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I got called out to house a few days ago with the main rcd tripping when they turned the hot tap on with the combi firing up.They had only just had the new boiler fitted and the tripping had started straight after it was installed.
I IR'd the boiler circuit(which was wired on its own 16amp breaker) and got>200 megohms across live,neutral and earth.
I then tested the rcd with trip times of 28ms and 10ms for x1 and x5.The ramp test gave 27ma trip.
I then tested the remaining circuits and all of them were clear except one which had a live and neutral to earth reading of 4 megohms.
I had a look at the boiler spur connections and inside the boiler.All perfect.
So,seeing as only one circuit(downstairs sockets) was generally low i moved that circuit over to the non rcd side and fitted a 30ma rcbo to see if that would trip.
I got a call the following day to say that the main rcd was still tripping.
So i went back and reinstated the down sockets back onto the rcd side and moved the boiler circuit over onto the rcbo.
I was expecting a call to say that the rcbo was now tripping and at least i would be able to narrow it down as to which circuit was causing it.
It has now been a few days and neither the main rcd or the rcbo has tripped.
Any ideas why this could be?
One theory is that some electronic circuit in the boiler was upsetting the main rcd and by moving it to a different type and make it now doesn't trip that breaker?
The other theory is the cumulative leakage of the socket circuit and the boiler supply was enough to trip the rcd?
Because the fault is intermittent and the readings are generally above the rcd tripping threshold then this is why i have had to revert to trial and error to find the which circuit is causing it?
Anyone else had this sort of fault before?
I IR'd the boiler circuit(which was wired on its own 16amp breaker) and got>200 megohms across live,neutral and earth.
I then tested the rcd with trip times of 28ms and 10ms for x1 and x5.The ramp test gave 27ma trip.
I then tested the remaining circuits and all of them were clear except one which had a live and neutral to earth reading of 4 megohms.
I had a look at the boiler spur connections and inside the boiler.All perfect.
So,seeing as only one circuit(downstairs sockets) was generally low i moved that circuit over to the non rcd side and fitted a 30ma rcbo to see if that would trip.
I got a call the following day to say that the main rcd was still tripping.
So i went back and reinstated the down sockets back onto the rcd side and moved the boiler circuit over onto the rcbo.
I was expecting a call to say that the rcbo was now tripping and at least i would be able to narrow it down as to which circuit was causing it.
It has now been a few days and neither the main rcd or the rcbo has tripped.
Any ideas why this could be?
One theory is that some electronic circuit in the boiler was upsetting the main rcd and by moving it to a different type and make it now doesn't trip that breaker?
The other theory is the cumulative leakage of the socket circuit and the boiler supply was enough to trip the rcd?
Because the fault is intermittent and the readings are generally above the rcd tripping threshold then this is why i have had to revert to trial and error to find the which circuit is causing it?
Anyone else had this sort of fault before?