I'm stumped on this one. My mate has a two way garage board in his garage. Circuit 1 is lighting, circuit 2 is 3 sockets on a radial. Lighting works fine. Sockets trip main RCD in DB when switched on. 3 sockets are now disconnected. Tried to reset 16A MCB (for radial circuit) and still trips RCD. So... Thought, simple, fault is on cable between DB and first socket. Disconnects live from out of top of MCB and it stays on. But.... When I push cable into top of MCB again, (even though the MCB is switched off), the lights go out (but don't trip) and arc like crazy from the bottom of the MCB). Bearing in mind this cable goes from the DB to the first socket and is disconnected at both ends!! Only things I haven't done is disconnect the neutral as well whilst trying to connect it back in. I realise this is an absolute headache to read. But if you manage to understand, could you give your opinions. Much appreciated, Lee