Singapore Standards CP88: Code of Practice Part 1: Temporary Electrical Installations for Construction and Building Site...
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CP 88 : Part 1 : 2001
(ICS 29.260.10)
SINGAPORE STANDARD
Code of practice for temporary electrical installations – Part 1 : Construction and building sites Incorporating Erratum No. 1 Amendment No. 1 (issued separately)
Published by
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CP 88 : Part 1 : 2001 (ICS 29.260.10)
SINGAPORE STANDARD
Code of practice for temporary electrical installations – Part 1 : Construction and building sites
All rights reserved. Unless otherwise specified, no part of this Singapore Standard may be reproduced or utilised in any form or by any means, electronic or mechanical, including photocopying and microfilming, without permission in writing from SPRING Singapore at the address below:
Standards SPRING Singapore 1 Fusionopolis Walk, #01-02 South Tower, Solaris Singapore 138628 Email :
[email protected]
ISBN 9971-67-837-3
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CP 88 : Part 1 : 2001 This Singapore Standard having been approved by the Electrical Industry Practice Committee was endorsed by the Standards Council on 22 February 2001. First published, 2001 The Electrical Industry Practice Committee appointed by the Standards Council consists of the following members: Name
Organisation
Chairman
:
Mr Soh Siew Cheong
Standards Council
Secretary
:
Mr Dennis Chew
Singapore Productivity and Standards Board
Members
:
Assoc Prof Chang Che Sau Mr Foo Kong Deen Mr Goh Eng Kee Mr Ho Fui Chan
National University of Singapore Singapore Electrical Trade Association Ngee Ann Polytechnic Housing & Development Board
Mr Ho Sou Weng Er. N P Karthigayan
Singapore Polytechnic Institution of Engineers Singapore
Mr Bernard Koh Mr Leong Kok Yeong Mr Samuel Ong Bor Hwee Mr Pang Toh Kang Mr Tan Sing Ong Assoc Prof Teo Cheng Yu Mr Wan Fook Sing Mr Wu Ching Chan Mr Yeo Yek Seng
Institute of Technical Education Association of Consulting Engineers, Singapore Singapore Electrical Contractor Association PWD Corporation Pte Ltd Jurong Town Corporation Nanyang Technological University Singapore Contractor Association Limited Temasek Polytechnic Public Utilities Board
The Technical Committee on Temporary Electrical Installations appointed by the Electrical Industry Practice Committee and responsible for the preparation of this Part of the Code consists of representatives from the following organisations: Name
Organisation
Chairman
:
Mr Tan Hak Khoon
Public Utilities Board
Secretary
:
Ms Jessie Chow
Singapore Productivity and Standards Board
Members
:
Mr Foo Meng Wah Mr Jimmy Ho
Ministry of Manpower Real Estate Developers’ Association of Singapore Singapore Contractors Association Ltd
Mr Simon Lee∗ Mr Lim Ah Hee Er. Lum Chong Chuen Mr Ng Kim Leong
∗
Housing & Development Board Institution of Engineers Singapore PWD Corporation Pte Ltd
served until 2 June 2000
2
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CP 88 : Part 1 : 2001
Members
:
Mr Ng Kin Ming Mr Pang Boon Kiat Mr T Gopala Krishna Rao Mr Rozario Robert Er. Ken Tan See Pian Mr Toh Teck Boon Mr Yee Cheong In Mr Yong Siew Hwa
Singapore Electrical Contractors Association Power Supply Ltd Singapore Institution of Safety Officers Association of Singapore Marine Industries Association of Consulting Engineers, Singapore Singapore Electrical Trades Association Singapore Productivity and Standards Board Building and Construction Authority
3
As amended May 2001
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CP 88 : Part 1 : 2001
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CP 88 : Part 1 : 2001
Contents Page Foreword
8
CODE OF PRACTICE 1
General
9
1.1
Scope
9
1.2
Object
9
1.3
Relationship with statutory regulations
9
1.4
Use of established materials, equipment and methods
10
1.5
New materials and inventions
10
2
Definitions
10
3
General requirements
11
3.1
Source of supply
11
3.1.1
General
11
3.1.2
Types of supply
11
3.1.3
No parallel operation of generating set and the public electricity supply system
12
3.1.4
Supply for equipment
12
3.2
Type of earthing arrangement
12
3.3
Installation of generating set
13
3.3.1
General
13
3.3.2
Earthing arrangements of generating set
13
3.3.3
Protection against direct contact of live parts
13
3.3.4
Labelling on generating set
13
4
Protection for safety
14
4.1
Control of supply
14
4.1.1
General
14
4.1.2
Protective device for incoming supply
14
4.1.3
Protection of circuits
14
4.1.4
Prohibited use of fuses for final circuits
14
4.2
Protection against direct contact
15
4.3
Protection against indirect contact for low voltage system
15
4.3.1
General
15
4.3.2
Protection by residual current device
15
4.3.3
Protection by residual current device for final circuits
15
4.3.4
Earth leakage protection for transportable electrical equipment
16
4.3.5
Protective conductor proving and earth monitoring systems
16
4.4
Protection against indirect contact for reduced voltage system
16
5
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CP 88 : Part 1 : 2001 Page 4.5
Protection against lightning
16
5
Selection and erection of equipment
17
5.1
General
17
5.2
Wiring systems
17
5.3
Switchgear and controlgear
19
5.3.1
Enclosure for low-voltage assembly
19
5.3.2
Switchboard and distribution board
19
5.4
Socket-outlets assembly
19
5.5
Plugs, socket-outlets and cable couplers
23
5.6
Cable for SOA connection
23
5.7
Earthing arrangement and protective conductor
24
5.7.1
Protective earthing of metalwork
24
5.7.2
Earthing of portable appliances and tools
24
5.7.3
Earthing of metal sheath and armour of cables
24
5.7.4
Metal sheath and/or armour of flexible or trailing cables
24
5.7.5
Earthing of metal enclosure for switchboards and distribution boards
24
5.8
Other equipment
24
5.8.1
Light fixtures
24
5.8.2
Portable hand-lamps
24
5.8.3
Prohibited use of lampholders fitted with pin contacts
24
5.8.4
Electrical welding system
25
5.9
Equipment for reduced voltage system
25
5.9.1
Plug, socket-outlet and cable coupler of a reduced voltage system
25
5.9.2
Switches for reduced voltage circuits
25
6
Inspection, testing and maintenance
25
ANNEXES A
Statutory regulations and associated memoranda
26
B
Protective conductor proving and earth monitoring systems
27
C
Temporary electrical installations inspection checklist for construction and building sites
31
D
Danger signboard
36
E
Clauses that are extracted from British Standards
37
6
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CP 88 : Part 1 : 2001 Page TABLES 1 2
Maximum earth fault loop impedance (Zs) for a disconnection time 5s and Uo of 55V (single-phase)
16
Colour coding
23
FIGURES 1
Single-phase socket-outlet assembly fed from single-phase source
21
2
Single-phase socket-outlet assembly fed from three-phase source
21
3
Three-phase socket-outlet assembly
22
4
Three-phase and single-phase socket-outlet assembly
22
B1
Basic circuit for protective conductor proving unit
29
B2
Basic circuit for earth monitoring unit
30
7
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CP 88 : Part 1 : 2001
Foreword This Part of the Singapore Standard CP 88 was prepared by the Technical Committee on Temporary Electrical Installations under the direction of the Electrical Industry Practice Committee. It was developed as a result of a review of the Singapore Standard CP 44 : 1988 – ‘Code of practice for temporary electrical installations for construction and building sites’. This Part of CP 88 is drawn up to supplement the general requirements of Singapore Standard CP 5 – ‘Code of practice for electrical installations’. As installations operating at voltages up to 1000 V a.c. are widely used in construction and building sites, it is considered necessary to give guidance on good practice for the inspection, testing and maintenance of such installations. In addition, guidance on the installation of generating set and socket-outlet assembly are included to address the common use of generating set and socket-outlets for portable tools at these sites. It is to be noted that for installations where separated extra low voltage (SELV) is used, references shall be made to the general requirements for protection by SELV in Singapore Standard CP 5. Installations operating at voltages exceeding low voltage are outside the scope of this Part of the Code. NOTE – Temporary electrical installations other than that for Construction and Building Sites may be covered in other Parts of this Code.
Acknowledgement is made for the use of information from the following publications: AS 2790 : 1989
Electricity generating sets – Transportable (Up to 25 kW)
AS 3010.1 : 1987
Electrical installations – Supply by generating set Part 1 – Internal combustion engine driven set
BS 4363 : 1998
Specification for assemblies for reduced low voltage electricity supplies for construction and building sites
BS 4444 : 1989
Guide to electrical earth monitoring and protective conductor proving
BS 5345 : -
Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmosphere (other than mining applications or explosive processing and manufacture)
BS 6500 : 2000
Specification for electric cables – Flexible cords rated up to 300/500 V, for use with appliances and equipment intended for domestic, office and similar environments
BS 6708 : 1998
Flexible cables for use at mines and quarries
BS 7375 : 1996
Code of practice for distribution of electricity on construction and building sites
Clauses that are extracted from the above British Standards are given in Annex E. reproduced with the permission of British Standards Institution (BSI).
They are
NOTE 1.
Singapore Standards are subject to periodic review to keep abreast of technological changes and new technical developments. The revisions of Singapore Standards are announced through the issue of either amendment slips or revised editions.
2.
Compliance with a Singapore Standard does not exempt users from legal obligations.
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CP 88 : Part 1 : 2001
Code of practice for temporary electrical installations – Part 1: Construction and building sites 1
General
1.1
Scope
This Part of the Code of Practice deals principally with temporary electrical installations for building operation and work of engineering construction. It applies to electrical installations set up for the provision of electricity supply during the execution of the following works: (a)
New building construction;
(b)
Repair, alteration, extension or demolition of buildings;
(c)
Engineering construction;
(d)
Earthworks;
(e)
Other similar works.
The requirements in this Code shall not apply to installations in construction site offices, meeting rooms, canteens, dormitories, toilets, etc., where the general requirements in the Singapore Standard CP 5 shall apply. Although some temporary installations at these sites may receive supplies at voltages higher than 1000 V, such parts of the installations are outside the scope of this Code. This Code also does not cover those aspects of installations in compressed air environment and potentially explosive atmospheres. NOTE – The titles of the publications referred to in this standard are listed at the end of the standard.
1.2
Object
The object of this Part of the Code is to protect persons and property against electrical hazards in the use of electricity in construction sites in view of the arduous duty imposed on the electrical equipment and wiring by the construction site conditions. The general requirements of Singapore Standard CP5 shall be read in conjunction with this Part of the Code. Because of variations in local circumstances of construction sites, the requirements of this Code are given in general terms, and will normally need to be supplemented by the advice of skilled persons as defined in 2.7.
1.3
Relationship with statutory regulations
This Part of the Code is to be implemented in conjunction with other statutory requirements currently in force in the Republic of Singapore and should there be any conflicting requirements in the Acts and their Regulations, clarification should be obtained from the relevant bodies administrating the Acts and Regulations.
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CP 88 : Part 1 : 2001 All temporary electrical installations for building operation and work of engineering construction are required to be licensed by the Public Utilities Board under the Public Utilities (Licence to Use or Operate Electrical or Supply Installations) Regulations.
1.4
Use of established materials, equipment and methods
Only established materials, equipment and methods are considered, but it is not intended to discourage invention or to exclude other materials, equipment and methods affording an equivalent degree of safety which may be developed in the future.
1.5
New materials and inventions
Where the use of a new material or invention leads to departures from this Part of the Code, the resulting degree of safety of the installation is to be not less than that obtained by compliance with this Part of the Code. Such departure shall be the subject of a written specification of a competent body, or skilled person or persons, and the installation shall be deemed to be outside the scope of this Part of the Code.
2
Definitions
For the purposes of this Code, the following definitions shall apply. Other terms not defined herein are used in the sense defined in Singapore Standard CP 5.
2.1
Cable coupler
A cable coupler is a means enabling the connection at will of two flexible cables. It consists of two parts: (a)
A connector, which is the part integral with, or intended to be attached to, the flexible cable connected to the supply;
(b)
A plug, which is the part integral with, or intended to be attached to, the flexible cable connected to the equipment or to a connector.
The plug of a cable coupler is identical to the plug of a 'plug and socket-outlet'. In general, a connector has the same contact arrangement as a socket-outlet.
2.2
Earth monitoring system
A system for providing a means of maintaining a high degree of confidence in the measured impedance of a protective conductor forming part of the earthing arrangements of an electrical system.
2.3
Generating set
A generating set is an internal combustion engine driving a rotating a.c. electrical generator together with its associated control panel, switchgear and ancillary equipment, whether integrally mounted or otherwise.
2.4
Plug
A device, provided with contact pins, which is intended to be attached to a flexible cable, and which can be engaged with a socket-outlet or with a connector.
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CP 88 : Part 1 : 2001 2.5
Protective conductor proving system
A system for providing a means of maintaining a high degree of confidence in the continuity of a protective conductor within the installation.
2.6
Readily accessible
Capable of being reached quickly, for operation, renewal, or inspection without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc.
2.7
Skilled person
A person who is licensed as an electrical worker under the Electrical Workers and Contractors Licensing Act.
2.8
Site
An area where a building operation or work of engineering construction takes place.
2.9
Socket-outlet
A device, provided with female contacts, which is intended to be installed with the fixed wiring, and intended to receive a plug. A luminaire track system is not regarded as a socket-outlet system.
2.10
Supplies
All references throughout this Code refer to alternating current (a.c.) supplies related to a frequency of 50 Hz unless otherwise stated. All references to alternating voltage and current relate to r.m.s. values unless otherwise stated.
3
General requirements
3.1
Source of supply
3.1.1
General
Electrical installation at site may draw its supplies from the public electricity supply network or generating sets. Equipment shall be identified with and be compatible with the particular supply from which it is energised and shall contain only components connected to one and the same installation, except for control of signalling circuits and inputs from standby supplies. Due consideration shall be given to the fault level (prospective short-circuit current) at the point of supply. 3.1.2
Types of supply
3.1.2.1 Mains voltages of public supply system (a)
Three-phase.
400 V is the standard three-phase mains supply system voltage at 50 Hz.
(b)
Single-phase.
230 V is the standard single-phase mains supply system voltage at 50 Hz.
3.1.2.2 Supply voltage from generating sets For a generating set supplying low voltages, unless otherwise approved by the skilled person responsible for the design and installation of supply installation, the output voltages shall be as follows:
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CP 88 : Part 1 : 2001 (a)
Three-phase.
400 V between phases, and 230 V between phases and Earth, 50 Hz.
(b)
Single-phase.
230 V between phase and Earth, 50 Hz.
3.1.2.3 Reduced voltage 110 V single-phase. The supply shall be obtained from a double-wound transformer having the centre tap of the secondary winding earthed so that the nominal voltage to Earth is only 55 V. 3.1.2.4 Extra low voltage 50 V single-phase. The supply shall be obtained from a double-wound transformer having the centre tap of the secondary winding earthed so that the nominal voltage to Earth is only 25 V. 3.1.3
No parallel operation of generating set and the public electricity supply system
No parallel operation of the generating set and the public supply system shall be allowed unless otherwise approved by the public electricity supplier. In a service area where electricity supply is taken from a generating set, no electricity supply from the public supply system shall be introduced into the same service area. 3.1.4
Supply for equipment
The following voltages shall not be exceeded: (a)
Fixed plant, moveable plant fed via a trailing cable, installations in site buildings such as site offices, workshops, canteens and quarters, fixed flood lighting and site lighting.
400 V 230 V
Three-phase, or Single-phase
(b)
Portable electric hand-held tools and portable handlamps.
230 V
Single-phase
(c)
Portable electric hand-held tools and portable handlamps used underground such as any shaft, tunnel, caisson or cofferdam.
110V
Single-phase, centre point earthed
(d)
Portable electric hand-held tools and portable handlamps used in confined locations such as the insides of boilers, tanks or pipes, or in other similar situations.
50V
Single-phase, centre point earthed
3.2
Type of earthing arrangement
3.2.1 The earthing system for electrical installations drawing supply from generating sets shall be TN-S. 3.2.2
If more than one generating set are used within a site, the electrical installations shall either:
(a)
Share a common earthing system; or
(b)
Have separate earthing systems and the electrical installations connected to different earthing systems are segregated effectively from one another or effectively bonded to prevent dangerous potential rise between conducting parts which a person can come into simultaneous contact.
This requirement also applies to more than one electrical installations taking supply from the public supply system within the same site.
12
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CP 88 : Part 1 : 2001 3.2.3 The design, selection and installation of protective conductors shall be in accordance with Singapore Standard CP 5.
3.3
Installation of generating set
3.3.1
General
Generating set shall be suitably barricaded to prevent access by non-authorised persons. Adequate clearance around generating set shall be provided to facilitate operation and maintenance work. Access leading to the generating sets shall be unimpeded to the skilled person or his representatives at all times. Any switch or control for stopping and starting the engines shall be readily accessible. In addition, generating set shall not be installed: (a)
In damp situations or exposed to the weather unless suitably protected; or
(b)
In hazardous areas, unless the equipment and method of installation complies with BS 5345 and the additional requirements of any relevant authority.
Care shall be taken to have the fuel and its containers stored in a safe manner. 3.3.2
Earthing arrangements of generating set
Electrical installation supplied from generating sets shall share a common TN-S earthing system with the generator or generators connected to it. In any electrical installation, a main earthing terminal or bar of adequate rating shall be provided and connected to the earthing conductors. The star point of a three-phase generator winding or the mid-point of a single-phase centre-tapped generator winding shall be solidly earthed through adequately rated conductors to the earthing system of the installation. In addition, the following parts of the generating sets shall be bonded together to form the generator bonding system which shall be connected effectively to the main earthing terminal: (a)
The engine frame;
(b)
The generator frame;
(c)
All exposed metal enclosure for electrical equipment and wiring;
(d)
Earth terminals of all socket-outlet (if any); and
(e)
The main frame terminal (marked
3.3.3
Protection against direct contact of live parts
)
All live parts of a generating set shall be protected against direct contact in accordance with Singapore Standard CP 5. 3.3.4
Labelling on generating set
The following information shall be indelibly and legibly marked on a generating set: (a)
The name of the manufacturer of the set;
(b)
The model number and serial number of the set;
(c)
The type of fuel or fuel-oil mixture;
(d)
Rated output in watts or kilowatts at a stated power factor;
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CP 88 : Part 1 : 2001 (e)
The voltage and frequency;
(f)
Output terminal markings (unless all outputs are socket-outlets);
(g)
The frame terminal : symbol marked
(h)
On a set intended for undercover or weather-protected usage, the words “NOT WEATHERPROOF”;
(i)
On a set intended for outdoor use without further protection, the IP classification of its electrical equipment;
(j)
In addition, a danger sign board made of durable material with the word DANGER with the specification as detailed in Annex D shall be displayed at a prominent location near the generating set.
4
Protection for safety
4.1
Control of supply
4.1.1
General
;
Every electrical installation on construction sites shall be adequately controlled by switchgear readily accessible to the skilled person or his authorised representative in charge of the installation and shall incorporate: (a)
Means of isolation;
(b)
Means of overcurrent and earth fault protection; and
(c)
Means of earth leakage protection (except extra-low voltage installations)
4.1.2
Protective device for incoming supply
For an incoming supply up to 300 A three-phase, a circuit breaker with residual current device shall be provided at the main switchboard. For an incoming supply exceeding 300 A three-phase, a circuit breaker incorporating overcurrent and earth fault protective devices shall be provided. 4.1.3
Protection of circuits
Appropriate electrical protection shall be provided for all circuits, including final circuits, against overload, short-circuit and earth-fault current. The protective devices shall be capable of interrupting without damage any fault current that may occur and due consideration shall be given to the fault level of the supply. 4.1.4
Prohibited use of fuses for final circuits
Fuses shall not be used for protecting final circuits in any part of the installation, except for those socket-outlets incorporated with fuse protection.
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CP 88 : Part 1 : 2001 4.2
Protection against direct contact
One or more of the following basic protective measure shall be used in accordance with the requirements in Singapore Standard CP 5: (a)
Protection by insulation of live parts,
(b)
Protection by a barrier or an enclosure,
(c)
Protection by obstacles,
(d)
Protection by placing out of reach.
4.3
Protection against indirect contact for low voltage system
4.3.1
General
Protection against indirect contact for low voltage system shall comply with clauses 4.3.2 to 4.3.3. 4.3.2
Protection by residual current device
Protection against indirect contact shall be afforded using residual current devices and the following condition shall be fulfilled as appropriate to the type of earthing system: For TN-S system:
Zs I∆n ≤ 25 V
where Zs is the earth fault loop impedance in ohms I∆n is the rated residual operating current of the protective device in amperes. For TT system:
Ra I∆n ≤ 25 V
where Ra is the sum of the resistances of the earth electrode and the protective conductor(s) connecting it to the exposed-conductive-part. 4.3.3
Protection by residual current device for final circuits
Except for final circuits supplying equipment which are protected by other appropriate measures as permitted under this Code and only accessible to and are operated by a skilled person, all other final circuits are to be protected by one or more residual current devices. The type and tripping sensitivities of residual current device to be used for the final circuit of the following rating shall be: (a)
Residual current circuit breaker with a tripping current not exceeding 30 mA and a tripping time within 0.1 s complying with SS 97 for final circuits of rating not exceeding 63 A threephase or single-phase at mains voltage.
(b)
Residual current circuit breaker with a tripping current not exceeding 300 mA complying with SS 97 for final circuits of rating exceeding 63 A but not more than 100 A three-phase or single-phase at mains voltage.
(c)
Residual current device with a tripping current not exceeding 500 mA shall be used for final circuits of rating exceeding 100 A three-phase at mains voltage.
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CP 88 : Part 1 : 2001 4.3.4
Earth leakage protection for transportable electrical equipment
For guidance on earth leakage protection for transportable electrical equipment, refer to Singapore Standard CP 16. 4.3.5
Protective conductor proving and earth monitoring systems
Where flexible cables supplying power at mains voltage to a moveable plant are liable to become damaged or discontinuous, a protective conductor proving and/or earth monitoring system shall be used to detect the failure of the circuit protective conductor. Annex B describes one such system which is recommended to detect the failure of the circuit protective conductor.
4.4
Protection against indirect contact for reduced voltage system
Protection against indirect contact for reduced voltage system by automatic disconnection shall be provided by means of an overcurrent protective device in each phase conductor or by a residual current device, and all exposed-conductive-parts of the reduced voltage system shall be connected to Earth. The earth fault loop impedance at every point of utilisation, including socket-outlets, shall be such that the disconnection time does not exceed 5 s. Where a circuit breaker is used, the maximum value of the earth fault loop impedance (Zs) shall not exceed the values specified in Table 1 below for the nominal voltages to Earth (Uo) and for the types and ratings of circuit-breaker listed herein. Where a residual current device is used, the product of the rated residual operating current in amperes and the earth fault loop impedance in ohms shall not exceed 25. Table 1 – Maximum earth fault loop impedance (Zs) for a disconnection time 5s and Uo of 55 volts (single-phase) MCB Type to SS 359 & BS EN 60898 Rating amperes (In) 6 10 16 20 25 32 40 50 63 80 100
4.5
1
B
2
C&3
D
Uo / 4 ln
Uo / 5 ln
Uo / 7 ln
Uo / 10 ln
Uo / 20 ln
2.29 1.38 0.86 0.69 0.55 0.43 0.34 0.28 0.22 0.17 0.14
1.83 1.10 0.69 0.55 0.44 0.34 0.28 0.22 0.18 0.14 0.11
1.31 0.79 0.49 0.39 0.31 0.25 0.20 0.16 0.13 0.10 0.08
0.92 0.55 0.34 0.28 0.22 0.17 0.14 0.11 0.09 0.07 0.06
0.46 0.28 0.17 0.14 0.11 0.09 0.07 0.06 0.04 0.03 0.03
Protection against lightning
In circumstances where protection against lightning on sites may be necessary, reference shall be made to Singapore Standard CP 33.
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CP 88 : Part 1 : 2001
5
Selection and erection of equipment
5.1
General
Every item of equipment shall be selected and erected so as to comply with the general requirements stipulated in the Singapore Standard CP 5 and the following clauses in this Section.
5.2
Wiring systems
The types of protective covering of cables used in all the site installations shall be selected in accordance with subclauses 5.2.1 to 5.2.5. 5.2.1 – 5.2.6 5.2.1
Types of cable covering
All cables to be laid direct in the ground shall be armoured cables.
5.2.2 Except for cables installed overhead, all other cables for submains or final circuits operating at voltages exceeding 63 V to Earth (Three-phase system) or 55 V to Earth (Single-phase system) and routed outdoor shall be of armoured construction and buried where possible. 5.2.3 All cables which are likely to be moved in normal use shall be flexible cables. Where trailing cables are required by nature of the work, they shall be of the armoured type complying with BS 6708 having an over-sheath of heavy duty oil-resisting and flame-retardant compound. 5.2.4 Elevated cables shall be fully insulated having a sheath of PVC or an oil-resisting and flameretardant or heat resisting sheath. Overhead cables exposed to sunlight shall comply with subclause 5.2.6. 5.2.5 Except for situations (e.g. switch rooms or control rooms) where the risk of mechanical damage is slight, armoured cables having an over-sheath of PVC or an oil-resisting and flameretardant compound or cables with adequate mechanical protection shall be used. 5.2.6 used.
For resistance to the effects of sunlight, suitable non-metallic covering of cables shall be
5.2.7 – 5.2.10
Flexible cords
5.2.7 Flexible cords shall be of the circular type having heat resisting, oil resisting and flameretardant rubber-sheath complying with IEC 60245 Part 1 or PVC insulated and PVC sheathed complying with SS 358 : Part 5. 5.2.8 Flexible cords for portable hand-lamps shall be of the circular type having screened Type EM2 rubber-sheath complying with BS 6500. 5.2.9 Flexible cords of portable electrical equipment shall not exceed 3 m in length or such length as supplied by the original equipment manufacturer. 5.2.10 Flexible cords of conductor size smaller than 1.0 mm² (32/0.20 mm) shall not be used. 5.2.11 – 5.2.26 Installation of cables 5.2.11 Cables, other than those supplying power to portable electrical equipment or mobile plant, shall be fixed on site so that they are clear of building operation or engineering construction work and are not a hazard to persons working on the site. 5.2.12 All cables are to be installed without obstruction to the use of passageways, walkways, ladders, stairs and the like.
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CP 88 : Part 1 : 2001 5.2.13 Where submains cables inside a building or under a covered area are to be suspended or supported from the ceiling or wall, cable trays, brackets or other suitable supports shall be provided. The cable supports shall not cause damage to the cable insulation or subject the cables to undue mechanical stress. 5.2.14 Laying of cables on the ground or the floor of a structure shall be avoided. Where it is unavoidable to lay cables on the ground or the floor of a structure, the cables shall be of the armoured type complying with BS 6708 having an over-sheath of heavy duty oil-resisting and flame-retardant compound or PVC insulated, steel wire armoured and PVC sheathed complying with SS 443 and shall be laid in such a manner that the risk of mechanical damage is prevented. 5.2.15 Elevated flexible cables used indoor shall be provided with suitable mechanical protection and securely supported in such a manner as not to damage the sheath of the flexible cables and not subject the cables or their terminations to undue mechanical stress. 5.2.16 No flexible cord shall be used as submain or final circuit for the purpose of distribution of electricity supply. 5.2.17 Cables buried direct in the ground shall be marked by cable covers and shall be buried at a minimum depth of 300 mm to avoid being damaged by any disturbance on the ground. The cable route for all supply cables and submains buried underground shall be marked on site drawings. 5.2.18 Cables passing under roadways or accessways for transport and mobile plant shall be laid at a minimum depth of 600 mm. A cable marker shall be installed at both ends of each crossing. 5.2.19 Overhead cables shall be so placed and at such height as to be out of reach of any source of mechanical damage reasonably to be foreseen in the area where they are erected. For cables to be installed outdoor, the requirement in subclause 5.2.6 shall be complied with. 5.2.20 Overhead cables shall be installed at a height such that a clear vertical distance between the lowest part of the overhead cables and the highest point of vehicles, mobile cranes or other mobile plant likely to pass underneath them is 2 m minimum but under no circumstances shall the clear height to ground of the overhead cables be less than 5 m where they cross roadways or accessways. 5.2.21 Overhead cables shall be supported by catenary wires or proper cable support in a manner such that the cables are not subjected to undue mechanical stress. The catenary wires or metallic cable support shall be effectively bonded to Earth. 5.2.22 Poles supporting overhead cables shall be so located or arranged that the risk of mechanical or vehicular damage is prevented. Poles shall be sufficiently sized with adequate mechanical strength and properly anchored. 5.2.23 Metal pole of minimum diameter 100 mm with adequate mechanical strength shall be used. Poles made of wood or plastic material shall not be used for this purpose. 5.2.24 All cables shall be installed so that they are at least 150 mm clear of piped services such as steam, gas and water and shall not be located directly below and parallel to these pipes. 5.2.25 All armoured cable terminations shall be provided with cable glands and earth tags for bonding to associated gland plate and adjacent cables in order to maintain satisfactory earth loop impedance. The armour of the cable shall not however be relied on as circuit protective conductor for the cable. 5.2.26 All joints shall be mechanically and electrically sound and fully insulated.
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CP 88 : Part 1 : 2001 5.3
Switchgear and controlgear
5.3.1
Enclosure for low-voltage assembly
5.3.1.1 The enclosure of each assembly for the distribution of electricity shall be robustly constructed so as to have adequate strength and rigidity to resist damage that could result from transportation, rough handling and heavy objects falling on it. 5.3.1.2 Except for socket-outlet assembly, the enclosure for outdoor installation shall have: (a)
A degree of protection of at least IP44 to ensure the safe and satisfactory operation of the enclosed equipment; and
(b)
A roof so designed to prevent stagnation of water on its surface.
NOTE – It is recommended that the roof shall extend at least 76 mm beyond the main body of the enclosure.
5.3.1.3 The enclosure shall be so placed, installed and safeguarded: (a)
To prevent damage by external influences that may affect the design and safe operation of the equipment; and
(b)
Shall be provided with adequate and safe means of access and working space for operation and maintenance purposes.
5.3.2
Switchboard and distribution board
5.3.2.1 Every switchboard and distribution board shall incorporate means for isolating and switching the incoming supply. Isolating switches or circuit breakers used for this purpose shall be suitable for securing in the OFF position. 5.3.2.2 Every switchboard and distribution board shall be erected to satisfy the requirements of Clause 4 of this Code.
5.4
Socket-outlets assembly
Socket-outlet assembly shall be used for the connection of portable electrical equipment at locations where fixed socket-outlets may not be available. The assembly shall fulfil the requirements described in subclause 5.4.1 to 5.4.5. 5.4.1
Enclosure for socket-outlet assembly
5.4.1.1 The enclosure for the socket-outlet assembly shall be fabricated from: (a)
Galvanised sheet steel of minimum 1.5 mm thickness finished in epoxy powder coating; or
(b)
Aluminium sheet of minimum 2 mm thickness finished in epoxy powder coating; or
(c)
Self-extinguishing, non-hygroscopic polycarbonate thermoplastic with high impact strength (6 joule), high resistance to UV rays, high resistance to chemical elements and high resistance to abnormal heat and fire (glow wire test according to SS 145 Part 2)
5.4.1.2 The degree of protection for the enclosure shall be of minimum IP44 to SS IEC 60529. 5.4.1.3 The enclosure can be of floor standing or wall mounting and shall be totally enclosed with all live parts protected from direct contact. Floor standing socket-outlet assembly shall be: (a)
Fitted with supports to afford a minimum clearance of 150 mm from the ground; and
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CP 88 : Part 1 : 2001 (b)
Provided with handles and lifting lugs.
5.4.1.4 Every cable connection to and from the enclosure shall be by means of plugs and socketoutlets. The plugs and socket-outlets shall be of the appropriate type specified in subclause 5.5. 5.4.2
Single-phase socket-outlet assembly fed from single-phase source
5.4.2.1 The assembly shall be fed from a 32 A single-phase 230 V source. 5.4.2.2 A fixed plug rated at 32 A single-phase 230 V shall be provided to receive the 32 A singlephase 230 V incoming supply. A 32 A double-pole MCB shall be provided to control the incoming supply. 5.4.2.3 A maximum of up to six numbers of 16A 2-pole and earth socket-outlets shall be provided. Each socket-outlet shall be controlled by a double-pole MCB not exceeding 16 A current rating. All socket-outlets shall be protected by residual current circuit breaker complying with Singapore Standard SS 97 having a rated residual current not exceeding 30 mA. 5.4.3
Single-phase socket-outlet assembly fed from three-phase source
5.4.3.1 The assembly shall be fed from a 32 A three-phase 400 V source. 5.4.3.2 A fixed plug rated at 32 A three-phase 400 V shall be provided to receive the 32 A three-phase 400 V incoming supply. A 32 A 4-pole MCB shall be provided to control the incoming supply. 5.4.3.3 A maximum of nine numbers of 16 A 2-pole and earth socket-outlets shall be provided. Each socket-outlet shall be controlled by a double-pole MCB not exceeding 16 A current rating. All socketoutlets shall be protected by residual current circuit breaker complying with Singapore Standard SS 97 having a rated residual current not exceeding 30 mA. 5.4.4
Three-phase socket-outlet assembly
5.4.4.1 The assembly shall be fed from a 32 A three-phase 400 V source. 5.4.4.2 A fixed plug rated at 32 A three-phase 400 V shall be provided to receive the 32 A three-phase 400 V incoming supply. A 32 A 4-pole MCB shall be provided to control the incoming supply. 5.4.4.3 A maximum of three numbers of 16 A 4-pole and earth socket-outlets shall be provided. Each socket-outlet shall be controlled by a TP&N MCB not exceeding 16 A current rating. All socket-outlets shall be protected by residual current circuit breaker complying with Singapore Standard SS 97 having a rated residual current not exceeding 30 mA. 5.4.5
Three-phase and single phase socket-outlet assembly
5.4.5.1 The assembly shall be fed from a 32 A three-phase 400 V source. 5.4.5.2 A fixed plug rated at 32 A three-phase 400 V shall be provided to receive the 32 A three-phase 400 V incoming supply. A 32 A 4-pole MCB shall be provided to control the incoming supply. 5.4.5.3 A maximum of two numbers of 16 A 4-pole and earth socket-outlets and a maximum of three numbers of 16 A 2-pole and earth socket-outlet shall be provided. Each socket-outlet shall be controlled by a TP&N MCB / double-pole MCB of current rating not exceeding 16 A. All socket-outlets shall be protected by residual current circuit breaker complying with Singapore Standard SS 97 having a rated residual current not exceeding 30 mA. 5.4.5.4 The schematic connection arrangements of the socket-outlet assemblies are shown in Figures 1 to 4.
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CP 88 : Part 1 : 2001
Figure 1 – Example of single-phase socket-outlet assembly fed from single-phase source
Figure 2 – Example of single-phase socket-outlet assembly fed from three-phase source
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CP 88 : Part 1 : 2001
Figure 3 – Example of three-phase socket-outlet assembly
Figure 4 – Example of three-phase and single-phase socket-outlet assembly
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CP 88 : Part 1 : 2001 5.5
Plugs, socket-outlets and cable couplers
5.5.1
All plugs, socket-outlets and cable couplers shall comply with the requirements of IEC 60309.
5.5.2 All plugs, socket-outlets and cable couplers likely to be exposed to the weather shall be contained in a weatherproof enclosure unless they are of the weatherproof type (minimum IP44 to SS IEC 60529). 5.5.3 Plugs of one voltage system shall not be capable of entering socket-outlets of other voltage systems used in the same site. 5.5.4 Plugs, socket-outlets and cable couplers of a 110 V single-phase operation shall be of the 3pin type and the ‘numbered hour position’ shall be 4H. NOTE – Numbered hour position indicates the position of earth contact-tube in relation to the keyway.
5.5.5 Plugs, socket-outlets and cable couplers for use with 230 V single-phase system shall be of the 3-pin type with the numbered hour position 6H. 5.5.6 Plugs, socket-outlets and cable couplers for use with 400 V three-phase system shall be of the 5-pin type, 3-pole and neutral and earth, and numbered hour position 6H. 5.5.7 Where several voltages are used in the temporary installation, all plugs, socket-outlets and cable couplers shall be identified by different colours as given in Table 2. Table 2 – Colour coding
5.5.8 – 5.5.9 5.5.8
Operating Voltage (V)
Colour
55
White
110
Yellow
230
Blue
400
Red
Connection to socket-outlets
Connection of flexible cables or flexible cords to socket-outlets shall be by means of plugs.
5.5.9 Where heavy electrical plants such as rail-mounted tower cranes requires the use of plugs and socket-outlets as a convenient form of connection at mains, such plugs and socket-outlets shall be mechanically interlocked. Electrical interlock can be used as an additional feature.
5.6
Cable for SOA Connection
An extension cable may be used to connect portable equipment to a SOA and such extension cable shall comply with the following conditions: (a)
the cable shall be appropriately sized and provided with suitable mechanical protection;
(b)
the cable shall be connected to an industrial plug of appropriate rating on one end and a switched industrial socket-outlet at the other end to facilitate emergency switching; and
(c)
the industrial plug and switched socket-outlet shall be as specified in clause 5.5.
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CP 88 : Part 1 : 2001 5.7
Earthing arrangement and protective conductor
Every earthing arrangement and protective conductor shall be selected and erected to comply with the requirements of the Singapore Standard CP 5. Attention shall also be paid to the need for equipotential bonding of extraneous metallic parts. 5.7.1
Protective earthing of metalwork
Metalwork not belonging to the installation including steel scaffolding which is liable to come into fortuitous contact and become live in the event of a failure of insulation of the installation shall be effectively earthed at all times. 5.7.2
Earthing of portable appliances and tools
Exposed metalwork of all portable appliances and tools shall be connected to the circuit protective conductors in the flexible cables or flexible cords unless they are double-insulated as specified in SS 236 or of extra-low voltage system. For further guidance, refer to the appropriate clause in Singapore Standard CP 16 on earthing of portable appliances and tools. 5.7.3
Earthing of metal sheath and armour of cables
Metal sheath and armour of cables shall be effectively earthed. However, the metal sheath or armour of the cable shall not be used as circuit protective conductor. 5.7.4
Metal sheath and/or armour of flexible or trailing cables
Metal sheath and/or armour of flexible or trailing cables shall not be the sole circuit protective conductor but in addition to the earth cores of the cables. 5.7.5
Earthing of metal enclosure for switchboards and distribution boards
Constructional precautions shall be taken to ensure electrical continuity between the exposed conductive parts of the switchboard and distribution boards and between these parts and the protective circuits of the installation.
5.8
Other equipment
5.8.1
Light fixtures
Light fixtures used outdoor or at locations where there is likelihood that such fixtures are subjected to water splashing shall be of the weatherproof type. Light fixtures installed shall be equipped with suitable guards if they are exposed to risk of mechanical damage. 5.8.2
Portable hand-lamps
Portable hand-lamps supplied through flexible cords shall be of the moulded composition or other type designed for the purpose and equipped with a handle. Hand-lamps shall also be equipped with substantial guard attached to the lampholder or the handle. 5.8.3
Prohibited use of lampholders fitted with pin contacts
The use of lampholders fitted with pin contacts intended to be penetrated into tough rubber sheath or polychloroprene sheath cable is prohibited.
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CP 88 : Part 1 : 2001 5.8.4
Electrical welding system
Every a.c. welding set must be equipped with low voltage shock preventor. The preventor shall effectively reduce the open circuit secondary voltage to a safe level not exceeding 25 V. The low voltage shock preventors shall be of the built-in type or be housed in a weatherproof metal casing and effectively secured or locked to prevent tampering by welders and other unauthorised persons. The workpiece should be connected to the return terminal of the welding set through a proper return conductor.
5.9
Equipment for reduced voltage system
5.9.1
Plug, socket-outlet and cable coupler of a reduced voltage system
Every plug, socket-outlet and cable coupler of a reduced voltage system shall have a protective conductor contact and shall not be dimensionally compatible with any plug, socket-outlet or cable coupler for use at any other voltage or frequency in the same installation. 5.9.2
Switches for reduced voltage circuits
Switches controlling single-phase supplies on installations operating up to and including 110 V shall be of the double-pole type with circuit protection provided in each line conductor.
6
Inspection, testing and maintenance
6.1
Electrical installation on site shall be inspected and tested in accordance with the requirements of Part 7 – Inspection and Testing of Singapore Standard CP 5 before installation is energised.
6.2
Strict maintenance and periodic inspection of the electrical installation and the wiring distribution system shall be carried out by a skilled person to promote safety and to ensure efficient operation.
6.3
All temporary electrical installations shall be inspected by a skilled person at least once a month. Upon completion of the inspection, the skilled person shall complete and sign the checklist shown in Annex C and hand it over to the operator of the electrical installation or his representative.
6.4
Where any defect or unsafe condition is revealed during the inspection, the skilled person shall take measures, such as by rectifying the defects, or by isolating or disconnecting the defective part or parts from electricity supply, to render the electrical installation safe. Appropriate measures taken shall be clearly indicated in the checklist.
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CP 88 : Part 1 : 2001
Annex A Statutory regulations and associated memoranda In the Republic of Singapore, temporary electrical installations are required to comply with the statutory regulations indicated below. The Regulations listed represent the principal legal requirements. Information concerning those regulations may be obtained from the appropriate authority also indicated below. (i)
Public Utilities Act
Public Utilities Board
(ii)
Public Utilities (Electricity) Regulations
Public Utilities Board
(iii)
Public Utilities (Electricity Supply) Regulations
Public Utilities Board
(iv)
Public Utilities (Licence To Use or Operate Electrical or Supply Installations) Regulations
Public Utilities Board
(v)
Electrical Workers and Contractors Licensing Act
Public Utilities Board
(vi)
Factories Act (Chapter 104)
Occupational Safety Dept Ministry of Manpower
(vii)
Factories (Building Operations and Works of Engineering Construction) Regulations
Occupational Safety Dept Ministry of Manpower
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CP 88 : Part 1 : 2001
Annex B Protective conductor proving and earth monitoring systems The use of flexible cables to supply power at mains voltages to moveable plant introduces special safety problems in ensuring the continuing efficiency of the earth return path. If the circuit protective conductor incorporated in the cable becomes damaged or discontinuous, it will no longer provide a sound metallic return path for the fault current should an earth fault occur. Earth monitoring and/or protective conductor proving may be employed to alleviate this situation.
B.1
Protective conductor proving system
A protective conductor proving system provides a means of establishing a degree of confidence in the continuity of the protective conductor from the proving unit to remote protected apparatus. No provision is made for impedance measuring but designs centred around the use of specialised relays afford a coarse method of proving. The proving unit may be connected anywhere between the origin of the installation and the apparatus to be protected. Detection of short circuits between pilot and protective conductors may be achieved by the use of d.c. sensitive relays as a part of the proving system. Continuity may be proved with a shunt connected voltage sensing device or a series connected current sensing device. In either case the protective conductor should be a substantial earth path of low impedance. The impedance of the source and detector combination Z1 (see figure B1) should appear in series with the pilot earth path. The total impedance of the monitored loop is the algebraic sum of the impedance Z1 and the impedance of the rest of the loop Z2. A value Z2 in excess of about 10 Ω should prevent the load apparatus being energised. Furthermore, after the apparatus has been energised, if the monitored loop becomes open-circuited or increases in impedance beyond about 20 Ω the apparatus should become isolated. NOTE – The impedance values quoted are only examples and the actual values need to be considered in the light of specific applications.
The proving current circulates in a loop circuit which contains the protective conductor to the apparatus, a section of the apparatus casing and a suitable return path. It is essential that any plug and socket and flexible cable therefore provide not only the main protective path but also a return path which is usually known as a pilot conductor. It is essential that the proving unit itself be properly earthed in accordance with SS CP 16. The fact that the earth loop contains a section of the apparatus casing, necessitates the provision of the two independent earth terminals on the casing, otherwise there would be a risk of both conductors becoming detached from the casing whilst still maintaining the monitored loop. It is worth noting that although the main and pilot paths are monitored in series, they function in parallel as far as actual earth-fault currents are concerned.
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CP 88 : Part 1 : 2001
B.2
Earth monitoring system
An earth monitoring system provides a means of maintaining a high degree of confidence in the impedance level of the protective conductor from the monitoring unit to the remote protected apparatus. The monitoring unit may be connected between the source of energy (if accessible) and the apparatus to be protected. NOTE – The source of energy may be, for example, a generator or a transformer.
Earth monitoring depends upon continuous circulation of a small current at a voltage not exceeding 12 V derived from a safety extra low voltage source. An interruption of this current is arranged to bring about disconnection of the protected apparatus from the supply. The monitoring current circulates in a loop circuit which contains the protective conductor to the apparatus, a section of the equipment casing and a suitable return path. It is therefore essential that any plug and socket and flexible cable provide not only the main protective path but also a return path which is usually known as the pilot conductor. It is worth noting that although the main and pilot paths are monitored in series, they function in parallel as far as actual earth-fault currents are concerned. It is essential that the monitoring unit be earthed in accordance with SS CP 16. The fact that the earth loop contains a section of the apparatus casing, necessitates the provision of two independent earth terminals on the casing, otherwise there would be a risk of both conductors becoming detached from the casing whilst still maintaining the monitored loop. The impedance of the protective and pilot conductors forms part of a balanced bridge network (see figure B2). The balance is disturbed by variations in the parameters of the loop (e.g. open circuit or short circuit) and this can initiate a signal or disconnection. Typical impedance sensitivity of the balanced bridge network (in the temperature range -10oC to +4oC) is 8 Ω ± 2 Ω. NOTE – Further information on earth monitoring and protective conductor proving is given in BS 4444.
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CP 88 : Part 1 : 2001
ORIGIN Proving Unit L
Apparatus
L
L
Supply terminals
Load terminals
N
N
L
N
N
Z1
V V S S
E2
E1
E
E
Z2 Diode (optional) P
P
Key
E1 E2 P S V
Z1 Z2
Protective earth terminal Earth terminal for pilot circuit (this may be internal or external) Pilot conductor terminal Sensing device Extra low voltage source Impedance of source Impedance of the loops
NOTE – If a diode is not used then a link has to be provided for a direct connection between terminals P and E2.
Figure B1 – Basic circuit for protective conductor proving unit
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CP 88 : Part 1 : 2001
ORIGIN Monitoring Unit L
L
Apparatus L
L
Supply terminals
Load terminals
N
N
N
N E
E B
E2
E1 Z2
Z1
Diode P
P
Key
B E1 E2 P
Z1 Z2
Balancing sensing network Protective earth terminal Earth terminal for pilot circuit (this may be internal or external) Pilot conductor terminal Impedance of source Impedance of the loops
Figure B2 – Basic circuit for earth monitoring unit
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CP 88 : Part 1 : 2001
Annex C Temporary electrical installations inspection checklist for construction and building sites Site :
__
_______
Date of inspection :
_____________
Installation Licence No : (1)
_______
________
____
Expiry Date : _____________
SINGLE LINE DRAWINGS (Minimum A3 size) Drawing No(s) _________________________________ submitted previously on _______________________ is/are still valid. New drawing which shows details of loads and circuits are enclosed. Drawing No. ___________________________________________
(2)
POWER SOURCE From public electricity supply system: Approved load =
____________________ KVA
Incoming circuit breaker rating =
____________________ A
From Generating Set: Details of generating sets are as follows: Particulars
Gen Set 1
Gen Set 2
Gen Set 3
Serial No. Supply Voltage (V)
Phase to Phase Phase to Earth
Rated KVA Power Factor Frequency (Hz) Fuel Used Mains Circuit Breaker Rating (A)
(3)
DISTRIBUTION VOLTAGES USED (tick accordingly) 400 V 3∅,
230 V single ∅,
110 V single ∅,
55 V single ∅
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Gen Set 4
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CP 88 : Part 1 : 2001
(4)
EARTHING ARRANGEMENT C
(5)
4.1
For double-wound 110V 1∅ transformer, centre tap of secondary winding is earthed.
4.2
The type of earthing system for electrical installation supplied from generating set, is TN-S.
4.3
Main earthing terminal or bar is adequately sized and properly installed.
4.4
Earth inspection chamber is accessible for inspection.
4.5
Bonding of metallic parts, where applicable, is adequate.
GENERATING SET 5.1
Barricaded to prevent access by non-authorised persons.
5.2
Adequate working space around generating set.
5.3
Access to generating set not impeded.
5.4
Generating set not installed in damp or exposed conditions.
5.5
Generating set not installed in hazardous location.
5.6
All live parts protected against direct contact.
5.7
Adequately sized earthing bar or terminal is provided.
5.8
Proper labelling of earthing conductors provided.
5.9
For 3∅ generator > 55 V, star-point is earthed.
5.10 For 1∅ generator > 55 V, neutral is earthed. 5.11 Engine frame and generator frame bonded to earth. 5.12 Bonding of metallic parts, where applicable, is adequate. 5.13 All outgoing supply cables provided with overcurrent and earth fault protection. 5.14 Protective devices are in operating condition. (6)
MAINS INCOMING SUPPLY AND EARTH LEAKAGE PROTECTION 6.1
For incoming supply ≤ 300 A 3∅, a circuit breaker with residual current device is used.
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Compliance NC NA
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CP 88 : Part 1 : 2001
C
(7)
(8)
6.2
For incoming supply > 300 A 3∅, a circuit breaker with overcurrent and earth protective devices are used.
6.3
Residual current circuit breaker with tripping current ≥ 100 mA operates within 0.1 s at rated tripping current.
6.4
Earth fault loop impedance is tested for satisfactory operation against indirect contact.
6.5 (a) (b) (c) (d)
Overall insulation resistance ≥ 0.5 MΩ phase to phase, phase to earth, phase to neutral, neutral to earth.
6.6
Earthing conductor is appropriately sized and properly terminated.
6.7
Warning signs are displayed at main generating set and main intake switchboard.
Compliance NC NA
As amended May 2001
DISTRIBUTION BOARD (DB) 7.1
DB is properly installed and earthed.
7.2
Submains cables are properly terminated and installed.
7.3
DB is properly labelled.
7.4
Good protective conductor continuity.
7.5
Warning signs are displayed at distribution boards.
7.6
All outdoor cables are of armoured construction.
7.7
No metal sheath or armour of any cable is used as circuit protective conductor.
FINAL CIRCUITS 8.1
For final circuits ≤ 63 A, RCCB with tripping current ≤ 30 mA operates within 0.1 s.
8.2
For final circuits exceeding 63 A but not exceeding 100A, RCCB with tripping current ≤ 300 mA operates within 0.1s.
8.3
For final circuits > 100A, a RCD with tripping current not exceeding 500mA is provided.
8.4
Insulation resistance to earth of each final circuit ≥ 1 MΩ.
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CP 88 : Part 1 : 2001
C 8.5
Polarity at all socket-outlets is correct.
8.6
All flexible cords, switches, plugs and socket outlets are in good and serviceable condition.
8.7
Rewireable fuses are not used except for socket-outlet incorporated with fuses.
8.8
All switches for 1∅ supply ≤ 110 V shall be of doublepole type with protection in each live conductor.
8.9
Colour codes of plug, socket-outlet and cable coupler of different operating voltages are correct.
8.10 All cables are properly supported. 8.11 Circuit protective conductor is provided for each final circuit. 8.12 No flexible cord is used as fixed wiring. (9)
(10)
SOCKET-OUTLET ASSEMBLY 9.1
Socket-outlet assembly is properly installed and earthed.
9.2
Socket-outlet assembly is the recommended type.
9.3
Incoming is a fixed plug (male)
9.4
Outgoing outlets are fixed sockets
9.5
Each fixed socket-outlet protected by approved type residual current circuit breaker (RCCB), current rating not exceeding 30 mA and a MCB.
ENVIRONMENTAL CONDITIONS 10.1 Unimpeded access to the main switchboard 10.2 Switchroom locking facilities are provided 10.3 Switchroom shows no sign of water leakage or seepage 10.4 Lighting for switchboard is adequate 10.5 Switchroom ventilation is adequate 10.6 Switchroom is not used for storage 10.7 Switchroom free of vermin and rodents
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Compliance NC NA
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CP 88 : Part 1 : 2001 (11)
GENERAL OBSERVATIONS
Tick accordingly: C NC NA
(12)
– – –
Comply Non Comply Not Applicable
DECLARATION BY LICENCE ELECTRICAL WORKER (SKILLED PERSON)
I declare that the electrical installation is * fit and safe / unfit and unsafe for operation. * Please delete as appropriate.
Name of LEW : _________________________________
Licence No :
Signature :
Date :
_________________________________
The inspection was witnessed by owner / operator of the electrical installation. Name of Representative : Designation : Signature :
Date :
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CP 88 : Part 1 : 2001
Annex D As amended May 2001
Danger signboard
400mm
280mm NOTE – The danger signboard shall have the word ‘DANGER’ and the operating voltage of the equipment inscribed: (a) (b) (c) (d)
In block characters of at least 30 mm high and 5mm wide; and In the English, Malay, Chinese and Tamil languages; and In black against a yellow background; and Be maintained in a clear and legible condition at all times.
It is recommended that the dimensions of the signboard be at least 280mm x 400mm.
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CP 88 : Part 1 : 2001
Annex E Clauses that are extracted from British standards Clause no.
Clause Title
British Standard
BS Clause no./Title
2.2
Earth monitoring system
BS 4444 : 1989
2.2 – Earth monitoring system
2.8
Site
BS 4363 : 1998
2.1 – Site
BS 7375 : 1996
3.5.1 – Electrical protection of circuit. General
3.1.2.2
Supply voltage generating sets
from
4.1.3
Protection of circuits
BS 7375 : 1996
3.5.1 – Electrical protection of circuit. General
4.3.5
Protective conductor proving and earth monitoring systems
BS 7375 : 1996
3.5.5 – Protection conductor proving and earth monitoring systems
Annex B
Protective conductor proving and earth monitoring systems
BS 4444 : 1989
3 – Earth proving systems 4 – Earth Monitoring system
BS 7375 : 1996
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3.5.5.1 to 3.5.5.3
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CP 88 : Part 1 : 2001
Standards referred to: AS 2790 : 1989
Electricity generating sets – Transportable (Up to 25 kW)
AS 3010.1 : 1987
Electrical installations – Supply by generating set Part 1 – Internal combustion engine driven set
BS 4363 : 1998
Specification for distribution assemblies for reduced low voltage electricity supplies for construction and building sites
BS 4444 : 1989
Guide to electrical earth monitoring and protective conductor proving
BS 5345 : -
Code of Practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmosphere (other than mining applications or explosive processing and manufacture)
BS 6500 : 2000
Specification for electric cables – Flexible cords rated up to 300/500 V, for use with appliances and equipment intended for domestic, office and similar environments
BS 6708 : 1998
Flexible cables for use at mines and quarries
BS 7375 : 1996
Code of practice for distribution of electricity on construction and building sites
BS EN 60898 : 1991
Specification for circuit breakers for overcurrent protection for household and similar installations
IEC 60245-1 : 1994
Rubber insulated cables – Rated voltages up to and including 450/750V Part 1 – General requirements
IEC 60309-2 : 1999
Plugs, socket outlets and couplers for industrial purposes Part 2 – Dimensional interchangeability requirements for pin and contact-tube accessories
SS CP 5 : 1998
Code of Practice for Electrical Installations
SS CP 16 : 1991
Code of practice for Earthing
SS CP 31 : 1996
Code of practice for Installation, operation, maintenance, performance and constructional requirements of mains failure standby generating systems
SS CP 33 : 1996
Code of practice for lightning protection
SS 97 : Part 1 : 2000
Specification for Residual Current Circuit Breakers without Integral Overcurrent Protection for Household and Similar Uses (RCCB’s) Part 1 – General rules
SS 145 : Part 1 : 1997 Specification for 13A plugs and socket outlets Part 1 – Rewirable and non-wirable 13A fused plugs SS 145 : Part 2 : 1997 Specification for 13A plugs and socket outlets Part 2 – 13A switched and unswitched socket-outlets SS 358 : Part 5 : 1998 Specification for Polyvinyl chloride insulated cables of rated voltages up to and including 450/750V Part 5 – Flexible cords
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CP 88 : Part 1 : 2001 SS 359 : 1996
Specification for Circuit breakers for overcurrent protection for household and similar installations
SS 443 : Part 1 : 1998 Specification for Power cables with extruded insulation and their accessories for rated voltages from 1 kV (Um=1.2 kV) up to 30 kV (Um = 36 kV) Part 1 – Cables for rated voltages of 1 kV (Um = 1.2 kV) and 3 kV (Um = 3.6 kV) SS IEC 60529 : 1989
Specification for Degrees of protection provided by enclosures (IP Code)
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CP 88 : Part 1 : 2001 ABOUT SPRING SINGAPORE SPRING Singapore is an agency under the Ministry of Trade and Industry responsible for helping Singapore enterprises grow and building trust in Singapore products and services. As the national standards and accreditation body, SPRING develops and promotes an internationally-recognised standards and quality assurance infrastructure. SPRING also oversees the safety of general consumer goods in Singapore. As the enterprise development agency, SPRING works with partners to help enterprises in financing, capability and management development, technology and innovation, and access to markets. SPRING Singapore 1 Fusionopolis Walk #01-02 South Tower, Solaris Singapore 138628 Tel: 6278 6666 Fax: 6278 6667 E-mail:
[email protected] Website: http://www.spring.gov.sg
ABOUT THE NATIONAL STANDARDISATION PROGRAMME Under the national standardisation programme, SPRING Singapore helps companies and industry to meet international standards and conformity requirements by creating awareness of the importance of standardisation to enhance competitiveness and improve productivity, co-ordinating the development and use of Singapore Standards and setting up an information infrastructure to educate companies and industry on the latest developments. SPRING Singapore is vested with the authority to appoint a Standards Council to advise on the preparation, publication and promulgation of Singapore Standards and Technical References and their implementation. Singapore Standards are in the form of specifications for materials and products, codes of practice, methods of test, nomenclature, services, etc. The respective committee or working group will draw up the standards before seeking final approval from the Standards Council or the relevant Standards Committee. To ensure adequate representation of all viewpoints in the preparation of Singapore Standards, all committees appointed consist of representatives from various interest groups which include government agencies, professional bodies, tertiary institutions and consumer, trade and manufacturing organisations. Technical References are transition documents developed to help meet urgent industry demand for specifications or requirements on a particular product, process or service in an area where there is an absence of reference standards. Unlike Singapore Standards, they are issued for comments over a period of two years before assessment on their suitability for approval as Singapore Standards. All comments are considered when a technical reference is reviewed at the end of two years to determine the feasibility of its transition to a Singapore Standard. Technical References can therefore become Singapore Standards after two years, continue as Technical References for further comments or be withdrawn. In the international arena, SPRING Singapore represents Singapore in the International Organisation of Standardisation (ISO), the Asia-Pacific Economic Co-operation (APEC) Sub-committee for Standards and Conformance (SCSC) and in the ASEAN Consultative Committee on Standards and Quality (ACCSQ). The Singapore National Committee of the International Electrotechnical Commission which is supported by SPRING Singapore, represents Singapore in the IEC.
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The Singapore Standardisation Programme is managed by
SPRING Singapore 1 Fusionopolis Walk, #01-02 South Tower, Solaris Singapore 138628 Tel : +65 6278 6666 Fax : +65 6278 6667 www.spring.gov.sg
