Electrical Abstract- NBC- (Part-2)
Luminous Efficacy, Lumen Maintenance and Color Rendition (Table-8) NBC | |||||
| Light Source | Wattage | Efficacy (lm/W ) | Average Life | Maintenance | Color Rendition |
| Incandescent lamps | 15 to 200 | 12 to 20 | 500 to 1000 | Fair to good | Very good |
| Tungsten halogen | 300 to 1500 | 20 to 27 | 200 to 2000 | Good to very good | Very good |
| Standard fluorescent lamps | 20 to 80 | 55 to 65 | 5000 | Fair to good | Good |
| Compact fluorescent lamps (CFL) | 5 to 40 | 60 to 70 | 7500 | Good | Good to very good |
| Slim line fluorescent | 18 to 58 | 57 to 67 | 5000 | Fair to good | Good |
| High pressure mercury vapor lamps | 60 to 1000 | 50 to 65 | 5000 | Very low to fair | Federate |
| Blended – light lamps | 160 to 250 | 20 to 30 | 5000 | Low to fair | Federate |
| High pressure sodium vapor lamps | 50 to 1000 | 90 to 125 | 10000 to 15000 | Fair to good | Low to good |
| Metal halide lamps | 35 to 2000 | 80 to 95 | 4000 to 10000 | Very low | Very good |
| Low pressure sodium | 10 to 180 | 100 to 200 | 10000 to 20000 | Good to very good | Poor |
| LED | 0.5 to 2.0 | 60 to 100 | 10000 | Very good | Good for white LED |
Approximate Cable Current Capacity | ||
| Cable Size | Current Capacity | MCB Size |
| 1.5 Sq.mm | 7.5 To 16 A | 8A |
| 2.5 Sq.mm | 16 To 22 A | 15A |
| 4 Sq.mm | 22 To 30 A | 20A |
| 6 Sq.mm | 39 To 39 A | 30A |
| 10 Sq.mm | 39 To 54A | 40A |
| 16 Sq.mm | 54 To 72A | 60A |
| 25 Sq.mm | 72 To 93A | 80A |
| 50 Sq.mm | 117 To 147A | 125A |
| 70 Sq.mm | 147 To 180A | 150A |
| 95 Sq.mm | 180 To 216A | 200A |
| 120 Sq.mm | 216 To 250A | 225A |
| 150 Sq.mm | 250 To 287A | 275A |
| 185 Sq.mm | 287 To 334A | 300A |
| 240 Sq.mm | 334 To 400A | 350A |
Requirements for Physical Protection of Underground Cables (As per NBC) | |
| Protective Element | Specifications |
| Bricks | (a) 100 mm minimum width |
| (b) 25 mm thick | |
| (c) sand cushioning 100 mm and sand cover 100 mm | |
| Concrete slabs | At least 50 mm thick |
| Plastic slabs (polymeric cover strips) Fiber reinforced plastic | depending on properties and has to be matched with the protective cushioning and cover |
| PVC conduit or PVC pipe or stoneware pipe or Hume pipe | The pipe diameter should be such so that the cable is able to easily slip down the pipe |
| Galvanized pipe | The pipe diameter should be such so that the cable is able to easily slip down the pipe |
| The Trench : The trench shall be back filled to cover the cable initially by 200 mm of sand fill; and then a plastic marker strip hall be put over the full length of cable in the trench. | |
| The Marker Signs: The marker signs shall be provided where any cable enters or leaves a building. This will identify that there is a cable located underground near the building. | |
| The trench shall then be completely filled. If the cables rise above ground to enter a building or other structure, a mechanical protection such as a GI pipe or PVC pipe for the cable from the trench depth to a height of 2.0 m above ground shall be provided. | |
AREA REQUIRED FOR GENERATOR IN ELECTRIC SUBSTATION (As per NBC) | ||
| Capacity kVA | Area m2 | Clear Height below the Soffit of the Beam m |
| 25 | 56 | 3.6 |
| 48 | 56 | 3.6 |
| 100 | 65 | 3.6 |
| 150 | 72 | 3.6 |
| 248 | 100 | 4.2 |
| 350 | 100 | 4.2 |
| 480 | 100 | 4.2 |
| 600 | 110 | 4.6 |
| 800 | 120 | 4.6 |
| 1010 | 120 | 6.5 |
| 1250 | 120 | 6.5 |
| 1600 | 150 | 6.5 |
| 2000 | 150 | 6.5 |
Low Voltage Cabling for Building (As per NBC) | |
| Low Voltage Cable | Cables/wires, such as fiber optic cable, co-axial cable, etc. These shall be laid at least at a distance of 300 mm from any power wire or cable. The distance may be reduced only by using completely closed earthed metal trucking with metal separations for various kind of cable. Special care shall be taken to ensure that the conduit runs and wiring are laid properly for low voltage signal to flow through it. |
| The power cable and the signal or data cable may run together under floor and near the equipment. However, separation may be required from the insulation aspect, if the signal cable is running close to an un-insulated conductor carrying power at high voltage. All types of signal cables are required to have insulation level for withstanding 2 kV impulse voltages even if they are meant for service at low voltage. | |
| Conduit Color Scheme | Power conduit=Black Security conduit=Blue Fire alarm conduit=Red Low voltage conduit=Brown UPS conduit Green |
Sub Station Guideline (As per NBC) | |
| Substation Location | Location of substation in the basement should be avoided, as far as possible. |
| If there is only one basement in a building, the substation/switch room shall not be provided in the basement and the floor level of the substation shall not be lowest point of the basement. | |
| Substation shall not be located immediately above or below plumbing water tanks or sewage treatment plant (STP) water tanks at the same location | |
| Substation Door/Shutter | All door openings from substation, electrical rooms, etc, should open outwards |
| Vertical shutters (like rolling shutters) may also be acceptable provided they are combined with a single leaf door opening outwards for exit in case of emergency | |
| For large substation room/electrical room having multiple equipment, two or more doors shall be provided which shall be remotely located from each other | |
| No services or ventilation shafts shall open into substation or switch room unless specific to substation or switch room | |
| Transformer Location | In case of HV panel and transformers located at different floors or at a distance more than 20 m, HV isolator shall be provided at transformer end |
| In case transformer and main MV/LV panel room are located at different floors or are at a distance more than 20 m, MV/LV isolator shall be provided at transformer end | |
| In case of two transformers (dry type or transformers with oil quantity less than 2 000 liter) located next to each other without intermittent wall, the distance between the two shall be minimum 1 500 mm for 11 kV, minimum 2 000 mm for 22 kV and minimum 2 500 mm for 33 kV. Beyond 33 kV, two transformers shall be separated by baffle wall of 4 h fire rating. | |
| If dry type transformer is used, it may be located adjacent to medium voltage switch gear in the form of unit type substation. In such a case, no separate room or fire barrier for the transformer is required either between transformers or between transformer and the switch gear, thereby decreasing the room space requirement; however, minimum distances as specified. | |
| Oil Filled Equipment (Transformer / C.B) | Substations with oil-filled equipment/apparatus transformers and high voltage panels shall be either located in open or in a utility building |
| They shall not be located in any floor other than the ground floor or the first basement of a utility building not be located below first basement slab of utility building. | |
| They shall have direct access from outside the building for operation and maintenance of the equipment. | |
| It shall be separated from the adjoining buildings including the main building by at least 6 m clear distance to allow passage of fire tender between the substation/utility building and adjoining building/main building. | |
| Substation equipment having more than 2 000 liter of oil whether located indoors in the utility building or outdoors shall have baffle walls of 4 h fire rating between apparatus. | |
| Provision of suitable oil soak-pit, and where use of more than 9 000 liter of oil in any one oil tank, receptacle or chamber is involved, provision shall be made for the draining away or removal of any oil which may leak or escape from the tank, receptacle or chamber containing the same | |
| Power Supply Voltage | supply is at 240 V single phase up to 5 kVA, 415/240 V 3-phase from 5 kVA to 100 kVA, 11 kV (or 22 kV) for loads up to 5 MVA and 33 kV or 66 kV for consumers of connected load or contract demand more than 5 MVA. |
| In case of connected load of 100 kVA and above, the relative advantage of high voltage three-phase supply should be considered. | |
| In case of single point high voltage metering, energy meters shall be installed in building premise,such a place which is readily accessible to the owner/operator of the building and the Authority. The supplier or owner of the installation shall provide at the point of commencement of supply a suitable isolating device fixed in a conspicuous position at not more than 1.7 m above the ground so as to completely isolate the supply to the building in case of emergency | |
| Trench Drain | In case of cable trench in substation/HV switch room/MV switch room, the same shall be adequately drained to ensure no water is stagnated at any time with live cables. |
| Fence for Substation | Enclose any part of the substation which is open to the air, with a fence (earthed efficiently at both ends) or wall not less than 1800 mm (preferably not less than 2400 mm) in height |
| HV Distribution in Building | The power supply HV cables voltage shall not be more than 12 kV and a separate dedicated and fire compartmented shaft should be provided for carrying such high voltage cables to upper floors in a building. These shall not be mixed with any other shaft and suitable fire detection and suppression measures shall be provided throughout the length of the cable on each floor. |
| Switch Room / MV switch room | Switch room / MV switch room shall be arrived at considering 1200 mm clearance requirement from top of the equipment to the below of the soffit of the beam .In case cable entry/exit is from above the equipment (transformer, HV switchgear, MV switchgear), height of substation room/HV switch room/MV switch room shall also take into account requirement of space for turning radius of cable above the equipment height. |
Area for Transformer Room: (As per NBC-2005):
| Transformer Size | Min. Transformer Room Area (M2) | Min. Total Sub Station Area( Incoming HV,LV Panel, T.C Roof) (M2) | Min. Space Width (Meter) |
| 1X160 | 14 | 90 | 9 |
| 2X160 | 28 | 118 | 13.5 |
| 1X250 | 15 | 91 | 9 |
| 2X250 | 30 | 121 | 13.5 |
| 1X400 | 16.5 | 93 | 9 |
| 2X400 | 33 | 125 | 13.5 |
| 3X400 | 49.5 | 167 | 18 |
| 2X500 | 36 | 130 | 14.5 |
| 3X500 | 54 | 172 | 19 |
| 2X630 | 36 | 132 | 14.5 |
| 3X630 | 54 | 176 | 19 |
| 2X800 | 39 | 135 | 14.5 |
| 3X800 | 58 | 181 | 14 |
| 2X1000 | 39 | 149 | 14.5 |
| 3X1000 | 58 | 197 | 19 |
- The Capacitor Bank should be automatic Switched type for Sub Station of 5MVA and Higher.
- Transformer up to 25KVA can be mounted direct on Pole.
- Transformer from 25KVA to 250KVA can be mounted either on “H” Frame of Plinth.
- Transformer above 250KVA can be mounted Plinth only.
- Transformer above 100MVA shall be protected by Drop out Fuse or Circuit Breaker.