Compact Fluorescent Lamp Base Identification

Compact Fluorescent lamps (bulbs) are either pin-based (they plug into a socket) or they are medium screw-based (they screw into the same socket as common incandescent bulbs). The following describes pin-based compact fluorescent bulbs:

Lamp manufacturers of the National Electrical Manufacturers Association use a generic designation system for compact fluorescent bulbs. This system helps users identify the bulb type and easily cross-reference between manufacturers.

The nema generic designation system for pin-based compact fluorescent lamps consists of four parts:

CF + Shape + Wattage / Abbreviated Base Designation

  • The prefix "CF" is used for all types of compact fluorescent lamps that comply with the American National Standards Institute definition of a self-supporting lamp with a single base.
  • The "Shape" designator is chosen from the following:
    • " T " - twin parallel tubes
    • " Q " - four tubes in a quad formation
    • " TR " - triple tube (including three twin tubes in a delta formation or three tubes in an arch) see footnote below
    • " S " - square shaped
    • " M " - a combination of tubes (multiple) not covered by any of the above shape designators
  • The "Wattage" is the nominal wattage, followed by "W".
  • The "Abbreviated Base Designation" after the "/"separator, is the IEC/ANSI designation which includes the number of pins, but excludes any keyway information. The base designation, which can be determined from lamp catalogs, is essential to differentiate between lamps of the same wattage, but which have different pin configurations (see base reference below).
  • Additional information, such as color, may be added after a further "/" separator.

Incandescent Lamps - Base Identification

Halogen Lamps - Base Identification

Compact Fluorescent Lamps - Base Identification

Stage and Studio Lamps - Base Identification

Miniature - Base Identification

Sealed Beam - Base Identification

Projection Lamps - Base Identification

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