Re: When were ring mains introduced in domestic housing?
13 amp sockets were only meant to be installed on 50 cycle AC circuits at 230/250 volts.
So the older round pin sockets were still required, even in new houses, if the supply was DC or non standard AC.
DC mains largely "went out with the war" at least for new supplies and most new housing estates were served with standard voltage AC.
However some new homes were built not in large estates but on bomb sites in existing urban areas, these might well have had DC or non standard AC supplies.
The Weir report into the future of electricity supply recommended that all new electrification schemes should be 50 cycles AC.
Domestic supplies to be single phase, 2 wire, 240 volts with an earthed neutral. Normally obtained from 3 phase, 4 wire main at 240/415 volts.
Single phase, 3 wire systems at 240/480 volts were allowed as an alternative.
Additions, extensions, and improvements to existing DC or non standard AC systems were allowed, but "new schemes" for public supplies had to be standardised.
One merit of the 13 amp system, in the early days thereof, was that the presence of a 13 amp socket SHOULD denote an AC supply of standard voltage and frequency, to which an unskilled person could connect any appliance with a matching plug.
The presence of other types of socket outlet, in an unfamiliar building, might make enquiry or testing prudent before use.
|