History
The 1934 edition of the standard, titled "Two-Pole and Earthing-Pin Plugs and Socket Outlets" superseded BS 372 "Side-Entry Wall Plugs and Sockets for Domestic Purposes" Part II, which was published in 1930. BS 546:1934 clause 2 specifies interchangeability with BS 372 Part II which includes the same four plug and socket sizes. BS 372 Part II had itself superseded BS 317 "Hand-Shield and Side Entry Pattern Three-Pin Wall Plugs and Sockets (Two Pin and Earth Type) published in 1928. BS 372 Part II states that there are only minor alterations from BS 317. (BS 372 Part I was a standard for two pin non-earthed plugs which were never specified by BS 546.)
Although still permitted by the UK wiring regulations, these sockets are no longer used for general appliances. Some of the varieties remain in use in other countries and in specialist applications such as stage lighting.
Prior to the adoption of (what was to become) BS 546 as a standard, there were around two dozen different types of power socket used in different cities throughout Britain. The development of the National Grid in the late 1920s provided the impetus for greater standardisation of voltages, frequencies and plug types.
The sockets were not shuttered when BS 546 was in common use domestically in the UK. The current revision of the standard does specify shutters similar to those of BS 1363. Current UK wiring regulations require socket outlets installed in homes to be shuttered.
Read more about this topic: BS 546
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