LIGHTING
LIGHTING DESIGN GUIDE (TCE-M6-EL-GL-G-815-6300R2)
1.0 Colour rendering Incandescent - 100
Halogen - 100
Fluorescent - 80-85
Metal halide - 80-90
Warm white fluorescent - 56
HPMV - 48
HPSV - 30
LPSV - <25
2.0 Mounting heights Fluorescent - up to 5m
Low bay fixtures - 5m – 6m
Medium bay fixtures - 6m – 9m
High bay fixtures - >9m
3.0 Reflection factors White & very light colors- 0.7
Light colors - 0.5
Middle tints - 0.3
Dark colors - 0.1
4.0 Ht. of working plane Office rooms - 0.75
Other areas - 0.85
5.0 Maintenance factors Air-conditioned areas - 0.80
Clean areas - 0.75
Industrial areas (normal)- 0.70
Industrial areas (dusty) - 0.60
Industrial areas (very dusty)- 0.50
For outdoor areas - 0.5 to 0.8
0.6 for average conditions
6.0 Indoor lighting N = EAV X S Where,
LUM X n X d
N = No. of luminares.
Eav = Illuminance.
S = Area of the room M2.
d = Maintenance factor.
LUM = Lumen output of the lamp.
n = Coefficient of utilisation.
K = L X W where
Hm(L+W)
K = Room index.( Generally varies between 0.6 to 5.0.
Whenever L>5W, it shall be considered as L = 5W)
L&W = Length & Width of the room.
Hm = Height of working plane.
7.0 Outdoor lighting S = LUM X n x d Where,
EAV X W
S = Spacing between luminaries.
Eav = I luminance.
W = Width of the road.
d = Maintenance factor.
LUM = Lumen output of the lamp.
n = Coefficient of utilization.
= 0.25 to 0.6
= 0.30 for 80/125W HPMV and for 70W HPSV
lamps.
= 0.45 for HPMV/HPSV lamps of higher wattages.
Mounting height of streetlights varies between 7.7m to 11m.
Ratio of spacing to mounting height shall not exceed 3.0 for cut off type luminaries and 3.5 times
for Semi cut off type luminaries for uniform illumination.
When width of the road Mounting height, streetlights shall be arranged on single side of the
road.
When width of the road is > Mounting height but is 1.5 times the mounting height, street lights
shall be staggered on opposite sides of the road.
When width of the road is >1.5 times the mounting height but is not exceeding 2 times, street
lights shall be located on either side of the road one opposite to other.
Lighting transformer (delta / star) rating shall not exceed 100KVA.
Emergency lighting shall be 25% of normal lighting.
Lighting panels shall generally be 3 way, 4 way or 6 way types.
Stroboscopic Effect Use twin or multi lamp luminaries in which lamps are connected in
lead-lag circuit with the help of power factor improvement capacitors.
Connect successive rows of lighting fixtures to different phases.
Each circuit shall be loaded up to 1800W to 2000W.
Large rooms shall be provided with more than one phase.
Wiring Industrial buildings Surface exposed wiring with Cu/Al conductor, PVC insulated
wires in rigid steel conduits provided with black enamelling or
hot dip galvanizing.
Non critical areas Surface exposed PVC conduit wiring with Cu/Al conductor,
PVC insulated wires.
Admin. bldgs/areas Concealed conduit wiring with Cu conductor, PVC insulated
wires drawn in rigid steel black enameled conduits. If client
insists, PVC conduits with suitable sealing at joints may be
considered.
Earthing 12 SWG GI wire or 16/18 SWG CU wire or 3 rd core in case of
3 core cables.
Switch derating factors Piano key type - 50%
Toggle and tumbler type - 60%
Industrial and rotary heavy duty type - 80%
Socket derating factors Decorative type - 50%
Industrial type - 80%
Luminous efficacy(lumens/watt)
Tubular Fluorescent - 58 to 70 for warm white
- 49 to 62 for cool daylight
Triband phosphor fluorescent - 85 to 95.
Compact fluorescent lamps - 47 to 82.
Tungsten - 9 to 15
Tungsten halogen - 17 to 25.
HPMV - 43 to 57.
HPSV - 90 to 120.
Metal halide - 60 to 85.
LPSV - 120 to 175.
Operating life
Gas filled incandescent (GLS) - 1000Hrs.
Fluorescent lamps (20W, 40W & 65W) - 5000Hrs.
CFL(7W, 9W, 11W, 13W, 15W, -
18W, 20W, 23W & 25W)
HPMV - 5000Hrs.
Metal halide - 8000 to 10,000Hrs.
HPSV & LPSV - 12,000 to 14,000Hrs.
Recommended illumination levels
Sl.no Area description Recommended
illumination level
1 Unit control room & Switchyard control room 500
2 Control rooms other than those above 300
3 Switchgear / MCC rooms 250
4 TG building-operating floor 250
5 Pump house, Compressor house, DG 250
house, WT plant etc.
6 Battery room 250
7 Cable vaults in TG buildings 150
8 Aux.equipment area in TG buildings 200
9 Boiler platforms (outdoor) 50
10 Boiler platforms (indoor) 150
11 Outdoor conveyors (exposed) 50
12 Indoor conveyers 150
13 Crusher house & junction towers 150
14 Switchyard and transformer yard
14.1 General (coverage factor 3) 10-20
14.2 On equipment (coverage factor 2) 30-35
15 Coal mill area (indoor) 100
16 Marshalling yards, Stockyards, coal storage 25-50
and unloading areas (coverage factor 2)
17 Parking areas (indoor)/Sheds 70
18 Ware houses, Stores 150
19 Workshop (medium work) 300
20 Laboratories and test rooms 500
21 Executive offices, conference halls 400
22 Lift landings (indoor) 150
23 Entrances, Corridor, Stairs (indoor) 150
24 Canteen 150
25 Telephone exchange 200
26 Roads (Main with dense traffic) 15
27 Roads (secondary) 10
28 Toilets 100
TCE.M2-EL-GL-S-2200: Lighting installation notes
1.0 Lighting panels and Light control switches shall be installed at a height of 1200mm from floor.
2.0 Minimum size of conduits shall be 20mm dia. in case of exposed system and 25mm in case of
concealed/embedded systems.
3.0 Separate conduits shall be used for AC/Emergency/DC wiring.
4.0 Wires of different phases shall not be run in same conduit.
5.0 For every phase wire, a separate neutral wire shall be run.
6.0 The internal area of the conduit shall be 2.5 times the total area of the cables.
Sl.no Nominal size of Max. no.of 1100V grade, single core PVC
conduit in mm insulated flexible wires
2.5mm2 4mm2 6mm2 10mm2
1.0 20 5 3 2 -
2.0 25 8 6 5 3
3.0 32 - - 8 5
4.0 40 - - - 6
7.0 650/1100V, PVC insulated flexible single core wires shall be used for indoor lighting.
8.0 650/1100V, PVC insulated, armoured, PVC overall sheathed cables shall be used for lighting in
hazardous areas, corrosive areas and for outdoor areas.
9.0 Size of wire shall be chosen to limit the voltage drop to 5%. Minimum area of conductor shall be
2.5mm2 copper and 4mm2 aluminium. Generally, not more than 8 to 10 points shall be wired
in a circuit. For the purpose of calculating connected loads of various circuits, a multiplying
factor of 1.25 shall be assumed to the rated wattage for MV and fluorescent lamps to take into
account, the losses in the control gear. A loading of 100W and 500W shall be assumed for
single phase and 15A receptacles respectively.
10.0 All ceiling fans shall be installed not less than 2.75M above the floor level.
11.0 Fans shall be installed with their blades at least 100mm above the lighting fixtures.
12.0 Lighting fixtures, receptacles, switches, conduits and junction boxes shall be earthed by
12SWG GI wire run along the entire length of the conduit between the fixture and the
corresponding lighting panel where it shall be connected to the station earth.
13.0 For outdoor earthing of lighting poles and junction boxes on the poles, two (2) nos. 25 x 3mm
GS flat shall be tapped off from 25 x 3mm MS flat buried in ground at a depth of 600mm. The
earth conductor shall be connected to the nearby main earthing grid at the first and last poles
of each feeder circuit and at some intermediate poles.
