On 20/09/2020 09:11, Jeff Layman wrote:
Fortunately not mine!

A friend just told me "I have just replaced a single electric socket in
our lounge with a switched double. In order to stop the supply, I had to
switch off two trip switches at the same time." That didn't sound right,
or safe.

DIYWiki notes: at (http://wiki.diyfaq.org.uk/index.php/Ring_circuit):
"The ring circuit cable starts at the consumer unit (fusebox]), visits
each socket in turn, and then returns to the consumer unit. The 2 cable
ends at the CU are connected together in all modern rings, and supplied
by one fuse or MCB."

That confirms there should be one MCB, but I note the use of "...in all
modern rings...". Does that mean there might have been two fuses or MCBs
in early rings? I think his house was built around 1980.

Not in the 80's...

There was a time when the ring circuit was first introduced in the 40's
that it may have been formed from two 15A fused radials, that were
joined in the middle so to speak. It was a way of creating a more
versatile circuit that could be used for house heating etc, at a time
(i.e. just after WWII) when materials were in short supply.

So in summary, he has some faulty wiring.

--
Cheers,

John.

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