Twist & lock base guide

GU24

Two-pin twist lock

GU24 has two pins set 24 mm apart and locks with a twist. It was designed to prevent the use of inefficient screw-in lamps in dedicated fixtures.

Reviewed August 12, 2026
24 mm pin spacingNominal measurement · drawing not to scale
Connection
Twist & lock
Electrical context
Typically 120 V U.S. fixtures
Also called
GU24 twist-and-lock, Bi-pin twist lock

How to identify GU24

  1. Look for two short pins projecting from a flat plastic base.
  2. Measure roughly 24 mm between pin centers.
  3. Push into the socket and rotate to lock.

Where it is commonly used

Energy-code fixturesCeiling lightsUtility fixturesApartments

Common use is a clue, not proof. The fixture label and model documentation take priority over a visual match.

Bulb shapes sold with this base

You may see these shapes with a GU24 base. The base code does not guarantee the bulb width, length, beam angle, or clearance.

A19Spiral CFLIntegrated LED

Before you buy a replacement

  • GU24-to-E26 adapters may defeat the fixture's original certification intent.
  • Confirm the fixture's ballast or direct-wire requirements.
  • Check overall bulb height inside shallow covers.