G4 miniature bi-pin base
G4 is a tiny 12V two-pin capsule base with straight wire pins spaced 4mm apart.
Exact specs
| Designation | G4 (miniature bi-pin) |
|---|---|
| Pin spacing | 4 mm (center-to-center) |
| Pin form | Straight wire pins |
| Voltage | 12V AC/DC (low voltage) |
| Typical wattage | 1W–20W equivalent |
What fixtures commonly use it
Marine and RV reading lights, decorative accent lamps, boat interior lighting, and small pendant lamps often use G4 capsules.
What it's interchangeable with
G4 LED capsules replace G4 halogen capsules in the same 12V applications. Verify LED compatibility with DC systems as some G4 LEDs are DC-only.
What it's NOT interchangeable with
G4 is not equivalent to G9, which is a mains-voltage loop-pin design with 9mm pin spacing. Do not use G9 bulbs in G4 sockets or vice versa.
Common mistakes
- Confusing G4 with G9 by appearance — both are small capsule types but voltage is different.
- Plugging G4 capsules into 120V/240V circuits without a 12V transformer.