MCB trip

[keith]

About a month ago i ran a spur to feed a socket in my garage,after connecting and checking i switched on mains supply.The mcb that supplies the ring the i was using sparked and tripped out,after checking all connections that i had made i tried again.This time everthing seemed ok with no trip.The trouble i am having now is that the same mcb trips out about once a week for no reason.This has happened twice in the middle of the night with no switches used.An earlier request for help for a similar problem suggested a fridge/freezer coming on to be the cause,the mcb i am having trouble with is not on the same circuit as any of the kitchen appliances so this could not be the cause. I will be gratefull for any theories about my problem .Thanks for any replies KEITH

[nick smith]

Swap it with another same value MCB on the board and see if the problem moves or not - that will say whether the problem is in the MCB or on the circuit it is supplying

Nick

[Christian McArdle]

Did checking include measuring the continuity (with a specialised tester that provides 200mA of current), insulation resistance (with a specialised tester that provides 500V DC) and earth loop impedence (with a specialised tester that pulls 20A down the line)?

If not, obtain said testers (or an electrician) and see what the results are.

Christian.