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 |