AC power plugs and sockets: British and related types

Plugs and sockets for electrical appliances in the United Kingdom originated in the 1870s and were initially two-pin designs. These were initially sold as a mating pair, but gradually standards arose to enable the interchange of compatible devices.

In the United Kingdom, British Standards lists three types of socket-outlet systems primarily for domestic use:

The fuse-in-plug universal polarised maximum 13 A BS 1363. This family of accessories has one universal plug having a user replaceable fuse to suit the needed amperage of the appliance flex and appliance;

The unfused polarised BS 546. This family of socket-outlets has four plug types of differing sizes: 2 amps, 5 amps, 15 amps, and 30 amps;

The BS 4573 two-pin unpolarised socket and plug. This is a niche application socket-outlet used primarily for shavers and rechargeable toothbrushes.

A distinctive characteristic of the one BS 1363 socket-outlet and the BS 546 socket-outlet family are protective safety shutters behind the socket holes, and optional socket switches.

The BS 1363 universal socket-outlet plug differs from the BS 546 family by incorporating square pins rather than round pins and a user replaceable fuse from 1 A to 13 A.

The BS 1363, universal 13A socket-outlet system and connection units is the dominant type of single-phase socket-outlet system used in the United Kingdom, having only one plug type. The BS 546 socket-outlet family of four types tends to be used for niche applications, although the 5 A version has had a resurgence in switched lighting circuits. The BS 546 30 A plug has near disappeared from the UK market due to poor demand.