B22d

B22d is a lamp base designation used for a Bayonet Cap type with a 22 millimetre diameter and a double-contact bottom configuration. The B22 family is standardized in lamp-cap and holder specifications, and the “d” suffix signifies that the base provides two electrical contacts at the bottom, in contrast to a related “B22s” type that uses a single bottom contact. The base is defined by the presence of two opposite bayonet lugs on the sides of the base, which engage with matching slots in the lampholder; a push-and-twist action locks the bulb in place and establishes electrical connection.

Usage and compatibility: B22d bulbs are designed for mains voltage in many markets that historically adopted the Bayonet Cap system, particularly in the United Kingdom, Ireland, Australia, New Zealand, and parts of Asia and Africa. They are less common in North America, where screw-base luminaries (such as E26/E27) are dominant. Bulbs with B22d bases come in various technologies, including incandescent, halogen, compact fluorescent (CFL), and LED forms, all manufactured to fit the 22 mm bayonet base and to operate at the appropriate mains voltage for the region.

Considerations: When replacing bulbs, it is important to match the base type (B22d vs B22s or other bayonet variants) and verify the voltage and wattage rating of the fixture. Some LED replacements are offered specifically in B22d, and adapters are generally not recommended as they can compromise fit and safety.

See also: Bayonet cap, B22, BA22d, IEC 60061.