uksparks
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Hi,
I changed a CU this morning, old 3036 for split board.
I had tested it prior, IR etc, few Zs readings and the like, continuity of rings etc, nothing abnormal, even checked for borrowed neutral on light circuit which there was.
Anyway, changed it this morning, put lights on one rcd and the sockets on another.
Tested everything, R1+R2, IR etc on all circuits and other tests, all absolutely fine, tested every point on each circuit, all readings all ok.
Turn it on after completing all tests...
Everything seems ok, thats good then, walk round the house, switch lights on upstairs so see if they all work as expected, yep, all fine, all fine downstairs, but when it comes to the hall light (not stair light) i turn it on and it trips both RCD's? hmm thats odd. Take the bulb out and its fine.
So i put my meter on it on line neutral and earth, 230 L-N, 230 L-E, 0 N-E, ok so I would imagine the bulb would work.., put it in switch it on again and it trips both.
Anyway, I narrowed it down, it appears there is a link between the socket circuit and that light fitting.
That light fitting is definately on the light circuit.
I even then tested N-E from the socket circuit, so see if theres any reading (dead) at the light, nothing, I tried all combinations, I get zero voltage at the light fitting when the light is off and also when the light MCB is off.
So somewhere, and for some reason that particular light is connected, but cannot seem to do any tests that suggest it is.
Unless I have missed the obvious.
Anyway, so resolve it until monday, I just moved the lights over to the same RCD as the sockets, then on monday will look at it as have got to pull the floor up to add more sockets in anyway.
I was happy to a degree that it was safe to leave for the weekend as I could not get however much I tied any voltage on that light fitting when the lights were off at the CU.
The point to this I guess is, if I had put them both on the same RCD to start with which I may have done, it was just chance I didn't, then I would never have found this problem.
Any thoughts? I can only see that it is connected on the neutral, but can't understand why as when you disconnect the socket circuit at the board, the light still works fine...
Bit of a weird one, I have not had this happen before.
I changed a CU this morning, old 3036 for split board.
I had tested it prior, IR etc, few Zs readings and the like, continuity of rings etc, nothing abnormal, even checked for borrowed neutral on light circuit which there was.
Anyway, changed it this morning, put lights on one rcd and the sockets on another.
Tested everything, R1+R2, IR etc on all circuits and other tests, all absolutely fine, tested every point on each circuit, all readings all ok.
Turn it on after completing all tests...
Everything seems ok, thats good then, walk round the house, switch lights on upstairs so see if they all work as expected, yep, all fine, all fine downstairs, but when it comes to the hall light (not stair light) i turn it on and it trips both RCD's? hmm thats odd. Take the bulb out and its fine.
So i put my meter on it on line neutral and earth, 230 L-N, 230 L-E, 0 N-E, ok so I would imagine the bulb would work.., put it in switch it on again and it trips both.
Anyway, I narrowed it down, it appears there is a link between the socket circuit and that light fitting.
That light fitting is definately on the light circuit.
I even then tested N-E from the socket circuit, so see if theres any reading (dead) at the light, nothing, I tried all combinations, I get zero voltage at the light fitting when the light is off and also when the light MCB is off.
So somewhere, and for some reason that particular light is connected, but cannot seem to do any tests that suggest it is.
Unless I have missed the obvious.
Anyway, so resolve it until monday, I just moved the lights over to the same RCD as the sockets, then on monday will look at it as have got to pull the floor up to add more sockets in anyway.
I was happy to a degree that it was safe to leave for the weekend as I could not get however much I tied any voltage on that light fitting when the lights were off at the CU.
The point to this I guess is, if I had put them both on the same RCD to start with which I may have done, it was just chance I didn't, then I would never have found this problem.
Any thoughts? I can only see that it is connected on the neutral, but can't understand why as when you disconnect the socket circuit at the board, the light still works fine...
Bit of a weird one, I have not had this happen before.