Shapes and Dimensions



Note: Bulb size or diameter (maximum) is expressed in an eighth of an inch (1/8") for one unit. For instance, a BT56 bulb is 56 eighths of an inch in diameter, or 7 inches in diameter. See ANSI C79.1 for complete details on bulb shapes.

Lamp Maximum Overall Length (M.O.L.):*
MOL is measured from the end of the lamp base to the top of the outer jacket.

Light Center Length (L.C.L.):†
The distance from the light center to a specified reference point on the lamp. 

The diameter is the maximum diameter of the glass bulb.





Arc Tube Maximum Overall Length (M.O.L.):*
The distance between the ends of the bases.

Contact to Contact:
The length between contacts is the distance
between the metal contacts which
are recessed inside the ends of the bases.

Nominal Diameter:
The approximate diameter of the tube.

 * Not a controlled dimension - can vary ±10mm
† A controlled dimension - can vary ±3mm

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