Electrical problem - Earth tester tripping at CU
Discussion
I've just had a call from my brother who is replacing his kitchen.
He has had to move a socket as part of the refit and he is using a Martindale EZ150 socket tester to check the socket wiring. Apparently before he did anything the tester worked fine and showed all good, low Earth resistance.
After moving the socket the tester does its self test and then the CU trips. Asking him about what they've done he swears that moving the socket and moving an earth bond is the only change.
The kettle apparently works fine plugged in anywhere so they still have tea
He says that the trip switch is 30mA and that nothing new has been plugged in.
A bit more questioning reveals that the reason for moving the socket is because it was wired inside one of the old cabinets and that the wires to it went through holes drilled through the cabinet and were bent through 180 degrees where they went through the hole.
I've asked him to unplug everything and retest in case something else has an earth leak and the tester is pushing over the trip swithc limit, but he insists that the only change is the move of the socket.
Any ideas? All I can think of is that if the wires were bent double and he's pulled them out and straightened them then he could have damaged a cable, but why would that cause a problem only when the tester is plugged in?
Unless he's broken the tester somehow?
I'm assuming he hasn't done anything really stupid.....
He's 2 hours drive away and his wife is going spare because they have a 6 month old baby and she's now terrified that the electrics are faulty (and of course it is 5:30 on sunday evening)
He has had to move a socket as part of the refit and he is using a Martindale EZ150 socket tester to check the socket wiring. Apparently before he did anything the tester worked fine and showed all good, low Earth resistance.
After moving the socket the tester does its self test and then the CU trips. Asking him about what they've done he swears that moving the socket and moving an earth bond is the only change.
The kettle apparently works fine plugged in anywhere so they still have tea
He says that the trip switch is 30mA and that nothing new has been plugged in.
A bit more questioning reveals that the reason for moving the socket is because it was wired inside one of the old cabinets and that the wires to it went through holes drilled through the cabinet and were bent through 180 degrees where they went through the hole.
I've asked him to unplug everything and retest in case something else has an earth leak and the tester is pushing over the trip swithc limit, but he insists that the only change is the move of the socket.
Any ideas? All I can think of is that if the wires were bent double and he's pulled them out and straightened them then he could have damaged a cable, but why would that cause a problem only when the tester is plugged in?
Unless he's broken the tester somehow?
I'm assuming he hasn't done anything really stupid.....
He's 2 hours drive away and his wife is going spare because they have a 6 month old baby and she's now terrified that the electrics are faulty (and of course it is 5:30 on sunday evening)
It shouldn't trip the RCD - Although it obviously is.
He says it was giving test results before he touched the socket, so he could have bust it during the afternoon.
As I say all I can think of is that bent cable = damaged insulation = increased leakage and the tester is now pushing things over the RCD limit.
He says it was giving test results before he touched the socket, so he could have bust it during the afternoon.
As I say all I can think of is that bent cable = damaged insulation = increased leakage and the tester is now pushing things over the RCD limit.
Is the 30mA RCD on the main incomer, on each outgoing circuit breaker or is it a split board?
If anything but the first scenario, has he tested on a different circuit?
If the circuit energises, it's unlikely to be a fault with the wiring as the RCD would instantly trip.
What was involved in the socket move?
If anything but the first scenario, has he tested on a different circuit?
If the circuit energises, it's unlikely to be a fault with the wiring as the RCD would instantly trip.
What was involved in the socket move?
I think it is the main incomer, I asked him to try in an upstairs socket and he said that the same happens.
I know that the tester he has isn't ideal - but it is what he has. He doesn't even have a multimeter. All I can go on is what he is telling me.
I don't know what sort of current the tester allows in order to measure the earth resistance - can't be very much?
He tells me that he has unplugged everything else - I'll have to talk to him and make sure that he has undone everything. And as he describes it, the wiring on the moved socket sounds OK - socket seems to be on the ring, not a spur.
If he just turns the electric on, then everything seems normal and OK. everything works until he plugs in the tester. The guy that is helping him is going to take it home with him and check what happens when it gets plugged into his house.
The socket was in a cupboard at one end of the kitchen and has been moved just because the units are being replaced.
The only thing he is telling me that sounds iffy is the cables bent through 180 passing into the old unit.
I've suggested he replaces the cable that was bent in case the insulation has been damaged (and that he gets an electrician in, but I dont think that was viable on a Sunday evening).
He's going to give me a ring tomorrow with an update.
(and the reason he rang me is that 20 years ago my degree got me into the IEE and IEEE - barely used those bits of it though)
I know that the tester he has isn't ideal - but it is what he has. He doesn't even have a multimeter. All I can go on is what he is telling me.
I don't know what sort of current the tester allows in order to measure the earth resistance - can't be very much?
He tells me that he has unplugged everything else - I'll have to talk to him and make sure that he has undone everything. And as he describes it, the wiring on the moved socket sounds OK - socket seems to be on the ring, not a spur.
If he just turns the electric on, then everything seems normal and OK. everything works until he plugs in the tester. The guy that is helping him is going to take it home with him and check what happens when it gets plugged into his house.
The socket was in a cupboard at one end of the kitchen and has been moved just because the units are being replaced.
The only thing he is telling me that sounds iffy is the cables bent through 180 passing into the old unit.
I've suggested he replaces the cable that was bent in case the insulation has been damaged (and that he gets an electrician in, but I dont think that was viable on a Sunday evening).
He's going to give me a ring tomorrow with an update.
(and the reason he rang me is that 20 years ago my degree got me into the IEE and IEEE - barely used those bits of it though)
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