Friends of mine have a circuit where the RCD trips but only after prolonged rain. There are a number of garden and security lights on that circuit so I very much suspect there is a junction box where water gets into it.
There are two challenges:
- Find where the cables are buried.
- Find the 'wet' junction box.
I assume this is a problem which electricity distribution companies have to cope with more often and that there is a well know solution.
For 1: Find where the cable are buried.
I was thinking to put an RF signal on the cable and then use an antenna/coil to find where they are. (Of course first disconnect it from the mains)
For 2: - Find the 'wet' junction box.
I was thinking of borrowing a Time-domain reflectometer (Or set one up with a pulse generator and a scope). But I have no idea how accurate those are, especially with multiple junction boxes upstream.
I am hoping for somebody with practical experience or knowledge/tips how/if these methods would work?
I have a scope, pulse generators, multi meters, a spectrum analyzer and a small electronic lab available.