In message , Lurch
writes
Ring mains were originally introduced as an easy way of converting the
very common 15A radial circuit into a 30A circuit for being able to
plug new fangled electric heaters and such like in.

So what was wrong with plugging the heaters into the lamp sockets with
those lovely Bakelite bayonet cap plugs?

--
Clive Mitchell
http://www.bigclive.com