Fuse keeps tripping on Light Circuit (Wylex B6)

[miint]

Hello All

I have an issue where the trip switch trips at random times - even if the lights are off!. We have had a leeking flat roof and didn't do much about it as it was un-noticed until we went in the garage. we left it and then it soon went into the kitchen. It took a few months to get the roof repaired, however now the roof is done, my attention has gone to the electrics.

I've changed the B6 to no avail - All the contacts on the light fittings look ok, therefore does anyone else have any suggestions?

Its a very random problem. The switch instantly or after 10 minutes. I've tried turning on each light one by one to see if it trips however thats proven inconclusive.

Help!

 

[holmslaw]

..

 

[miint]

Unfortunately, intermittant electrical faults can be very difficult to rectify.
An insulation resistance test might pinpoint the problem area.

Any ideas how to carry out?

 

[JohnD]

ask around friends a neighbours for their recommendations of a good local electrician.

Ask him if he is a member of a self-certification scheme, which one, and how long he has been a member.

Or you could spend several hundred pounds on test equipment and try to trace it yourself.

It never hurts to look inside ceiling roses for signs of anything wrong.

If you have an outside lamp on that circuit it has probably got rainwater in it.

 

[miint]

ask around friends a neighbours for their recommendations of a good local electrician.

Ask him if he is a member of a self-certification scheme, which one, and how long he has been a member.

Or you could spend several hundred pounds on test equipment and try to trace it yourself.

It never hurts to look inside ceiling roses for signs of anything wrong.

If you have an outside lamp on that circuit it has probably got rainwater in it.

Lol.. I'll try removing the fittings as see if anything has corroded... Failing that it will be an electrician....

 

[riveralt]

Unfortunately, intermittant electrical faults can be very difficult to rectify.
An insulation resistance test might pinpoint the problem area.

Any ideas how to carry out?

You will need an insulation resistance tester capable of generating 500v dc and a proving unit. Test that the IR tester is working with the proving unit.

Since you know which circuit is faulty then turn the power of to the whole installation and make sure the circuit you are working on is dead.
At the Consumer unit remove the line, neutral and cpc from the MCB, neutral bar and cpc bar respectively for the circuit under test.
Ensure that all lamps are removed from the circuit and that the switches are in the on position.
Ensure that all dimmer switches are removed from the circuit and either linked out or replaced by normal switches. Remove and link out any other electric motor device such as a extractor fan - since their presence on the circuit will causing anomilies in the figures.
Ensure that all terminations at the switches and ceiling roses are secure.
Then using the conductors at the CU test between line and neutral, line and cpc and neutral and cpc. Depending on your test meter you should have a very high Mega ohm reading.
A low reading on any of the tests will suggest you have a problem with the wiring somewhere on the circuit.
If this is the case, then you will have to conduct the same test but break down the circuit between the CU and the first lamp on the circuit then test - again you are looking for a high Mega Ohm reading. Keep doing this until you find the length of cable or part of the circuit that is causing the problem. (You can also divide the installation into two and test each side to see which is causing the problem - then sub-divide again until you find the issue)
Alternatively call an electrician out.