GU24 connector

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Compact fluorescent light bulb with GU24 connector

A GU24 connector is fitting for compact fluorescent light bulbs (CFL) that uses a bayonet mount-like twist-lock bi-pin connector instead of the Edison screw fitting used on many incandescent light bulbs. The GU24 fitting allows the overall length of the bulb to be shorter since the threaded base is eliminated.


  • Use of the GU24 fitting provides compliance with a 2008 ruling by the California Energy Commission under Title 24 (California Building Standards Code) to require high-efficiency lighting on all residential remodels and new construction. The GU24 fitting maintains the energy efficiency of the light by preventing an occupant from using an incandescent bulb instead of a CFL. Adapters to use incandescent bulbs in a GU24 fitting are illegal in the State of California as they would be a fire hazard in fixtures designed for the lower heat output of a CFL bulb.[1]


  • The GU24 fitting is not compatible with older light fixtures designed for incandescent bulbs, whereas a CFL with an Edison screw fitting is a direct replacement for an incandescent bulb.
  • Requires proper alignment to install, but most bulbs/sockets obscure the pin orientation.
  • No 3-way lamp support.
  • Creates more E-waste as functional GU24 or Edison screw lamps/fixtures are forced into obsolescence.
  • Lamps are not more efficient than an identically spec'd Edison Screw Lamps.
  • Will maintain a price premium while they are mandated in a minority of jurisdictions.


  1. ^ GU24: New Pin-Base for CFLs, LEDs, Environmental Building News, October 1, 2011