David wrote:
Hi All,

In my house there is a consumer unit with RCD. It has 5 circuits on it
(1 cooker, 2 ring mains, 2 lighting). Taking off the fronts of sockets
these appear to be correctly connected on a ring main. However, I can
only see 5 wires going into the consumer unit - I would have thought
there'd be 9, assuming that both sockets and lighting were on ring
mains?

Am I being an idiot? Why would anyone bother wiring up sockets on a
ring main and then not complete the ring back at the consumer unit? Or
is it possible for example for only the 'live' ends of the ring to go
to the consumer unit, with the other 'earth' end of the ring being
connected to the main supply (where I can't see it)?

If it really is a ring circuit then both ends must come back to the
same 32 amp MCB in the CU.


Possibility 1
Are you sure the socket circuits are supposed to be ring mains? It's
not mandatory you know and there are perfectly acceptable alternatives.
Are the MCBs on the socket circuits 32 amp?

Possibility 2
Are you sure you can see all the wires coming out of the CU? There
may be some going straight back into the wall it's mounted on. Have
you taken the cover off the CU to see how many wires go into each MCB?

Possibility 3
It really has been mis-wired.


--
Chris Green