BS 1363 is a British Standard which specifies the most common type of domestic AC power plugs and sockets that are used in the United Kingdom, Cyprus, Hong Kong, Ireland, Malta, Malaysia, Singapore, and many former British colonies. Of these, Ireland, Malaysia and Singapore have equivalent standards—IS 401 & 411, MS 589, and SS 145, respectively. The standard was introduced in 1947, shortly after the Second World War, as part of a new standard for electrical wiring in the United Kingdom.

Trading standards legislation in both the UK and Ireland requires that all domestic electrical goods sold in either country should be fitted with a BS 1363 or IS 401 (as applicable) plug.

Other plug types used in the same area include IEC 60309, only used in industrial and some outdoor applications, and BS 546, limited to old installations and specialised applications where either the BS 1363 plug is unsuitable or where mateability with the standard variety is not desired (for example, where lamps are controlled by a switch or dimmer

Top: a typical moulded BS 1363 plug, showing the fuse access from the underside of the plug. Bottom: a typical rewireable plug; the large central screw releases the cover, allowing access to the terminals and also the fuse