Choosing the wrong plugs and sockets bad luck with the timing

David Davies

When the private house Holly Hill was converted into Fulmer’s laboratories, new electrical fittings had to be installed. It turned out that 1946 was a bad year to make this change.  Holly Hill was converted into Fulmer’s laboratories in 1946 and the Foundry building was either built in the same year or, more likely, in the first half of 1947.

We don’t know what services were installed at Holly Hill before the conversion. We know that there was no mains gas supply⁽¹⁾ but a property of this type would almost certainly had electric lighting and power, probably with the usual pre-war BS 546 sockets but possibly with earlier types. What we do know is that additional services, including three-phase 430V supplies, had to be laid during the conversion.⁽²⁾

During the Second World War, in 1941 The Directorate of Post-War Building was established in the anticipation that a major programme of reconstruction would be necessary after the war. A set of committees was tasked with reporting on various aspects of building and construction. One of these, the Electrical Installations Committee, reported in 1944.  This committee proposed that a completely new socket-outlet and plug should be adopted as the “all-purpose” standard. Safety aspects were an important issue. Socket contacts should be protected by shutters or other like means. Each plug or socket should be individually fused.
D&S design was unique in that the line pin in the plug was a screw-in cartridge fuse. Changing the fuse was therefore easy; you just unscrewed it from the plug and screwed in a replacement. There was no need to dismantle the plug. An unnerving hazard was that occasionally the fuse would work loose and, on unplugging the equipment you would be left with the live fuse projecting from the socket. You had to remember to remove it with insulating pliers!

In the following year, 1947, British Standards Institution chose the rival MK design for its standard BS 1363. This remains the current standard to this day.
As BS 1363 fittings became widely adopted, Fulmer found supplies of D&S plugs and fuses difficult to source. At Fulmer, the cannibalizing practice grew up of “borrowing” a fuse from any neighbouring piece of equipment not in use. This led to irritation and delay and eventually to the ad hoc replacement of DS sockets by the new BS 1363 pattern.  We are now not sure which type of sockets were fitted in the four 1950s buildings but by the time the 66 building was built Fulmer had certainly adopted the modern standard.

Fulmer was not the only organization to make the wrong choice; another was the BBC.

(1) “The engineer” (July 11 1947), in a report on the official opening of Fulmer on July 2 1947
‘Gas mains have been laid in anticipation of a local supply and, meanwhile, use is being made of ” Calor ” gas fed to all essential points from individual gas cylinders.’

(2) ibid
‘The Institute is provided with three-phase electric power at 50 cycles frequency and 415 volts line voltage, and in most laboratories 230 volts single-phase supply is also available. Direct current for corrosion tests, etching, polishing and engineering laboratories is furnished by rectifiers.’

This article uses material from the Digital Museum of Plugs and Sockets  and from Wikipedia