General Technical Information

The technical information presented in this catalog is intended to provide basic fundamentals of lighting technology and terminology. In addition, there are a variety of references pertaining specifically to the lamp types that appear in the catalog, such as bulb types, filament configurations, part number suffixes and rated life data.

Lamp Number

All lamps are identified by a standard industry number indicating physical and electrical characteristics, design voltage, current, mean spherical candela (MSCD) or end foot candles (EFC) (whichever is applicable), filament configuration, rated life, and primary applications. The number is sometimes followed by a suffix denoting material and/or color characteristics.

Physical Characteristics
Bulb Type
Bulb shape is indicated by one of the following letters:

B Blister RP Reflector Parabolic
Globular S
PAR Parabolic Aluminized
T Tubular
R Reflector TL
Tubular, Lens end
Attributive Suffixes
The suffixes below denote material and/or color:
A Amber-coated K Krypton-filled
F Frosted NA Natural amber
H Halogen-filled NI Nickel-plated base
IF Inside frosted Q Quartz-filled

Light Center Length (LCL)
LCL is measured from the geometric center of the lighted filament to that part of the base listed below:
Double Contact (D.C.)
Bayonet Top of base pin
Double Contact Index
Top of lower base pin
Midget Bi-Pin Base
Flat bottom of base
Midget Grooved Base
Center of groove
Midget Flanged Base
Top of the flange
Miniature Bayonet
Top of base pin
Screw Bases
Bottom of end contact
Single Contact (S.C.)
Bayonet Top of base pin
Single Contact Midget Flanged
Top of flange
Single Contact Miniature Flanged
Top of bosses in flange
Single Contact or Double
Contact Prefocus
Bottom of indentations on
prefocusing collar
Wedge Base
Center of notch

Filament Configurations
These are identified by the letters below and a suffix number (or number and letter) indicating the shape of the filament and the number of any supports.  
S Straight
C Coiled Wire
CC Coiled Coil
Click here to view filament configurations.


Electrical Characteristics
Design Volts
The socket voltage for which the lamp was originally designed and at which the following characteristics are measured:
Design Amps
The approximate current which the lamp will draw at design volts.
The approximate power the lamps will consume at design volts.
Watts = Amps x Volts
Mean Spherical Candela (MSCD)
The average value of the luminous intensity of a light source in all directions. To convert MSCD to Lumens, multiply by 4pi (12.57).
Approximate Initial Peak Beam Candlepower (AIPBC)
The initial peak beam candlepower of a sealed beam lamp is the amount of light at the point of highest intensity in the beam (historically known as the approximate initial maximum beam candlepower).
End Foot Candles (EFC)
A measure of that portion of the total light output of a T-2 lamp that passes through a .250" orifice placed at the end of the lamp.
Rated Life
The rated average laboratory life to be expected operating the lamps on stationary racks, energized with regulated D.C. voltage. Actual service life will vary with application.
In incandescent lamps, the filament resistance, temperature, current, watts, light output, and life are all greatly affected by the voltage. Empirical equations are available, relating those parameters to voltage over ranges of as much as 10% from nominal voltage. The designer may improve one parameter by changing the voltage, but in doing so shifts all the other parameters. For example, the life varies so that a small decrease in voltage will greatly extend the life; but the light output will simultaneously decrease as the fourth power of that voltage. The nomograph and curve diagrams below show the interrelationships of current, candlepower, and operating life to voltage.
All life data presented in the catalog are given as B50 @ 14.0 volts for halogen products and at bulb rated voltage for all others unless noted.

Click here for more information on lamp life measurements.

Fig.1 Click on graph to enlarge.

Fig.2 Click on graph to enlarge.