Weird Problem! Light circuit fuse trips when lights are off!
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Weird Problem! Light circuit fuse trips when lights are off!

Post by edeb » Wed Jul 22, 2009 11:40 pm

Yes, you read that right!

There is only one lighting circuit in my small flat, it has never complained before, all my lights are energy saving so not much power goes through it.

The lighting fuse began tripping at intervals of 2 - 20 minutes. It would never trip instantly when i flipped it back on, even with all lights switched on.

In trying to isolate the faulty light, I accidentally discovered that it would trip even when every single light was turned off. I replaced the MCB fuse and still have the same problem.

I have checked every single light fitting twice and I am satisfied that they are dry, wired correctly and ship shape.

Using lamps from the sockets is no great hardship so I thought I'd ask around for something obvious to check before I call an electrician.

Many thanks in advance,


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Post by sparx » Fri Jul 24, 2009 8:34 pm

Hi, as you have replaced the MCB, presumably 6A rated, and it is this that trips and not an RCD you do have a serious problem since a 6A type B mcb will carry more than 6A for hours before tripping.
With all lights off there has to be a virtual short circuit some where.
have you had any work done which could have caused cable damage?
eg, hung a picture with a nail through switch wire, screwed down a squeeky floor board, how long ago did this start to happen, gotta be a bit of a detective in this game!
regards Sparx

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