses more than $190 billion in direct and indirect costs. Employee safety is getting more attention than ever in the power distribution installation and maintenance industry. Personal Protective Equipment (PPE) helps provide the level of safety mandated by organizations such as OSHA and NFPA. Today the range of PPE can include primary and secondary insulation products, as well as equipment such as hot sticks, insulated hand tools, portable grounding cables and lockout/tagout systems. Primary insulation, such as rubber gloves and rubber blankets normally insulate an employee directly from an energized part. Secondary insulation such as footwear and matting normally insulates an employee’s feet from a grounded surface (See New Laws Coming in Part 1 of the Fall issue of NETA World.) Each employee should inspect his or her own PPE at the beginning of each work period and again before each use, while the company safety officer should establish a periodic review of all PPE. One of the oldest, most reliable forms of PPE, and probably most taken for granted, is the rubber glove. Gloves are most susceptible to daily wear and tear damage; therefore, it is mandatory that employers collect and test gloves, as well as inspect leather gloves, carrying bags, etc. Rubber gloves must be tested every six months. They may be tested and results documented in-house or sent out to be tested by an independent laboratory. OSHA also says rubber blankets and sleeves shall be tested every 12 months. Although there are currently no official standards for testing laboratories, employers can look for laboratory certification from an organization such as the Association

of North American Independent Laboratories (NAIL) for protective equipment testing, which conducts independent inspections and accreditation of testing laboratories. Even if gloves are sent out for testing, employers can still maintain a glove log using an identification system for individual gloves which includes when they are tested and to whom they were issued. Gloves should be stored out of sunlight in the approved bag, and kept clean, which includes keeping bug repellents and lotions from coming in contact with the interior or exterior of the glove. Such products can break down the integrity of the rubber. Glove testing guides and specifications can be found in OSHA 1910.137. Gloves are rated in six classes according for use at a maximum voltage. Colored labels located near the glove cuff indicate the voltage application rating such as in Table 1.



Range 00 0 1 2 3 4

Color Beige Red White Yellow Green Orange

Voltage 500 V 1,000 V 7,500 V 17,000 V 26,500 V 36,000 V

Table 1 — Glove rating range and colors.

Even though there exists standards that allow for glove patching, most testing and certification experts will not repair gloves that fail his testing, insisting that replacement is the only action for ultimate safety. Hot sticks, on the other hand, may be refurbished to like-new condition, and can be tested and returned to service.

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Arc Flash Safety Handbook — Volume 1

FR garment providers suggest wearing enough clothing to ensure that the clothing absorbs as much of the arc’s energy as possible – this is known as the garment’s Arc Rating. The heavier the fabric the higher the Arc Rating. Hazard/Risk Category Clothing Description 0

1 Figure 2 — Hot sticks may be refurbished to like new condition and must be tested annually

OSHA 1910.335(a)(1)(i) states that employers are responsible for providing all appropriate equipment needed by the company and for the employees to do their jobs safely and in compliance with OSHA standards. Some choices seem simple: arc flash protection requires an arc flash suit. But what about everyday wear? Will a technician consistently wear the highest level of protection every time? Maybe not. To address this issue, fire resistant (FR) apparel makers are designing lighter, more comfortable and flexible clothing, as well as offering more variety – from Henley style shirts and hooded sweats to FR rainwear. Today’s FR clothing is assigned a Hazard Risk Category (see Table 2), which corresponds to the arc thermal performance value (ATPV) and helps ease the employer’s evaluation of proper protection. ATPV is defined in ASTM F 1959-99 as one where there is a 50 percent chance of second degree burn with no under layers or for a breakopen. The idea behind the NFPA 70E Table is to use hazard/risk categories to help an employer choose the proper PPE for the corresponding application. Five categories defined in ASTM F 1506-02ae1 (Standard Performance Specification for Flame Resistant Textile Materials for Wearing Apparel for Use by Electrical Workers Exposed to Momentary Electric Arc and Related Thermal Hazards) that range from 0 to 4 are used by ASTM to assign protective categories for FR clothing based on incident energy. This number should be clearly indicated on a garment. OSHA 1910.269 for electrical worker’s apparel compliance means a worker’s clothing will not melt, ignite or continue to burn during an arc flash or fire exposure – a fire resistant garment can help satisfy this requirement. In 29CFR 1910.335 OSHA states that employees exposed to the hazard of arc flash shall wear PPE that is appropriate for the specific parts of the body to be protected and for the work to be performed. The key word being appropriate, not too little, not too much.

2

3

4

Minimum Arc Rating of PPE cal/cm2 – ( J/cm2)

Nonmelting flammable materials – such as untreated cotton, rayon, silk, wool, or blend – of fabric weight at least 4.5 oz. (1 layer)

N/A

4

(16.74)

Cotton underwear plus FR shirt and FR pant or FR coverall (1or 2 layers)

8

(33.47)

Cotton underwear plus FR shirt and FR pant plus multilayer flash suit (3 or more layers)

40

FR shirt and FR pant or FR coverall (1 layer)

25 Cotton underwear plus FR shirt and FR pant or FR coverall; or cotton underwear plus 2 FR coveralls (2 or 3 layers)

(104.6)

(167.40)

Table 2 — PPE Clothing Characteristics

The task of getting employees to wear bulky and inflexible garments while working in cramped or hot environments 2 has never been easy A 65 cal/cm jacket may offer the best protection, but will be useless if it sits in the back of a technician’s truck on a 96-degree August day. So in addition to the required flash protection suits technicians must wear, you may decide another approach for everyday wear that offers the protection and that you know an employee will consistently wear, and not unbutton or roll up the sleeves. One method to increase FR protection, while maintaining flexibility, is through layering; for example, wearing a sweatshirt over a Henley. The air between the two shirts has been shown to provide an additional layer of protection, about 50 percent more protection than the sum of the two garments separately. Cost, always a consideration must be gauged against the consequences. Maybe an employer is not in a position to fully outfit every technician today. There are minimal levels to acquire – what those levels are will be up to an individual company’s analysis. But once you an employee is outfitted, say for $1,000.00, maintaining that level of protection could drop to $200.00 a year. Considering that a litigation settlement from one unprotected employee could equal the price of outfitting hundreds of employees for a lifetime, you may want to reprioritize the PPE budget. Additionally, the employer is responsible to ensure clothing retains its flame retardant properties through conditions of use and laundering; therefore, it is important that employees understand about the care of FR clothing.

60 Some items are dry cleanable, but most are wash in cold or warm water and tumble dry; however, do not use fabric softeners or detergents with softeners as they can leave a residue on the garment. Quite simply, read the labels that come with the apparel. After having conducted an arc flash analysis, determined the level of PPE and selected a style of PPE, it is just a matter of ordering 30 XLs, 15 Ls and one or two XXLs for good measure. For some PPE that’s fine; however, the best method is to have staff measured and fit tested, from gloves to arc flash suits. This will help ensure comfort and optimal performance, and that the PPE will be consistently worn by employees. Before placing the order confirm PPE requirements with individual industries and their sites before purchasing PPE. For example, you may buy 30 Indura® FR shirts only to discover that the petrochemical industry insists on Nomex®. You may even be surprised to discover that the management of individual plants require only a specific color of material be worn on their site. In addition to OSHA, the Occupational Safety and Health Act of 1970 created the National Institute for Occupational Safety and Health (NIOSH). NIOSH, which dedicates its own laboratory, the National Personal Protective Technology Laboratory (NPPTL), to advancing federal research on PPE technologies, has investigated dozens of work-related electrocutions over the past decade (www. cdc.gov/niosh/injury/traumaelface.html). Many of them cite lack of or incorrect use of PPE, from no arc warning labels to wet gloves. Their conclusions often recommend the lockout/tagout procedure for working with live or potentially live electrical systems. Employers must develop energy control procedures for shutting down, isolating, blocking and securing machines or equipment to control hazardous energy. The fundamental reason for having a lockout / tagout procedure is that there is a lock with one key for every person involved in any electrical systems operation. Unlike a lockout, a tagout procedure alone may not include physically locking out the switchgear. This could allow the switchgear to be placed in the remote position, thereby making it possible to operate and energize systems from outside the equipment room where technicians are working. While lockout procedures are not fail-safe, physically isolating electrical components with locks, with keys controlled by the workers performing the work in the compartment, provides an additional level of protection, and, in most cases, is required by OSHA. Finally, arc flash hazard warning labels can be considered a simple, yet effective, form of PPE, indicating the level of PPE needed and the arc flash and shock protection boundaries. If the employee knows and understands the hazards and what is expected, the battle is half over when it comes to safe work practices.

Arc Flash Safety Handbook — Volume 1 PPE Advancements Employers should keep an eye out for advancements in PPE to help ensure that employees will wear the appropriate apparel. For example: 1. Rubber gloves that are not rubber. Although not as flexible as natural rubber, Dupont’s EPDM is a synthetic material that is oil resistant, ozone resistant, and resists sun-checking.

2. Arc resistant and fire resistant rainwear is now available.

3. Arc flash suits with small fans on the back are available. This increases comfort and reduces mask fogging. Manufacturing advancements in the works include injected molded gloves that promise to provide more dexterity and comfort. Developers are also working with carbon-based fibers to increase the durability of and protection offered by garments. Fortunately, according to the Bureau of Labor Statistics’ data, overall worker safety, in general, has increased over the past ten years, including the electrical industry – from 548 electrical-related fatalities (out of a total 6,588 deaths) in 1994 to 353 electrical (out of a total 5,559) work-related fatalities in 2003. However, independent analysts estimate that there are more than 2,000 arc flash related burn injuries a year where there is greater than 50 percent second degree burns to the body. This number is far too many. The good news is that employers can reduce these numbers through the procurement and maintenance of employees’ PPE and instruction in its use. Charlie Simpson is the Technical Writer for Burlington Electrical Testing Co. (BET, www.betest.com, Croydon, PA). BET, a NETA Accredited Company, is an independent electrical testing and maintenance company servicing the industrial, commercial, construction, medical and utility industries for all manufacturers of power generation and distribution equipment in the low to EH voltages.

Acknowledgements BET appreciates the contributions of Peter Senin, president of Burlington Safety Labs and Kevin McLaughlin of Tyndale who contributed their expertise to this article, and thanks Jim White of Shermco for reviewing the accuracy of this article. Photo courtesy of Burlington Safety Laboratory, Inc.

References 1. The Maintenance & Testing of Rubber Goods, Burlington Safety Laboratory, Inc. 2. NFPA 70E, Table 130.7(C)(11), Protective Clothing Characteristics.

NETA Accredited Companies The following is a listing of all NETA Accredited Companies as of June 4, 2009. Please visit the NETA website at www.netaworld.org for the most current list. A&F Electrical Testing, Inc.....................................................................Kevin Chilton Advanced Testing Systems..................................................... D. Patrick MacCarthy American Electrical Testing Co........................................................ Scott A. Blizard Apparatus Testing and Engineering .................................................... James Lawler Applied Engineering Concepts ................................................ Michel Castonguay Burlington Electrical Testing Company, Inc. ......................................Walter Cleary C.E. Testing, Inc. ...............................................................................Mark Chapman DYMAX Holdings, Inc. ..........................................................................Gene Philipp Eastern High Voltage ......................................................................... Joseph Wilson Electric Power Systems, Inc. .....................................................................Steve Reed Electrical and Electronic Controls ..................................................Michael Hughes Electrical Energy Experts, Inc. .............................................................William Styer Electrical Engineering Consulting & Testing, P.C. ........................ Barry W. Tyndall Electrical Equipment Upgrading, Inc. ....................................................Kevin Miller Electrical Reliability Services .................................................................. Lee Bigham Electrical Testing Services ..................................................................... Frank Plonka Electrical Testing, Inc. ..............................................................................Steve Dodd Elemco Testing Co. Inc. .....................................................................Robert J. White ESCO Energy Services ........................................................................ Lynn Hamrick Hampton Tedder Technical Services .................................................... Matt Tedder Harford Electrical Testing Co., Inc. ............................................... Vincent Biondino High Energy Electrical Testing, Inc. .................................................James P. Ratshin High Voltage Maintenance Corp. .........................................................Tom Nation HMT, Inc. ................................................................................................ John Pertgen Industrial Electric Testing, Inc. ...................................................... Gary Benzenberg Industrial Electronics Group.................................................................. Butch E. Teal Infra-Red Building and Power Service ...................................... Thomas McDonald M&L Power Systems Maintenance, Inc. ...........................................Darshan Arora

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Magna Electric Corporation ................................................................... Kerry Heid Magna IV Engineering – Edmonton ..............................................Jereme Wentzell Magna IV Engineering, Ltd. – BC ...................................................... Cameron Hite MET Electrical Testing Co., Inc. .................................................. William McKenzie Nationwide Electrical Testing, Inc. ........................................... Shashikant B. Bagle North Central Electric, Inc. .............................................................. Robert Messina Northern Electrical Testing, Inc. ........................................................Lyle Detterman Orbis Engineering Field Services, Ltd. ................................................... Lorne Gara Phasor Engineering ..............................................................................Rafael Castro Potomac Testing, Inc. ................................................................................Ken Bassett Power & Generation Testing, Inc.........................................................Mose Ramieh Power Engineering Services, Inc. ...................................................Miles R. Engelke Power Plus Engineering, Inc. ......................................................Salvatore Mancuso Power Products & Solutions, Inc. ......................................................Ralph Patterson Power Services, Inc. .......................................................................... Gerald Bydash Power Systems Testing Co. ............................................................... David Huffman Power Test, Inc. ................................................................................. Richard Walker Power Testing and Energization, Inc. ............................................... Chris Zavadlov Powertech Services, Inc. .................................................................... Jean A. Brown PRIT Service, Inc. ..........................................................................Roderic Hageman Reuter & Hanney, Inc. ....................................................................... Michael Reuter REV Engineering, Ltd. .....................................................................Roland Davidson Scott Testing, Inc. .................................................................................. Russ Sorbello Shermco Industries, Inc. ...........................................................................Ron Widup Sigma Six Solutions, Inc. ..........................................................................John White Southwest Energy Systems LLC ......................................................Robert Sheppard Taurus Power and Controls, Inc. ............................................................Rob Bulfinch Three-C Electrical Company, Inc. ......................................................James Cialdea Tony Demaria Electric, Inc. ...........................................................Anthony Demaria Trace Electrical Services & Testing LLC ................................................Joseph Vasta Utilities Instrumentation Service, Inc....................................................... Gary Walls Utility Service Corporation ..................................................................Alan Peterson

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About the InterNational Electrical Testing Association The InterNational Electrical Testing Association (NETA) is an accredited standards developer for the American National Standards Institute (ANSI) and defines the standards by which electrical equipment is deemed safe and reliable. NETA Certified Technicians conduct the tests that ensure this equipment meets the Association’s stringent specifications. NETA is the leading source of specifications, procedures, testing, and requirements, not only for commissioning new equipment but for testing the reliability and performance of existing equipment.

CERTIFICATION Certification of competency is particularly important in the electrical testing industry. Inherent in the determination of the equipment’s serviceability is the prerequisite that individuals performing the tests be capable of conducting the tests in a safe manner and with complete knowledge of the hazards involved. They must also evaluate the test data and make an informed judgment on the continued serviceability, deterioration, or nonserviceability of the specific equipment. NETA, a nationally-recognized certification agency, provides recognition of four levels of competency within the electrical testing industry in accordance with ANSI/NETA ETT-2000 Standard for Certification of Electrical Testing Technicians.

QUALIFICATIONS OF THE TESTING ORGANIZATION An independent overview is the only method of determining the long-term usage of electrical apparatus and its suitability for the intended purpose. NETA Accredited Companies best support the interest of the owner, as the objectivity and competency of the testing firm is as important as the competency of the individual technician. NETA Accredited Companies are part of an independent, third-party electrical testing association dedicated to setting world standards in electrical maintenance and acceptance testing. Hiring a NETA Accredited Company assures the customer that: • The NETA Technician has broad-based knowledge — this person is trained to inspect, test, maintain, and calibrate all types of electrical equipment in all types of industries. • NETA Technicians meet stringent educational and experience requirements in accordance with ANSI/NETA ETT-2000 Standard for Certification of Electrical Testing Technicians. • A Registered Professional Engineer will review all engineering reports. • All tests will be performed objectively, according to NETA specifications, using calibrated instruments traceable to the National Institute of Science and Technology (NIST). • The firm is a well-established, full-service electrical testing business.

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