Electrical Installations in High Rise Buildings

Electrical Installations in High Rise Buildings & Energy Conservation Building Code (ECBC) Authors: V. K. Raheja, Chief Electrical Engineer, North Western Railway P. L. Meena, Dy. Chief Electrical Engineer, North Western Railway M. K. Goyal, Divisional Electrical Engineer, North Western Railway Abstract: The design & planning of an electrical installation involve consideration of all prevailing conditions and is usually guided by the requirement of the consumer. The various functional needs, efficiency, economy, energy conservation, aesthetics, technology, fire & life safety solution, access control, transportation of man & material, human comforts, operation & maintenance practices, provision of future growth are some of the main factors to be incorporated in the design at the planning stage by a competent electrical engineer. 1.0 Introduction Presently our country is witnessing the higher growth in infrastructure development mainly in urban areas and there is disproportionate transit of population towards cities, which has generated the need of vertical extension of offices/residential/commercial buildings looking to constraints of land and commutation from far locations to city hub. In addition environment is also affected with the destruction of God gifts such as mountains, forests, trees, rivers, potable water, and agriculture land etc. in its original shape/form. Therefore to maintain fast growth of development along with ecological balance, there is need of High Rise Building (A building above four stories, and/or a building exceeding 15 meter or more in height above the average level of front road). With the construction of high rise buildings issue of fire & life safety solution, access control, resource management with high level protection with human comforts and modern look arises and in turn it is a challenge to electrical engineers to give there best to the countrymen. 2.0 Main Electrical installations/systems Looking to present function need, electrical installations/systems are to be provided essentially in high-rise buildings incorporating all by laws and codes etc. may be divided in following system: A. Power house: Sub station, DG sets, HT/LT panes with high degree protection. B. Power supply distribution system: LT panel, Main Distribution Boards, Sub Distribution Boards, Distribution Boards, Switches. The connectivity of all these with accurate size of conductors using Rising Mains for vertical power distribution, Bus Trunking for Transformers and DG set interconnections C. Lighting system: Lux level as per standards Modern lighting technology based fixtures D. Water supply system: Pumping with auto control, stand by bore well, cold & hot water plants, suitable under ground/overhead water static tanks.

E. Air conditioning & Air cooling F. Lift G. Fire & life safety solution: Automatic Fire detection & alarm system, Fire fighting system, automatic sprinklers system, fire aid hose reels, fire extinguishers, illuminated exit way marking signs, Alternate source of electric supply, fire lift with fireman switch, Wet riser system, public address system H. Building Management/Automation System The brief of various systems is described as: A.

Power house:

(i) Need: Electrical sub station is required when electric load is in excess of permitted LT supply limit of Electrical Supply Authority or due to any other technical reason. (ii) Location: The ideal location would be at the load center on the ground floor in a separate building accessible through a motorable road the floor level of the sub station or switch room shall be above the highest flood level of the locality. Location of sub station in the basement should be avoided as far as possible on account of likely flooding and fire hazard. If unavoidable then anti flood measures such automatic dewatering pumping, waterproof basement, isolation from rest of basement, suitable fire detection/protection system to be provided with the approval of local fire authority. Stand by supply equipment shall not be allowed to be installed above ground floor or below first basement level of building. Provision of growth of electric load to be kept at the time of system and space design. (iii) Building: Provision of building to house HT /LT switchgear, metering, UPS, battery, switch room, vertical shaft for power, fire fighting/detection, wet risers, cable ducts, space for MDBs, SDBs, DBs, supervisor, store, staff be kept. (iii) Capacity & features: Whole different type load is divided into two type i.e. Essential load and non-essential load. The essential load shall be fed by stand by DG set in case Discom power supply fails. Instead of having two transformers i.e. one in service and another as standby number of transformers should be at least three out of that one or two should be on load depending on load through load manager (as load in night hours and winters shall be less) and remaining one should be used as standby. The main features of sub station shall be as under: a. Compact sub stations (CSS) with dry/oil type transformers of required capacities and protected through VCB on HT side and ACB/MCCBs on LT side, connected with required numbers & value copper plate earthings. b. Microprocessor based Load managers to control transformers for energy saving and reliability of system. When load on the system is less than particular limit then whole load will be taken by one transformer automatically thus saving of no load losses of one transformer and operating the other transformer efficiently, in case of failure of any of transformer the supply of that unit will be taken up by standby transformer automatically. c. Provision of Auto Power Factor Correction (APFC) panels with requisite capacity bank of capacitors. d. Bus trunking should be used to provide interconnections between transformers and DG sets. e. Standby supply through DG Sets. The DG set shall start automatically in case of Discom power supply failure.

f. The monitoring of transformers and DG sets through BMS system thus proper management of their operating and maintenance schedules. g. As per mandatory requirement ($8.2 of ECBC) maximum allowable power transformer losses with highest voltage for equipment 24kV, at 50%and 100% of the load should be less than the prescribed limit (table 8.2.1.1 & 8.2.1.2 of ECBC). All electricity supplies exceeding 100A, 3 phase shall maintain their power factor between 0.95 lag and unity at the point of connection ($8.2.3 of ECBC). Check metering and monitoring to be provided & done ($8.2.4 of ECBC). h. DG set noise level should be less than the limit prescribed by Central Pollution Control Board (CPCB). B. Power supply distribution system: Following main points to be taken care for proper distribution of power supply: a. Separate LT panel for essential & non-essential load should be provided. b. There should be separate rising mains for essential & non-essential supply system through bus bars and plug in unit floor wise to MDB to SDB to DB to SB, which is very reliable and modern system for vertical power supply system. c. Separate supply connection through MCCB with cables to the plants provided out side the building such as AC plants, pumps, fire fighting equipment, general lighting, lifts, service buildings etc. to be made with specific provision in main LT panel of essential and non-essential supply. d. Separate breaker (i.e. MCCB/MCB/HRC type) for incoming and out going circuits to be used. Rewirable type fuses shall not be used. Three phase DBs shall not be used for final circuit distribution as far as possible and power wiring shall be kept separate from point wiring. e. Rating of breakers, wires, points, socket outlets shall be standard. f. Proper colour coding shall be followed i.e. Phase- Red/Yellow/Blue (three phase wiring), Live-Red (single phase wiring), Neutral-Black, Earth-Green/Yellow. g. After office hours all LT panels should be switched off. Only supply of emergency areas such as specific lift, staircase/corridor/compound lights, fire protection board, pumps, server/computer room, security lights may be kept on. h. PVC trunking shall be adopted in buildings where there is a need of tidy wiring system. i. Earth continuity should be ensured for all metallic boxes and earth pin of socket out lets. j. Degree of protection required for outdoor/indoor cubicles shall be ensured. k. Earth value should be maintained as prescribed in IE Rules for different equipment/installations. l. Detailed instructions on safety procedures as per I E Rules and BIS code no.52161982 shall be followed strictly. Non-compliance to should be got rectified immediately. m. All tests such as insulation resistance test, polarity test of switch, earth continuity test, earth electrode resistance test shall be done, witnessed & recorded and kept for record. n. Power supply network system should be adequately sized and distribution losses not to exceed 1% of the total power usage ($8.2.5.1 of ECBC).

C. (i)

Lighting system Recommended Lux level as per BIS: 3646(part-II)

Sr. Location Lux No. 1. Corridors and lift cars, garages 70 2 Shelves, stacks 100 3 Stairs 100 4 Entrance hall and reception areas 150 5 Lift landing 150 6 Telephone exchange main distribution frame room 150 7 Assembly hall-general 150 8 Staff room, common room 150 9. Circulating area/lounges 150 10 Telephone exchange manual exchange room 200 11 Conference/class room, executive/general/drawing offices 300 12 Assembly hall/platform when used for examination 300 13 Laboratories, library reading table 300 14 Business machine operation, boards & tracing, art room 450 (ii) Provisions as per ECBC 1.0 General: Lighting systems and equipments shall comply with the mandatory provisions of $7.2 and prescriptive criteria of $7.3 & $7.4 and apply to (i) Interior spaces of buildings (ii) Exterior building features (iii) Exterior building ground lighting. Exceptions are (i) Emergency lights that is powered through alternate power source and (ii) Lighting in dwelling units 2.0 Mandatory requirement ($7.2) 2.1 Lighting Control ($7.2.1) 2.1.1 Automatic lighting shutoff($7.2.1.1): Through automatic control device equipped with occupancy sensors for interior lighting system in buildings larger than 500 m2. For other spaces, this automatic control device shall function on either (i) A scheduled basis at specific programmed times independently program scheduled for area not more than 2500m2 and not more than one floor or (ii) Through occupancy sensors turn off within 30” of an occupant leaving space and shall have wall mounted manual switch to turn off light fixtures. Exception is lighting systems designed for 24 hours use. 2.1.2 Space Control: At least one control manual or automatic for space enclosed by ceiling-height partitions. Each control device shall: (i) control a maximum 250m2 for a space less than or equal to 1000m2 and a maximum of 1000 m2 for a space greater than 1000 m2. (ii) Be capable of overriding the shutoff control required in 7.2.1.1 for no more than 2 hours, and (iii) Be readily accessible and located so the occupants can see the control. 2.1.3 Control in Day lighted Areas: Light fixtures provided in area greater than 25 m2 shall be equipped with manual or automatic control device that: can reduce the light output in day lighted area by at least 50%, and (ii) controls only the luminaries located entirely within the day lighted area. 2.1.4 Exterior lighting control: Lighting of all exterior applications shall be controlled by a photo sensor or astronomical time switch. 2.1.5 Additional control: Independent control device shall be provided for the lighting applications (i) Display/Accent/Case lighting in area greater than 300 m2.

(ii) Main control at the entry of main room for hotel/motel guest rooms/suites. (iii) Task lighting including permanently installed under shelf/cabinet should have integrated control with luminaries or be controlled by a wall mounted control device. (iv) Non visual lighting (v) Demonstration lighting 2.2 Exit signs ($7.2.2): Internally illuminated exit sign shall not exceed 5W per face. 2.3 Exterior building grounds lighting ($7.2.3): Luminaries of more than 100 W should have minimum efficacy of 60 lm/W. 3.0 Interior lighting power ($7.3,$7.3.3): Calculation shall include all power used by luminaries including lamp, ballasts, regulators and control devices. Exceptions are lighting for display/accent/demonstration light essential element for function performance, integral to equipment/instrument as per manufacturer, medical/dental procedure, food warming/preparation equipment, plant growth/maintenance, visually inspired, historic landmark display, signage, theatrical purpose, athletic playing area & television broadcasting. 3.1 Determination of interior lighting power allowance (W) 3.1.1 Building Area Method ($7.3.1 and table 7.3.1): Interior Lighting Power allowance is the sum of the product of Allowed Lighting Power Density (LPD) X gross lighted area. Determine LPD (W/m2) as per table 7.3.1, for office=10.8, dinning/family=17.2, dormitory=10.8, hospital=12.9, workshop=15.1, parking garage=3.2. 3.1.2 Space Function Method ($7.3.2): Interior Lighting Power Allowance is the sum of the lighting power allowances of all spaces. Allowed lighting power density for appropriate building type is determined by table 7.3.2.For each space enclosed by partitions 80% or greater than ceiling height determine the gross interior floor area by measuring to the center of the partition wall Include the floor area of balconies. For office=11.8, conference=14.0, dining/family=22.6, dormitory=11.8, hospital=10.8, workshop=20.5, parking garage=2.2. 3.1.3 Luminaire wattage: If not containing permanently installed ballast then labelled wattage otherwise operating input wattage of the specified lamp/ballast combination values as per manufacturer or test report. For type not described above as per specified wattage of Luminaire. Wattage for flexible lighting system, to be taken as per larger of specified wattage or 135W/m. 4.0 Exterior Lighting Power ($7.4): Shall not exceed as specified in table 7.4. Building entrance (with canopy) =13 W/m2 of canopied area, Building entrance (without canopy)=90 W/lin m of door width, Building exit=60 W/lin m of door width, Building facades=2 W/m2 of vertical façade area. Exceptions are independently controlled lighting for the application of transportation lighting/signals, monuments, historic landmark structures/buildings, signage, health or life safety, statute, ordinance, or regulation. (iii) Features of lighting arrangement inside the building: a. Use of occupancy sensors in rooms and corridors to have automatic control of ON/OFF of lighting. b. Use of energy efficient and better interiors lights adding good aesthetic view for building. c. The energy meters to be provided to record section wise energy consumption and to send the details to a centralised system through BMS. Using this, energy use of different sections can be monitored and information can be send to conserve electricity for a particular section if energy use of that section is found more than a limit.

d. Concealed wiring with modular switches and distribution boxes with glass cover to be used to give a better view. e. LED signage with changing colours to be used. f. Decorative CI heritage look outer poles to be used for pathway and garden lighting. g. Automatic control of lights through Lux sensor. h. Only energy efficient light such as LED, CFL, T5 to be used. i. Solar cell module of capacity 10 to 15 kW to be installed at the top of building to meet with the emergency load. j. Maximum use of daylight. D. Water supply system & cold water system: Complete monitoring and control of all pumps in the building and their associated system, water level in overhead or underground tank by level switches and ensure switching ON /OFF the pumps automatically with integrating the water supply system with BMS. Modular type water coolers to be provided and fixed on wall, requiring no space on floor, no spillage of water in and around the machine, in addition to good esthetic look. Since cooling coils are directly in touch of water therefore high efficiency and result into energy conservation. No problem of corrosion as no accumulation of water on the body of machine. For hot water requirement 20 % hot water requirement shall be met from solar heat/heat recovery and not more than 80% of heat shall be met from electrical heating. Where gas is available not more than 20% of the heat shall be met from electrical heating ($ 6.2.1 to 6.2.7 of ECBC). E. HVAC and Air-cooling System: 1.0 HVAC system 1.1 Provisions as per ECBC ($5.2.1 to $5.2.6, $ 5.3.1and $5.3.2) 1.1.1 Natural ventilation shall comply with the design guidelines as per NBC of India 2005. 1.1.2 Cooling equipment shall meet or exceed the minimum efficiency as per table 5.2.2-1 to 5.2.2-5 and heating/cooling equipment shall comply with ASHRAE 90.1-2004 $6.4.1, Room AC, Split AC, Packaged AC shall meet the relevant IS. 1.1.3 All mechanical cooling & heating systems shall be controlled by a time clock that can start/stop system under different schedule for 3 different day-types per week, can retain programming & time setting during loss of power for a period of at least 10 hours, and capable of manual override operations temporary up to 02 hours. Exceptions are cooling system