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Lighting Reference Guide – Incandescent Lamps

7 Incandescent Lamps

a. Standard Incandescent Lamps

Construction

  • A typical construction of an incandescent lamp is shown in the figure below.
  • An incandescent lamp produces light by using electric current to heat a metallic filament to a high temperature (above 5000° C/ 9000° F).
  • A tungsten filament is used because of its high melting point and low rate of evaporation at high temperatures.
  • The filament is coiled to shorten the overall length and to reduce thermal loss.
  • The filament is enclosed in a glass bulb filled with inert gas at low pressure.
  • The inert gas permits operation at higher temperatures, compared to vacuum, resulting in a smaller evaporation rate of the filament.
  • The bulbs are often frosted on the inside to provide a diffused light instead of the glaring brightness of the unconcealed filament.

Typical Construction of an Incandescent Light

Typical Construction of an Incandescent Light


Shapes and Designation

Shapes and Designation


Shape Code

A Arbitrary (standard) – universal use for home lighting
B Bullet – decorative
BR Bulging reflector – for substitution of incandescent R lamps
C Cone shape – used mostly for small appliances and indicator lamps
ER Elliptical reflector – for substitution of incandescent R lamps
F Flame – decorative interior lighting
G Globe – ornamental lighting and some floodlights
P Pear – standard for streetcar and locomotive headlights
PAR Parabolic aluminized – used in spotlights and floodlights reflector
S Straight – lower wattage lamp
– sign and decorative
T Tubular – showcase and appliance lighting

Lamp Designation

A lamp designation consists of a number to indicate the wattage, a shape code and a number to indicate the approximate major diameter.

  Example: 60A19

    60: Wattage (60W)
     A: Bulb shape
    19: Maximum bulb diameter, in eighths of an inch.

Characteristics

Colour rendering index – 97 (CRI)
– excellent CRI

Colour temperature – 2,500 to 3,000 K
– warm colour

Luminous efficacy – 10 to 35 lumens per watt
– lowest efficacy of all light sources
– efficacy increases with lamp size

Lamp life (hours) – 1,000 to 4,000 (typical 1,000)
– shortest life of all light sources
– longer life lamps have lower efficacy

General – first developed and most common lamps

Lamp configuration – point source

Lamp watts – 1 to 1,500 W

Lamp lumen – 80% to 90% depreciation factor (LLD)

Warm–up time – instant

Restrike time – instant

Lamp cost – low
– lowest initial cost
– highest operating cost

Main applications – residential
– merchandising display lighting

More Information

  • Refer to lamp manufacturers’ catalogues.
Lamp
Designation
Lamp
Watts
Rated
Lamp
Life
(hrs)
Initial
Lumens
Initial
Lumens
per
Watt
Mean
Lumens
Mean
Lumens
per
Watt
Colour
Temp
Deg K
LLD
Standard                
25 A 19 25   1,000 270   10.8     2,550 0.79
40 A 19 40   1,000 510   12.8     2,650 0.87
60 A 19 60   1,000 855   14.3     2,790 0.93
100 A 19 100   1,000 1,650   16.5 1,535   15.4 2,870 0.90
150 A 23 150   1,000 2,780   18.5 2,585   17.2 2,925 0.89
200 PS 30 200   1,000 3,400   17.0     2,925 0.85
300 PS 30 300   1,000 5,720   19.1 5,205   17.4 3,000 0.82
500 PS 35 500   1,000 10,750   21.5 9,783   19.6 3,050 0.89
1000 PS 52 1,000   1,000 23,100   23.1 21,252   21.3 3,030 0.89
1500 PS 52 1,500   1,000 33,620   22.4 28,241   18.8 3,070 0.78
ER Lamps                
30 R 20 30   2,000 200    6.7        
50 R 20 50   2,000 320    6.4        
75 R 20 75   2,000 500    6.7        
BR & ER Lamps              
50 ER 30 50   2,000 320    6.4        
75 ER 30 75   2,000 580    7.7        
120 ER 40 120   2,000 1,475   12.3        
PAR Lamps              
65 PAR 38 65   2,000 765   11.8        
75 PAR 38 75   2,000 1,040   13.9        
120 PAR 38 120   2,000 1,370   11.4        
150 PAR 38 150   2,000 1,740   11.6 1,462    9.7   0.78
200 PAR 46 200   2,000 2,300   11.5        
300 PAR 56 300   2,000 3,840   12.8        
500 PAR 64 500   2,000 6,500   13.0        
Note: CRI for incandescent lamps is typically 97.
  • The lamp charts throughout this publication are intended for comparison purposes
   only; please refer to the most recent lamp manufacturer's catalogues or websites
   for up–to–date information on lamp part numbers and availability.

b. Tungsten Halogen Lamps

Construction

  • The quartz tungsten halogen lamp is another type of incandescent lamp.
  • The conventional incandescent lamp loses filament material by evaporation which is deposited on the bulb wall, leading to bulb blackening and reduced lamp efficacy during the life of the lamp.
  • When a halogen element is added to the filling gas under certain design conditions, a chemical reaction occurs, as a result of which evaporated tungsten is redeposited on the filament, preventing any deposits on the bulb wall.
  • The bulb of the tungsten halogen lamp is normally made of quartz glass to withstand the lamp’s high–temperature operating conditions.
  • The fixture often incorporates a reflector for better heat dissipation and beam control.

Shapes and Designation

Shape Code

Tubular:T3 Line voltage tungsten halogen lamp – double–ended
Tubular:T10 Line voltage tungsten halogen lamp – single–ended
Tubular:T6 Line voltage tungsten halogen lamp – single–ended
Tubular:T–4 Line voltage tungsten halogen lamp – without reflector
Tubular:T–3 Low voltage tungsten halogen lamp – without reflector
Maxi–spot Low voltage tungsten halogen lamp – with reflector
Mini–spot Low voltage tungsten halogen lamp – with reflector
PAR 36 Low voltage tungsten halogen lamp – PAR36 reflector
MR16 Low voltage tungsten halogen lamp – MR16 reflector

Low Voltage Tungsten Halogen

  • Operates at low voltage – mainly 12 V,
  • Each fixture includes a transformer – supplying the low voltage to the lamp and are compact in size,
  • These are more efficient than standard incandescent,
  • These have longer life than standard incandescent,
  • These are used mainly for display lighting.
Lamp
Designation
Lamp
Watts
Rated
Lamp
Life
(hrs)
Initial
Lumens
Initial
Lumens
per
Watt
Mean
Lumens
Mean
Lumens
per
Watt
Colour
Temp
Deg
K
LLD
Single-Ended Quartz                  
Q 75CL 75   2,000   1,400 18.7        
Q 100 CL 100     750   1,800 18.0     3,000  
Q 150 CL/DC 150   1,000   2,800 18.7  2,688 17.9 2,850 0.96
Q 250 CL/DC 250   2,000   5,000 20.0  4,850 19.4 2,950 0.97
Q 400 CL/MC 400   2,000   8,250 20.6     2,950  
Q 500 CL/DC 500   2,000 10,450 20.9     2,950  
Double–Ended Quartz                  
Q 200 T3/ CL 200   1,500   3,460 17.3     2,850 0.96
Q 300 T3/CL 300   2,000   5,950 19.8     2,950 0.96
Q 400 T4/CL 400   2,000   7,750 19.4     2,950 0.96
Q 500 T3/CL 550   2,000 11,100 22.2 10,767 21.5 3,000 0.96
Q1000 T6/CL 1,000   2,000 23,400 23.4     3,050 0.96
Q1500 T3/CL 1,500   2,000 35,800 23.9 34,726 23.2 3,050 0.96
Low Voltage MR Types
20MR16FL 20W 4,000   700 CBCP          
50MR16FL 50W 4,000 2,000 CBCP          
65MR16FL 65W 4,000 2,100 CBCP          
Notes: CRI for incandescent lamps is typically 97.
  CRI for tungsten halogen (quartz) lamps is slightly better than
   other incandescent lamps
  • CBCP = Centre Beam Candle Power, used instead of lumens with
   the low voltage reflector lamps
See Also: • Lamp manufacturer's catalogues.


c. Halogen PAR Lamps

General Description

  • Halogen PAR lamps are lamps with a Parabolic Aluminum Reflector (PAR) which use a halogen capsule instead of a simple filament.
  • The halogen capsule includes a tungsten filament and halogen gas.

PAR Lamp Families

  • PAR lamps have evolved into four families, listed below, from lowest to highest efficiency:
  • standard PAR lamps
  • energy saving PAR lamps
  • halogen PAR lamps
  • Infra Red (IR) halogen PAR lamps.
  • All PAR lamps have an aluminum or silver coating reflector on part of the bulb’s surface.
  • PAR lamps are used for directional lighting, i.e., highlighting or spot lighting.
  • Most common size is the PAR 38
  • Other sizes include PAR 30, PAR 20 and PAR 16.
  • Beam spreads are described as narrow spot (NS), spot (SP) and flood (FL).

Standard PAR Lamps (see also Section 7a, Incandescent Lamps)

  • Use a tungsten filament but no halogen gas, i.e., no halogen capsule.
  • Lamp watts: 75 W, 100 W, 150 W
  • Life: 2,000 hours.

Halogen PAR Lamps

  • Halogen PAR lamps use a halogen capsule instead of a tungsten filament.
  • Lamp watts: 45 W, 65 W, 90 W.
  • Life: 2,000 hours.

PAR 38 Lamp Replacement

  Standard
PAR
Energy
Saving
PAR
Halogen
PAR
IR
Halogen
PAR
  75 55,65 45  
  100 80,85
  150 120 90 60
  100
Life Hours 2,000 2,000 2,000 2,000
Energy 20% less 40% less 60% less
Light same same same
Colour same whiter whiter
GE Brand PAR Watt–Miser Halogen Halogen
    PAR Performance Plus PAR IRPAR
Philips Brand PAR Econ–O–PAR Masterline
Sylvania Brand PAR Super Saver Capsylite
Note: • Replacements provide about the same light beam candlepower around the
   centre of the beam.
  • The standard PAR is used as a basis for the comparisons shown in the table.

Applications

Highlighting merchandise in stores and window displays:

  • Downlights,
  • Accent lighting,
  • Outdoor lighting.

Advantages

Halogen PAR lamps have many advantages over standard and energy saving PAR lamps:

  • energy savings in the order of 40% – 60%;
  • whiter light;
  • constant light output throughout lamp life without lamp darkening.

Limitations

Halogen PAR lamps are more expensive than standard and energy saving PAR.

Assessment

  • Halogen PAR lamps provide energy savings which outweigh the lamp price difference in less than a year.
  • Halogen PAR lamps provide better quality light.
Lamp
Designation
Lamp
Watts
Rated
Lamp
Life
(hrs)
Initial
Lumens
Initial
Lumens
per
Watt
Mean
Lumens
Mean
Lumens
per
Watt
Colour
Temp
Deg
K
LLD
PAR Quartz            
Q90 PAR38 90   2,000 1,740   19.3       0.96
Q150 PAR38 140   4,000 2,000   13.3 1,900 12.7 2,900  
Q250 PAR38 250   6,000 3,220   12.9     2,900  
Q500 PAR56 500   4,000 7,000   14.0     2,950  
Q1000 PAR64 1,000   4,000 19,400   19.4     3,000  


d. Halogen PAR and MR IR (Infrared)Lamps

  • Halogen PAR IR lamps use a halogen capsule with an infrared (IR) coating film on the capsule surface.
  • The IR film is visually transparent and reflects heat back to the filament, making the lamp more efficient.
  • These lamps are the most efficient incandescent PAR lamps.
  • Lamp watts: 40 W, 50 W, 55 W, 60 W, 80 W, 100 W, and others.
  • Life: 3,000 to 6,000 hours.
  • These are an excellent replacement for conventional incandescent PAR lamps.

Standard incandescent PAR Lamp:
150PAR38fl, 2,000 hrs, 1,700 initial lumens, 11.3 lm/W

Halogen PAR Lamp:
120PAR38FL, 2,000 hrs, 1,900 initial lumens, 15.8 lm/W

Halogen HIR PAR Lamp:
90PAR38HIR/FL, 4,000 hrs, 2,030 initial lumens, 22.5 lm/W

e. Infrared Heat Lamps

Infrared Heat Lamps
  • The Energy Radiator reflects the heat forward

  • The heat loss in the conventional (Soft Glass) IR lamp

  • Skirted PAR lamp base for increased support
 

General Description

Infrared heat lamps, also known as IR lamps, or simply heat lamps, are specially–designed incandescent lamps which produce mostly heat and little light.

Types

  • There are two basic types:
  • PAR type      – i.e., pparabolic aluminum reflector lamps.
  • R type           – i.e., reflector type lamps.

  • PAR type lamps are newer and more efficient. They include the following sizes:
  • 175 W PAR 38,
  • 100 W PAR 38.

  • R type lamps are older and have been used more extensively. They include the following sizes:
  • 250 W R40,
  • 175 W R40,
  • 150 W R40.

  • The 250 W R40 lamp is presently the most widely–used heat lamp in the market.

  • Most infrared heat lamps have a red front glass, but lamps with clear white glass are also available.

PAR Lamps Can Replace R Lamps

  • PAR lamps are newer and more efficient than R lamps.
  • PAR lamps can replace higher wattage R lamps with an equivalent heat output.
  • Typical replacements:
  • 175 W PAR can replace 250 W R lamp
  • 100 W PAR can replace 175 W and 150 W R lamps
  • The parameters used to compare the two types of lamps are listed below.

Technical Data

Lamp Type Input
Wattage (W)
Heat
Output (W)
Heat Lamp
Efficiency (%)
0 to 30
Heat Output (W)
175 W PAR 175 115     65.7 74
100 W PAR 100 65     65.0 42
250 W R 250 144     57.6 77.5
175 W R 175 95     54.3 46
150 W R - - - -
  • Input wattage is the nominal lamp wattage.
  • Heat output is the useful heat available from the front of the lamp i.e., the heat produced in a solid angle of 90° around the lamp axis in the front hemisphere.
  • The heat output numbers included in the table above have been measured in a laboratory test.
  • Heat lamp efficiency is defined as the ratio of the heat output over the nominal input wattage.
  • Heat output in the 0° to 30° zone is the heat output near the centre axis of the lamp.

Lifetimes

Nominal lifetimes are listed below (manufacturers' data).

Lamp Type Expected Lifetime(hrs)
175 W PAR 5,000
100 W PAR 5,000
250 W R 5,000
175 W R 5,000
150 W R 5,000
  • Lamp life is defined statistically as the time in hours at which 50% of the lamps are still functioning (while 50% have failed).
  • The expected lifetime of a single lamp is 5,000 hours, but by definition, the actual lifetime can be higher or lower.
  • PAR lamps have a more rugged construction and use a tempered glass not easily broken by thermal shock or mechanical impact.
  • In farm applications, typical conditions include high humidity,
    i.e., RH at least 75% and ammonia levels from 25 to 35 ppm, with an expected negative effect on lamp life.
  • Fluctuations in voltage are common in farms and have a negative effect since higher voltages reduce the expected lifetime.
  • Monitoring line voltage of a large number of lamps in a real farm setting and recording failure rates would provide a comparison of reliability and lamp life between PAR and R type lamps.

175 W PAR Lamps Can Replace 250 W R Lamps

  • The technical data listed on the previous page indicates that the 175 W PAR lamp can be a more efficient replacement for the 250 W R lamp.
  • Replacement results in savings of 75 W per lamp, i.e., 30% energy savings.
  • Heat output is reduced by 29 W.
  • Heat output in the 0° to 30° zone, i.e., heat output near the lamp axis zone, is almost the same for the old and the new lamp (only 3.5 W less).
  • The heat lamp efficiency is improved.

100 W PAR Lamps Can Replace 175 W R Lamps

  • The 100 W PAR lamp can be a more efficient replacement for the
    175 W R lamp.
  • Replacement results in savings of 75 W per lamp, i.e., 43% energy savings.
  • Heat output is reduced by 30 W.
  • Heat output in the 0° to 30° zone, i.e., heat output near the lamp axis zone, is almost the same for the old and the new lamp (only 4 W less).
  • The heat lamp efficiency is improved.

Applications

  • Farm animal heating;
  • In farm animal heating where lamps are on continuously;
  • Restaurants also use them for keeping food warm.

Assessment

  • PAR heat lamps offer a more efficient and overall better alternative to R type of heat lamps.

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