In that case, if it trips again with nothing plugged into the sockets, the cause must be a nuetral to earth fault on the circiut wiring.
If so the cable will need to be insulation tested and connections at all sockets and the CU will need to be checked out.
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And ask the electrician to do a ramp test on the RCD to see what current it actually trips at.
recurred and it has happened with nothing plugged in to the sockets that t he RCD covers. We have had another electrician look at it and he cannot fin d any fault. However, since he switched the RCD back on it has not tripped and that was on Monday, but sometimes it can go days without tripping.
NT
Got some of the hallmarks of a possible Neutral Earth Short.
Switch everything off thats -Everything- in the house.
Any trips for say a few minutes?. If no then switch on something fairly hefty like a electric fire or fan heater if a trip follows quite quickly then almost certainly a neutral earth fault.
Other good interment causes are electric cookers leakage from the heater element to the metal ring part. Also electric immersion heaters all can do this a little while after being switched on and finally washing machines and dishwashers.
Try if you can isolating those possibles whilst running some other appliances and see if that shows anything up.
They can be a right PITA to find sometimes. I presume the electrician involved disconnected the incomers to the consumer units and did some resistance tests from line and neutral to earth all should be effectively open circuit...
Be careful with that line of thought as some current must -flow thru- the RCD in order to make it trip out. If nothing was flowing anywhere then no trip...
Consider if there was a full neutral - earth short then if there was nothing connected then where would the current come from to flow in to the RCD on the live line?.
The current that would flow back thru the RCD is now being diverted to earth and isn't --balancing-- the current flowing into the RCD....
The way I traced mine was to do an RCD ramp test with everything dis-connected and see what the trip current was.
Then I repeated with everything connected and found it had dropped from
30ish mA to about 10mA.It did not take long with plugging and unplugging stuff to isolate it to the combi microwave that must have had a bad element.
One could do this with a well constructed (insulated and mains rated) switchable resistance box between L-E.
If each resistor adds another 5mA of leakage and you have another set at
2.5mA leakage, you can ready-reckon the trip level of the RCD with and without load.
To the OP. I found this article with many suggestions...
...Ray.
ecurred and it has happened with nothing plugged in to the sockets that the RCD covers. We have had another electrician look at it and he cannot find any fault. However, since he switched the RCD back on it has not tripped an d that was on Monday, but sometimes it can go days without tripping.
If it's a neutral-earth connection that causes the RCD to trip, whether it trips depends on the neutral line volts which I believe depends on the thre e phase load balance down the rest of your street. This varies from time t o time and mine was sometimes several volts measured to earth. Had the problem with a neutral wire crushed in the metal housing of a wall lamp that would be OK for weeks then decide to trip out.
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