BS 1363 (Type G)
Main article: BS 1363
BS 1363:1995 “13 A plugs, socket-outlets, adaptors and connection units” is used in the United Kingdom, the Republic of Ireland, Hong Kong, Cyprus and other countries. Compatible standards are IS 401 and IS 411 (Ireland), MS 589 (Malaysia), SS 145 (Singapore), and SASO 2203 (Saudi Arabia).
An earthed(top) and an Unearthed BS1363 Plug
This plug, commonly called a 13 A plug or 13 amp plug, has three rectangular pins forming a triangle. Line and neutral are nominally 4 by 6.35 mm (0.157 by 0.250 in) and 17.7 mm (0.697 in) long, on centres spaced 22.2 mm (0.874 in) apart. 9 mm (0.354 in) of insulation at the trailing ends of the pins prevents accidental contact with a bare connector while the plug is partially inserted. The earth pin is nominally 4 by 8 mm (0.157 by 0.315 in) and 22.7 mm (0.894 in) long.
The plug has a 1 in (25.40 mm) long fuse to protect the appliance flexible cable from overload. British wiring standards allow up to 32 A ring main circuits, so circuit protection of the fixed wiring cannot protect relatively small flexible cable conductors. Plugs and sockets are wired so that the fuse opens the line wire. The same convention is used for all British sockets connected directly to “mains” wiring.
UK wiring regulations (BS 7671) require sockets in homes to have shutters over the line and neutral connections to prevent the insertion of objects other than electric plugs. On Class II appliances, the earth pin is often plastic and serves only to open the shutters and to enforce the correct orientation of line and neutral pins. Opening the shutters with a screwdriver to insert other plugs may be dangerous if the plugs do not have a fuse or do not fit properly.
BS 1363 plugs and sockets started appearing in 1946 and BS 1363 was first published in 1947. By the end of the 1950s, it had replaced the earlier BS 546 in new installations, and by the end of the 1960s, most earlier installations had been rewired to BS 1363 standards. Sockets usually include switches on the line side for convenience and safety.
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