I have a problem on which I have been stuck for the past three weeks. One of my clients have been experiencing earth leakage trips intermittently since the beginning of April. It all started when their gardener washed the walls of their home. I investigated and found that the problem initially "wandered" between circuits, in other words, the earth leakage unit would trip and would not reset until you switch off "Plugs circuit breaker 5" for instance. The next time it trips, it would reset only once you switch off circuit breaker 7.

I disconnected all the neutral conductors and carried out an insulation resistance test on all of the circuits/cables. Initially, I picked up a fault (24kΩ) on one of the cables between Live and Earth. I disconnected this cable completely and all the other cables tested clear (>600MΩ).

The problem did not subside however and rather seems to have stabilised to one circuit, feeding 3 plugs and 3 lights, all located in one room. The reason why I say this, is that when the earth leakage trips, it won't reset until they switch this specific circuit breaker off. I have tested the circuit a number of times and it tests clear, yet every time it starts to rain, the earth leakage trips. I though it would be a fruitful exercise to simulate rain by spraying the area where the cables run with a hose pipe and yet nothing happens. I have opened every socket outlet, light and junction box to assess for water ingress, yet everything is dry.

I have replaced the earth leakage unit twice. It trips at 25mA with all the circuit breakers switched off and as I switch them on, the sensitivity gradually decreases until it finally reaches a tripping current of 6mA with all circuit breakers switched on. At this point I can't even plug my earth leakage tester into the socket outlets and it trips the earth leakage. There are 14 circuit breakers connected to this earth leakage unit.


This fault is driving me insane! Is there anyone who has had a similar experience and could shed some light on this for me, please?

Thanks.