The Natural Philosopher wrote:
John wrote:

"DrJones" wrote in message
oups.com...

I am installing electric in my garage. I have used 4mm T&E (about
25m)
inside which is protected by an RCD on the main consumer unit. The
RCD
also protects the socket circuit for the house. I am using a 16amp
MCB
for the cable. As soon as I test the cable the RCD on the CU
trips,
the MCB is unaffected. I then wired the T&E to the MCB used for the
house sockets, once again the RCD trips. I thought it could be the
cable so I replaced that but after testing it happened again. Any
ideas?


Not enough information to offer any opinion at all, but probably
damaged
insulation or a connection error. Ideally a megger should be used
to find
the problem/ check the insulation at 500v but otherwise get a
=A34.99 test
meter from Maplin and isolate the fault by opening the ring circuit
at the
farthest point and check backwards for shorts on each half of the
ring.

What do you mean by 'testing'. It sounds like the test procedure
itself=20
may be teh problem.

maybe the old tongue test?

NT