Electrical Thumb Rules-Illumination-(Part-20)

Watts & Light Brightness

Incandescent Watts CFL WattsLED WattsLumens (Brightness)
408 to 126 to 9400 to 500
6013 to 188 to 12.5650 to 900
75 to 10018 to 2213 to 151100 to 1750
10023 to 3016 to 201800 to 2779
15030 to 5525 to 282780

 

Minimum Lumens

Incandescent (Watt)CFL , Halozan , LED (Minimum Lumen)
25 Watt200
40 Watt450
60 Watt800
75 Watt1100
100 Watt1600
150 Watt2700

 

Wattage Comparison Chart

Incandescent
/
Halogens
Mercury VaporMetal    HalideHigh
Pressure
Sodium
Compact
Fluorescent
(CFLs)
Light
Emitting Diodes
(LEDs)
40 to 6015 to 255 to 155 to 1512 to 155 to 8
60 to 7525 to 3515 to 2515 to 2515 to 187 to 10
75 to 10035 to 4520 to 3520 to 3518 to 2310 to 15
100 to 15050 to 6025 to 4025 to 4023 to 3515 to 20
150 to 20070 to 8535 to 4535 to 4530 to 4520 to 25
200 to 25090 to 11040 to 5540 to 5545 to 6025 to 30

 

Luminous efficacy

Light typeTypical luminous efficacy (lumens/watt)
Tungsten incandescent light bulb12.5 to17.5 lm/W
Halogen lamp16 to 24 lm/W
Fluorescent lamp45 to 75 lm/W
LED lamp30 to 90 lm/W
Metal halide lamp75 to 100 lm/W
High pressure sodium vapor lamp85 to 150 lm/W
Low pressure sodium vapor lamp100 to 200 lm/W
Mercury vapor lamp35 to 65 lm/W

 

Selection parameter of LED Bulbs

ParameterAverageGoodBest
Lumens/Watt7590100
Power Factor0.70.80.9
CRI607080
LED Life in Hours150002500050000

 

Available CRI of Various Lighting Sources

SourceCRI
Incandescent / Halogens>95
T8 Linear Fluorescent75 to 85
Cool White Linear Fluorescent62
Compact  Fluorescent82
Metal   Halide65
High Pressure Sodium (HPS)22
LED80 to 98

 

Color Accuracy – CRI Chart

CRIRating
>90Great
80 to 90Very Good
70 to 80Good
60 to 70Good
40 to 60Poor

 

Color Temperature & CRI Chart

KelvinLight EffectCCTCRI
< 3600KIncandescent Fluorescent (IF)275089
< 3600KDeluxe warm white (WWX)290082
< 3600KWarm white (WW)300052
3200K to 4000KWhite (W)345057
3200K to 4000KNatural white (N)360086
Above 4000 KLight white (LW)415048
Above 4000 KCool white (CW)420062
Above 4000 KDaylight (D)630076
Above 4000 KDeluxe Daylight (DX)650088
Above 4000 KSky white800088

 

Color Temperature & CRI

Lighting sourceColor TemperatureColor Rendering Index
High Pressure Sodium Lamp2100K25
Incandescent Lamp2700K100
Tungsten Halogen Lamp3200K95
Tungsten Halogen Lamp3200K62
Clear Metal Halide Lamp5500K60
Natural Sun Light5000K to 6000K100
Day Light Bulb6400K80

 

Lighting Source CCT

SourceColor temperature in Kelvin
Skylight (blue sky)12,000 – 20,000
Average summer shade8000
Light summer shade7100
Typical summer light (sun + sky)6500
Daylight fluorescent6300
Xenon short-arc6400
Overcast sky6000
Clear mercury lamp5900
Sunlight (noon, summer, mid-latitudes)5400
Design white fluorescent5200
Special fluorescents used for color evaluation5000
Daylight photoflood4800 – 5000
Sunlight (early morning and late afternoon)4300
Bright White Deluxe Mercury lamp4000
Sunlight (1 hour after dawn)3500
Cool white fluorescent3400
Photoflood3400
Professional tungsten photographic lights3200
100-watt tungsten halogen3000
Deluxe Warm White fluorescent2950
100-watt incandescent2870
40-watt incandescent2500
High-pressure sodium light2100
Sunlight (sunrise or sunset)2000
Candle flame1850 – 1900
Match flame1700
Skylight (blue sky)12,000 – 20,000
Average summer shade8000
Light summer shade7100
Typical summer light (sun + sky)6500
Daylight fluorescent6300
Xenon short-arc6400
Overcast sky6000
Clear mercury lamp5900
Sunlight (noon, summer, mid-latitudes)5400
Design white fluorescent5200
Special fluorescents used for color evaluation5000
Daylight photoflood4800 – 5000
Sunlight (early morning and late afternoon)4300
Bright White Deluxe Mercury lamp4000
Sunlight (1 hour after dawn)3500
Cool white fluorescent3400
Photoflood3400
Professional tungsten photographic lights3200
100-watt tungsten halogen3000
Deluxe Warm White fluorescent2950
100-watt incandescent2870
40-watt incandescent2500
High-pressure sodium light2100
Sunlight (sunrise or sunset)2000
Candle flame1850 – 1900
Match flame1700

 

CCT – Correlated Color Temperature

KelvinAssociated EffectsType of BulbsAppropriate Applications
2700°Warm White, Very Warm WhiteIncandescent bulbsHomes, Libraries, Restaurants
3000°Warm Whitemostly halogen lamps, Slightly  whiter  than ordinary incandescent lampsHomes, Hotel rooms and Lobbies, Restaurants, retail Stores
3500°WhiteFluorescent or CFLExecutive offices, public reception areas, supermarkets
4100°Cool WhiteOffice, classrooms, mass merchandisers, showrooms
5000°DaylightFluorescent or CFLGraphic industry, hospitals
6500°Cool DaylightExtremely  white‘Jewelry stores, beauty salons, galleries, museums, printing

 

Average Life Cycle

SourceAverage Life
Incandescent / Halogens1,000 to 4,000 hours
CFL6,000 hours
LED15,000 to 50,000 hrs

 

Lamp Properties

OptionLife (hrs)Efficacy (lpw)CRIColor of light
LED35,000-50,00030-300≥70White
High Pressure Sodium20,000-24,00050-110≤40Orange
Metal Halide6,000-15,00072-7675-90White
Mercury Vapor16,000-24,00030-5040-60Blue-White
Fluorescent10,000-24,00040-14020-80White

 

Illuminance Levels for Signage Lighting

Light IntensityFoot candlesLux
Low10 to 20100 to 200
Medium20 to 40200 to 400
High40 to 80400 to 800

 

Types of Lamp Technologies

Type of LampLuminous

Efficacy

(lm/W)

Color

Rendering

Properties

Lamp life in

Hrs.

Lamp life in

Hrs.

High Pressure

Mercury Vapor (MV)

 

35-36 lm/WFair10000-15000

 

High energy use, poor lamp life
Metal Halide (MH)70-130 lm/WExcellent8000-12000High luminous efficacy, poor lamp life
High Pressure

Sodium Vapor

(HPSV)

 

50-150 lm/WFair15000-24000Energy-Efficient, poor color rendering

 

Low Pressure

Sodium Vapor

(LPSV)

 

100-190

lm/W

 

Very Poor18000-24000Energy-Efficient, very poor color rendering

 

Low Pressure

Mercury

Fluorescent Tubular

Lamp (T12 & T8)

 

30-90 lm/WGood5000-10000Poor lamp life, medium energy use, only available in low wattages

 

EE Fluorescent

Tubular Lamp (T5)

 

100-120

lm/W

 

Very Good15000-20000long lamp life, only available in low wattages

 

Light Emitting

Diode (LED)

 

70-160 lm/WGood40000-90000High energy savings, low O&M, long life, no

mercury, high

 

 

Comparison of Lamp Technology

TechnologyMercury VaporHigh Pressure Sodium VaporInductionNew CeramicInduction New Ceramic LED
DescriptionOlder Very Common white light  HID light sourceMost common HID light source used in street lightingWhite light electrode less light source with long operating lifeWhite light HID technologyWhite-light, solid-state light source
ProsLow initial costLow initial costmaintenance-freeWhite lightSmall size
Longer lamp lifeLonger lamp lifeHigh efficacyLonger lamp lifeVery long time life
White lightHigh lamp efficacy (70-150) lumens/watt)Excellent color rendering indexHigh lamp efficacy (115) lumens/watt)Switching has no effect on life
Sudden failure are uncommonInstant start and restrike operationsHigh fixture efficiencyContains no mercury
No flickering, strobing or  noiselow ambient  temperature operations
Low temperature operationsHigh lumens efficacy
No flickering, strobing or  noise
Instant start and restrike operations
ConsPoor lamp efficacy (34-58) lumens/watt)Low CRIHigh initial costHigh priceHigh price
Low fixture efficiencyContains mercuryLow lamp efficacy (36-64 ) lumens/watt)Lower luminaire efficacyLow luminous flux
Contains mercuryContains mercuryHigher electricity consumptionCRI can be low
Contains mercuryRisk of glare

 

Restrick Rate of Bulbs

HID lamp typeTime to reach 80% light outputTime to Restrike
Mercury5-7 min3-6 min
Metal halide2-4 min10-15 min
High-pressure sodium3-4 min1 min

 

Mounting Height of Light according to Types of Bulbs

HID lamp typeWattMounting Height
Mercury100 Watt8 Meter
175 Watt10 Meter
250 Watt15 Meter
400 Watt23 Meter
1000 Watt30 Meter
Metal halide70 Watt7 Meter
100 Watt10 Meter
175 Watt16 Meter
250 Watt20 Meter
400 Watt25 Meter
1000 Watt35 Meter
High-pressure sodium35 Watt6 Meter
50 Watt7 Meter
70 Watt8 Meter
100 Watt12 Meter
175 Watt18 Meter
250 Watt25 Meter
400 Watt30 Meter
1000 Watt38 Meter

 

Various Lamp Comparison

As per CPWD

Lamp typeRangeLuminous LUXEfficacy (lm/W)Average  Life (hr)Color Rendering (Ra)
CFL   18W-36W1200-290060-801500075-85
Fluorescent-T528W-54W2900-4850 90-10424000 80-90
Fluorescent-T8  18W-36W750-325050-902000080-85
Fluorescent-T12 20W-40W950-2450 48-611200050-75
Halogen 50W120024200075-90
Metal halide70W-250W5300-2500076-1001200070-90
High pressure sodium vapor70W-1000W5600-13000080-1302000020-65
Low pressure sodium vapor55W-135W8100-32000100-2302000020-65
Induction lamp70W-150W6500-1200080-9510000065-90
LED    3W-120W750-1400080-1008000065-90

 

Lamp Comparison As per CPWD

Lamp typeLED (Warm White)LED (Cool  White)T5 LampCFL LampHPSV  LampMetal Lamp Halide
CRI80-857585852260-90
Efficiency in lm/w80132907095-11065-70
Usable lm/w55-65>10075-8550-6055-6535-40
Life (Hrs.)50k+50k+30k8-10k24k10k-20K