I'm not an electrician, but have a fair DIY understanding of single phase electrical wiring.

A lot of building and electrical work was done on my partner's house immediately before she moved in. All the lights/plugs etc work, but she's had intermittent tripping that I tried to fix this weekend. I found a rats nest of wires in the DB, as well as loose wires that I assume went to plugs/lights etc that were removed in the rebuild.

I was hoping to fix the obvious faults and then bring in a qualified pro to check / fix and sign off on the CoC.

Here's my (very confusing) problem. The house has a plug circuit that has been wired to bypass Earth leakage. It trips the ELCB as soon as I try connect it correctly. I followed the instructions AndyD posted to track down EL problems with no luck, but here is the thing: as long as the circuit bypasses the ELCB the circuit works EVEN IF all the neutrals are disconnected. I even disconnected the mains neutral in the DB and the circuit STILL works.

Is there something obvious I can look for, or is this clearly a job for a qualified electrician?

Many thanks for any ideas.