Museum of Plugs and Sockets logo, small Bayonet Cap (B22d-2)
plugs, outlets and adapters
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BS 546
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 phased out


Bayonet lampholder with 5A 2pin outlets Bayonet adapter with swich BC lighting plug Bayonet Cap plug

BC plug, exploded view

1 B22d-2* bayonet lamp holder with two BS 372 Part I outlets.   {JM}
* B = Bayonet; 22d = diameter in mm; 2 = double contacts. This type is also known as BC = Bayonet Cap.
Brand name: Anchor, a large Indian plug, socket and switch manufacturing company. Bayonet light bulb mounts are the standard fitting in - among others - India and Bhutan. India uses plugs according to IS 1293, which is derived from BS 546.
2 Two-way BC adapter with switch (red).
3 BC lighting socket plug in accordance with the BS 52 standard. The plug fits in a B22 bayonet lamp holder (see nos. 1 and 2).
The donor of this plug - David Fisher - has added the following comment:
Originally bayonet socket were used in the UK for ‘Lighting’, whereas BS 546 sockets were meant for 'Power'. Lighting and Power were charged at a different tariffs. So everybody plugged the electric iron into the light socket to do it on the cheap. Bearing in mind that B22d-2 has no earth connection, it was a potentially lethal method of saving money.
4, 5 BC adapter plug that is composed of two parts: an outlet that fits in a B22d-2 lamp holder (bottom right) and a standard 2-pin 5A BS 372 Part I plug (bottom left). Instead of this plug each other 2-pin 5A, or shaver plug can be used. Image no.5 shows and exploded view of this ingenious device.   {DF}


Bayonet cap adapter plug with variable pin spacing
Bayonet cap adapter plug with variable pin spacing

6, 7 Adapter plug with two pins (5 mm diameter) which spacing is adjustable between 15 and 24 mm. Pins are connected to a B22d-2 bayonet outlet. The adapter fits a variety of outlets, but it is questionable whether sockets have existed that could accept the adapter with 5 mm pins positioned only 15 mm apart. Characteristics of BS 546 plugs/sockets are given on the BS 546 main page.
The adapter has been designed by The General Electric Company Ltd, London and William Manchester of Union Works, North Wembley, Middlesex. U.K. Patent no. 251068-A for 'An improved electric connector or adapter' was published on April 29, 1926. {PC}


Find more examples of bayonet cap material on the page devoted to classic South African plugs and sockets.


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BS 546
D i g i t a l   M u s e u m   o f
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P l u g s   a n d   S o c k e t s
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Bayonet lamp