K
Knobhead
A bit of socket / plug history, some of it plagurised from Wikki, some from memory, some from personal experience.
In 1941 Lord Reith, the then minister of Works and Planning, instigated the establishment of a series of committees to investigate and report on the problems likely to affect the peace time rebuilding of Britain. One of these, the Electrical Installations Committee, was charged with the study of all aspects of electrical installations in buildings. Convened in 1942, they reported in 1944.
One of the most far reaching recommendations, still in effect in the 21st century, was the introduction of the ring main, where, instead of each socket being individually wired, a cable was brought from the fuse or circuit breaker in the distribution board and wired in sequence to a number of sockets before being taken back to the distribution board and wired to the same fuse or circuit breaker. This provided considerable savings in the copper required to wire the circuit. Since the fuse or circuit breaker had to be rated for the maximum current the ring could carry 30A, it was required that the plugs used to connect to the ring each contained their own fuse rated for the appliance that it connected.
The plug and socket system defined in BS 1363 is a result of another of the report's recommendations. Britain had previously used a combination of 5 amp and 15 amp round pin sockets, where each had to be wired to the distribution board where it would be provided with its own fuse. In a supplementary report, published as an appendix to the main report (July 1944), the committee proposed a completely new socket outlet and fused plug should be adopted as the "all-purpose" domestic standard. A number of technical details were required of the new standard, first of which was that “To ensure the safety of young children it is of considerable importance that the contacts of the socket-outlet should be protected by shutters or other like means, or by the inherent design of the socket outlet.”[SUP] [/SUP]This requirement for a new system of plugs and sockets led to the publishing in 1947 of "British Standard 1363 : 1947 Fused-Plugs and Shuttered Socket-Outlets
Off the beaten track
MK anti-flash socket (2-pin 5 and 15A versions) that has shutters covering the inserts as soon as the plug is withdrawn. This is marketed more as an arc-reduction device (they weren’t switched) than a safety shutter however.
Dorman Smith plugs and sockets. These were very common in council installations. The Dorman Smith system had an interlocked switch. Inserting a plug unlocked the switch, turning the switch on locked the earth pin in to the socket so it couldn’t be withdrawn. (I can remember the Dorman Smith system as a kid, my aunt’s house had them).
Wylex plugs and sockets had a tubular central pin with the flat N pin in line and the L offset. The fuse internal to the plug. The 15A plugs had a novel feature, you could put a 5A plug in to the top of it. (Who needs adaptors). One of the electricians I served my time with had these in his house, he wouldn’t change to the “new fangled” 13A sockets!
Bellmoss Pebbles didn’t take off for domestic use, but did in industry. The fuse was the live pin it’s self. Great if the pin snapped in the socket (as happened all to often). If you spent the few bob more you could have them switch interlocked like the Dorman Smith system. They were a pain in the a**e!
In 1941 Lord Reith, the then minister of Works and Planning, instigated the establishment of a series of committees to investigate and report on the problems likely to affect the peace time rebuilding of Britain. One of these, the Electrical Installations Committee, was charged with the study of all aspects of electrical installations in buildings. Convened in 1942, they reported in 1944.
One of the most far reaching recommendations, still in effect in the 21st century, was the introduction of the ring main, where, instead of each socket being individually wired, a cable was brought from the fuse or circuit breaker in the distribution board and wired in sequence to a number of sockets before being taken back to the distribution board and wired to the same fuse or circuit breaker. This provided considerable savings in the copper required to wire the circuit. Since the fuse or circuit breaker had to be rated for the maximum current the ring could carry 30A, it was required that the plugs used to connect to the ring each contained their own fuse rated for the appliance that it connected.
The plug and socket system defined in BS 1363 is a result of another of the report's recommendations. Britain had previously used a combination of 5 amp and 15 amp round pin sockets, where each had to be wired to the distribution board where it would be provided with its own fuse. In a supplementary report, published as an appendix to the main report (July 1944), the committee proposed a completely new socket outlet and fused plug should be adopted as the "all-purpose" domestic standard. A number of technical details were required of the new standard, first of which was that “To ensure the safety of young children it is of considerable importance that the contacts of the socket-outlet should be protected by shutters or other like means, or by the inherent design of the socket outlet.”[SUP] [/SUP]This requirement for a new system of plugs and sockets led to the publishing in 1947 of "British Standard 1363 : 1947 Fused-Plugs and Shuttered Socket-Outlets
Off the beaten track
MK anti-flash socket (2-pin 5 and 15A versions) that has shutters covering the inserts as soon as the plug is withdrawn. This is marketed more as an arc-reduction device (they weren’t switched) than a safety shutter however.
Dorman Smith plugs and sockets. These were very common in council installations. The Dorman Smith system had an interlocked switch. Inserting a plug unlocked the switch, turning the switch on locked the earth pin in to the socket so it couldn’t be withdrawn. (I can remember the Dorman Smith system as a kid, my aunt’s house had them).
Wylex plugs and sockets had a tubular central pin with the flat N pin in line and the L offset. The fuse internal to the plug. The 15A plugs had a novel feature, you could put a 5A plug in to the top of it. (Who needs adaptors). One of the electricians I served my time with had these in his house, he wouldn’t change to the “new fangled” 13A sockets!
Bellmoss Pebbles didn’t take off for domestic use, but did in industry. The fuse was the live pin it’s self. Great if the pin snapped in the socket (as happened all to often). If you spent the few bob more you could have them switch interlocked like the Dorman Smith system. They were a pain in the a**e!
