Bayonet mount

A bayonet mount (mainly as a method of mechanical attachment, such as fitting a lens to a camera using a matching lens mount) or bayonet connector (for electrical use) is a fastening mechanism consisting of a cylindrical male side with one or more radial pegs, and a female receptor with matching L-shaped slot(s) and with spring(s) to keep the two parts locked together.

The bayonet mount is the standard light bulb fitting in the United Kingdom and in many countries that were members of the British Empire including Australia, Hong Kong, Fiji,[1] India, Pakistan, Sri Lanka, Ireland and New Zealand, parts of the Middle East and Africa and, historically, in France and Greece.

To disconnect, the two parts are pushed together to move the pin out of the "serif" while twisting in the opposite direction than for connecting, and then pulling apart.

It is possible to push down the connector and rotate it, but not far enough to engage and lock; it will stay in place temporarily, but accidental disconnection is very likely.

[2] This type of fitting was later used for soldiers who needed to quickly mount bayonets to the ends of their rifles, hence the name.

The bayonet light bulb mount is the standard fitting in many former members of the British Empire[citation needed] including the United Kingdom, Australia, India, Ireland, and New Zealand, Hong Kong, as well as parts of the Middle East and Africa (although not Canada, which primarily uses Edison screw sockets along with the United States and Mexico).

First developed by St. George Lane Fox-Pitt in the UK and improved upon by the Brush Electric Company from the late 1870s onward, standard bulbs have two pins on opposite sides of the cap;[3][4] however, some specialized bulbs have three pins (cap designation B22d-3) to prevent use in domestic light fittings.

Older railway carriages in the UK also made use of a 3 pin bulb base to discourage theft.

The entries from the table below pertain to IEC 60061 "Lamp caps and holders together with gauges for the control of interchangeability and safety"[5] and to DIN 49xxx.

A similar concept existed in BS 7001 as the slide-in “luminaire-supporting coupler” (LSC), but its prominence is unknown.