RCD Tripping

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 £4.99 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.

john

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

Get an electrician in. There appear to be so many problems with how you've done this so far that I'm reluctant to advise further.

(At the very least, read a copy of the On-Site Guide and learn what "test" means)

Sounds like your house CU is a split load unit where the RCD protects some of the circuits but not all. If this is the case then you probably have the neutral of then new circuit connected to the non RCD protected neutral bus bar.

Depends a bit on what you are doing to test it though...

Have you followed the test procedure in the On-Site Guide?:

trips,

maybe the old tongue test?

NT