Electrical Thumb Rules-Illumination-(Part-20)
Watts & Light Brightness | |||
Incandescent Watts | CFL Watts | LED Watts | Lumens (Brightness) |
40 | 8 to 12 | 6 to 9 | 400 to 500 |
60 | 13 to 18 | 8 to 12.5 | 650 to 900 |
75 to 100 | 18 to 22 | 13 to 15 | 1100 to 1750 |
100 | 23 to 30 | 16 to 20 | 1800 to 2779 |
150 | 30 to 55 | 25 to 28 | 2780 |
Minimum Lumens | |
Incandescent (Watt) | CFL , Halozan , LED (Minimum Lumen) |
25 Watt | 200 |
40 Watt | 450 |
60 Watt | 800 |
75 Watt | 1100 |
100 Watt | 1600 |
150 Watt | 2700 |
Wattage Comparison Chart | |||||
Incandescent / Halogens | Mercury Vapor | Metal Halide | High Pressure Sodium | Compact Fluorescent (CFLs) | Light Emitting Diodes (LEDs) |
40 to 60 | 15 to 25 | 5 to 15 | 5 to 15 | 12 to 15 | 5 to 8 |
60 to 75 | 25 to 35 | 15 to 25 | 15 to 25 | 15 to 18 | 7 to 10 |
75 to 100 | 35 to 45 | 20 to 35 | 20 to 35 | 18 to 23 | 10 to 15 |
100 to 150 | 50 to 60 | 25 to 40 | 25 to 40 | 23 to 35 | 15 to 20 |
150 to 200 | 70 to 85 | 35 to 45 | 35 to 45 | 30 to 45 | 20 to 25 |
200 to 250 | 90 to 110 | 40 to 55 | 40 to 55 | 45 to 60 | 25 to 30 |
Luminous efficacy | |
Light type | Typical luminous efficacy (lumens/watt) |
Tungsten incandescent light bulb | 12.5 to17.5 lm/W |
Halogen lamp | 16 to 24 lm/W |
Fluorescent lamp | 45 to 75 lm/W |
LED lamp | 30 to 90 lm/W |
Metal halide lamp | 75 to 100 lm/W |
High pressure sodium vapor lamp | 85 to 150 lm/W |
Low pressure sodium vapor lamp | 100 to 200 lm/W |
Mercury vapor lamp | 35 to 65 lm/W |
Selection parameter of LED Bulbs | |||
Parameter | Average | Good | Best |
Lumens/Watt | 75 | 90 | 100 |
Power Factor | 0.7 | 0.8 | 0.9 |
CRI | 60 | 70 | 80 |
LED Life in Hours | 15000 | 25000 | 50000 |
Available CRI of Various Lighting Sources | |
Source | CRI |
Incandescent / Halogens | >95 |
T8 Linear Fluorescent | 75 to 85 |
Cool White Linear Fluorescent | 62 |
Compact Fluorescent | 82 |
Metal Halide | 65 |
High Pressure Sodium (HPS) | 22 |
LED | 80 to 98 |
Color Accuracy – CRI Chart | |
CRI | Rating |
>90 | Great |
80 to 90 | Very Good |
70 to 80 | Good |
60 to 70 | Good |
40 to 60 | Poor |
Color Temperature & CRI Chart | |||
Kelvin | Light Effect | CCT | CRI |
< 3600K | Incandescent Fluorescent (IF) | 2750 | 89 |
< 3600K | Deluxe warm white (WWX) | 2900 | 82 |
< 3600K | Warm white (WW) | 3000 | 52 |
3200K to 4000K | White | 3450 | 57 |
3200K to 4000K | Natural white (N) | 3600 | 86 |
Above 4000 K | Light white (LW) | 4150 | 48 |
Above 4000 K | Cool white (CW) | 4200 | 62 |
Above 4000 K | Daylight (D) | 6300 | 76 |
Above 4000 K | Deluxe Daylight (DX) | 6500 | 88 |
Above 4000 K | Sky white | 8000 | 88 |
Color Temperature & CRI | ||
Lighting source | Color Temperature | Color Rendering Index |
High Pressure Sodium Lamp | 2100K | 25 |
Incandescent Lamp | 2700K | 100 |
Tungsten Halogen Lamp | 3200K | 95 |
Tungsten Halogen Lamp | 3200K | 62 |
Clear Metal Halide Lamp | 5500K | 60 |
Natural Sun Light | 5000K to 6000K | 100 |
Day Light Bulb | 6400K | 80 |
Lighting Source CCT | |
Source | Color temperature in Kelvin |
Skylight (blue sky) | 12,000 – 20,000 |
Average summer shade | 8000 |
Light summer shade | 7100 |
Typical summer light (sun + sky) | 6500 |
Daylight fluorescent | 6300 |
Xenon short-arc | 6400 |
Overcast sky | 6000 |
Clear mercury lamp | 5900 |
Sunlight (noon, summer, mid-latitudes) | 5400 |
Design white fluorescent | 5200 |
Special fluorescents used for color evaluation | 5000 |
Daylight photoflood | 4800 – 5000 |
Sunlight (early morning and late afternoon) | 4300 |
Bright White Deluxe Mercury lamp | 4000 |
Sunlight (1 hour after dawn) | 3500 |
Cool white fluorescent | 3400 |
Photoflood | 3400 |
Professional tungsten photographic lights | 3200 |
100-watt tungsten halogen | 3000 |
Deluxe Warm White fluorescent | 2950 |
100-watt incandescent | 2870 |
40-watt incandescent | 2500 |
High-pressure sodium light | 2100 |
Sunlight (sunrise or sunset) | 2000 |
Candle flame | 1850 – 1900 |
Match flame | 1700 |
Skylight (blue sky) | 12,000 – 20,000 |
Average summer shade | 8000 |
Light summer shade | 7100 |
Typical summer light (sun + sky) | 6500 |
Daylight fluorescent | 6300 |
Xenon short-arc | 6400 |
Overcast sky | 6000 |
Clear mercury lamp | 5900 |
Sunlight (noon, summer, mid-latitudes) | 5400 |
Design white fluorescent | 5200 |
Special fluorescents used for color evaluation | 5000 |
Daylight photoflood | 4800 – 5000 |
Sunlight (early morning and late afternoon) | 4300 |
Bright White Deluxe Mercury lamp | 4000 |
Sunlight (1 hour after dawn) | 3500 |
Cool white fluorescent | 3400 |
Photoflood | 3400 |
Professional tungsten photographic lights | 3200 |
100-watt tungsten halogen | 3000 |
Deluxe Warm White fluorescent | 2950 |
100-watt incandescent | 2870 |
40-watt incandescent | 2500 |
High-pressure sodium light | 2100 |
Sunlight (sunrise or sunset) | 2000 |
Candle flame | 1850 – 1900 |
Match flame | 1700 |
CCT – Correlated Color Temperature | |||
Kelvin | Associated Effects | Type of Bulbs | Appropriate Applications |
2700° | Warm White, Very Warm White | Incandescent bulbs | Homes, Libraries, Restaurants |
3000° | Warm White | mostly halogen lamps, Slightly whiter than ordinary incandescent lamps | Homes, Hotel rooms and Lobbies, Restaurants, retail Stores |
3500° | White | Fluorescent or CFL | Executive offices, public reception areas, supermarkets |
4100° | Cool White | Office, classrooms, mass merchandisers, showrooms | |
5000° | Daylight | Fluorescent or CFL | Graphic industry, hospitals |
6500° | Cool Daylight | Extremely white‘ | Jewelry stores, beauty salons, galleries, museums, printing |
Average Life Cycle | |
Source | Average Life |
Incandescent / Halogens | 1,000 to 4,000 hours |
CFL | 6,000 hours |
LED | 15,000 to 50,000 hrs |
Lamp Properties | ||||
Option | Life (hrs) | Efficacy (lpw) | CRI | Color of light |
LED | 35,000-50,000 | 30-300 | ≥70 | White |
High Pressure Sodium | 20,000-24,000 | 50-110 | ≤40 | Orange |
Metal Halide | 6,000-15,000 | 72-76 | 75-90 | White |
Mercury Vapor | 16,000-24,000 | 30-50 | 40-60 | Blue-White |
Fluorescent | 10,000-24,000 | 40-140 | 20-80 | White |
Illuminance Levels for Signage Lighting | ||
Light Intensity | Foot candles | Lux |
Low | 10 to 20 | 100 to 200 |
Medium | 20 to 40 | 200 to 400 |
High | 40 to 80 | 400 to 800 |
Types of Lamp Technologies | ||||
Type of Lamp | Luminous Efficacy (lm/W) | Color Rendering Properties | Lamp life in Hrs. | Lamp life in Hrs. |
High Pressure Mercury Vapor (MV)
| 35-36 lm/W | Fair | 10000-15000
| High energy use, poor lamp life |
Metal Halide (MH) | 70-130 lm/W | Excellent | 8000-12000 | High luminous efficacy, poor lamp life |
High Pressure Sodium Vapor (HPSV)
| 50-150 lm/W | Fair | 15000-24000 | Energy-Efficient, poor color rendering
|
Low Pressure Sodium Vapor (LPSV)
| 100-190 lm/W
| Very Poor | 18000-24000 | Energy-Efficient, very poor color rendering
|
Low Pressure Mercury Fluorescent Tubular Lamp (T12 & T8)
| 30-90 lm/W | Good | 5000-10000 | Poor lamp life, medium energy use, only available in low wattages
|
EE Fluorescent Tubular Lamp (T5)
| 100-120 lm/W
| Very Good | 15000-20000 | long lamp life, only available in low wattages
|
Light Emitting Diode (LED)
| 70-160 lm/W | Good | 40000-90000 | High energy savings, low O&M, long life, no mercury, high
|
Comparison of Lamp Technology | |||||
Technology | Mercury Vapor | High Pressure Sodium Vapor | Induction | New Ceramic | Induction New Ceramic LED |
Description | Older Very Common white light HID light source | Most common HID light source used in street lighting | White light electrode less light source with long operating life | White light HID technology | White-light, solid-state light source |
Pros | Low initial cost | Low initial cost | maintenance-free | White light | Small size |
Longer lamp life | Longer lamp life | High efficacy | Longer lamp life | Very long time life | |
White light | High lamp efficacy (70-150) lumens/watt) | Excellent color rendering index | High lamp efficacy (115) lumens/watt) | Switching has no effect on life | |
Sudden failure are uncommon | Instant start and restrike operations | High fixture efficiency | Contains no mercury | ||
No flickering, strobing or noise | low ambient temperature operations | ||||
Low temperature operations | High lumens efficacy | ||||
No flickering, strobing or noise | |||||
Instant start and restrike operations | |||||
Cons | Poor lamp efficacy (34-58) lumens/watt) | Low CRI | High initial cost | High price | High price |
Low fixture efficiency | Contains mercury | Low lamp efficacy (36-64 ) lumens/watt) | Lower luminaire efficacy | Low luminous flux | |
Contains mercury | Contains mercury | Higher electricity consumption | CRI can be low | ||
Contains mercury | Risk of glare |
Restrick Rate of Bulbs | ||
HID lamp type | Time to reach 80% light output | Time to Restrike |
Mercury | 5-7 min | 3-6 min |
Metal halide | 2-4 min | 10-15 min |
High-pressure sodium | 3-4 min | 1 min |
Mounting Height of Light according to Types of Bulbs | ||
HID lamp type | Watt | Mounting Height |
Mercury | 100 Watt | 8 Meter |
175 Watt | 10 Meter | |
250 Watt | 15 Meter | |
400 Watt | 23 Meter | |
1000 Watt | 30 Meter | |
Metal halide | 70 Watt | 7 Meter |
100 Watt | 10 Meter | |
175 Watt | 16 Meter | |
250 Watt | 20 Meter | |
400 Watt | 25 Meter | |
1000 Watt | 35 Meter | |
High-pressure sodium | 35 Watt | 6 Meter |
50 Watt | 7 Meter | |
70 Watt | 8 Meter | |
100 Watt | 12 Meter | |
175 Watt | 18 Meter | |
250 Watt | 25 Meter | |
400 Watt | 30 Meter | |
1000 Watt | 38 Meter |
Various Lamp Comparison | |||||
As per CPWD | |||||
Lamp type | Range | Luminous LUX | Efficacy (lm/W) | Average Life (hr) | Color Rendering (Ra) |
CFL | 18W-36W | 1200-2900 | 60-80 | 15000 | 75-85 |
Fluorescent-T5 | 28W-54W | 2900-4850 | 90-104 | 24000 | 80-90 |
Fluorescent-T8 | 18W-36W | 750-3250 | 50-90 | 20000 | 80-85 |
Fluorescent-T12 | 20W-40W | 950-2450 | 48-61 | 12000 | 50-75 |
Halogen | 50W | 1200 | 24 | 2000 | 75-90 |
Metal halide | 70W-250W | 5300-25000 | 76-100 | 12000 | 70-90 |
High pressure sodium vapor | 70W-1000W | 5600-130000 | 80-130 | 20000 | 20-65 |
Low pressure sodium vapor | 55W-135W | 8100-32000 | 100-230 | 20000 | 20-65 |
Induction lamp | 70W-150W | 6500-12000 | 80-95 | 100000 | 65-90 |
LED | 3W-120W | 750-14000 | 80-100 | 80000 | 65-90 |
Lamp Comparison As per CPWD | ||||||
Lamp type | LED (Warm White) | LED (Cool White) | T5 Lamp | CFL Lamp | HPSV Lamp | Metal Lamp Halide |
CRI | 80-85 | 75 | 85 | 85 | 22 | 60-90 |
Efficiency in lm/w | 80 | 132 | 90 | 70 | 95-110 | 65-70 |
Usable lm/w | 55-65 | >100 | 75-85 | 50-60 | 55-65 | 35-40 |
Life (Hrs.) | 50k+ | 50k+ | 30k | 8-10k | 24k | 10k-20K |