Adaptors enable more than one plug to be put into a single socket, or allow a plug or plugs which are of a foreign type to be used in a UK socket. Adaptors which fit a BS 1363-2 socket and accept British plugs are required to meet BS 1363-3:2016, specification for adaptors. These adaptors MUST be shuttered.
British Standard BS 8546:2016 Travel adaptors compatible with UK plug and socket system has been in force since April 2016. It was introduced because UK authorities are concerned about the number of unsafe travel adaptors on the market. For more information on BS 8546, see the following sources: BSI, Electrical Safety First, Nemko and Intertek, . Adaptors which fit a BS 1363-2 socket and accept non-UK plugs MUST be fitted with a fuse conforming to BS 1362, MUST conform to the pin dimensions of a BS 1363-1 plug, and MUST provide an earth connection. They are required to conform to BS 8546:2016 . Adaptors which accept BS 1363-1 plugs and fit in non-UK sockets MUST be shuttered and must also conform to BS 8546:2016.
It is not uncommon to find travel adaptors placed on the UK market, particularly through website such as amazon.co.uk and ebay.co.uk, which do not meet the required standards and are therefore illegal. We list some of the illegal and unsafe adaptors removed from the market in recent years on our RAPEX page.