mcb tripping

[CK123]

Hi
Hope someone can help!
32A MCB trips at least once a day, has been doing it for about a week.
The circuit is the downstairs ring. can't pin it down to anything, no recent work has been done and it doesn't follow any pattern. Everything has been unplugged at some point. It will also trip through the night so i'm thinking its not likely to be overloading!
If it's a short on the wiring wouldn't that tend to trip out more frequently?
Does a cartridge fuse disconnect slower than an MCB?

Any help would be appreciated....cheers

 

[garagerob]

it might be worth just changing the MCB, is it very old?? they can and do fail.
As for the cartridge/fuse blow time that depends on a few things i think.
Do you mean a typical thirteen amp plug top type?

 

[RF Lighting]

it might be worth just changing the MCB, is it very old?? they can and do fail.

Not really. I maybe come across one failed MCB every three years or so, and they either work or they don't. They don't develop intermittent faults.

Back to the OP.

It sounds like you have a fault on your fixed wiring.

This could be anything from vermin damage to a cable which has been trapped in a floorboard and has finally worn through.

Faults can be apparrent all the time, or they may only appear once a month. It depends entirely what is causing the fault, how well it is making contact between the wires and a few other variables. It can even be down to something like metals expanding and contracting with heat, water ingress etc. The list is endless.

Intermittent faults can be difficult to trace, but a decent electrician armed with an insulation tester should be able to track it down.

Don't even bother swapping the MCB with a cartridge fuse. This will not make any difference. The MCB is doing it's job, which is to disconnect the power when a fault is detected to prevent the destruction of the wiring which could lead to fire.

 

[CK123]

Hi

Thanks for the replies, looks like it's time to go under the floor . As regards the disconnection thing, just wondered if it was an appliance or like, whether the fuse in the plug top would blow before the MCB tripped out?

Cheers

 

[Taylortwocities]

Before we head off down Red Herring Drive can we just check for sure that what you have is an MCB and not an RCBO?
They look quite similar but the RCBO has a test button on it.

Pop in a picture or state what is written on the breaker if u not sure.

 

[RF Lighting]

Oh right. Sorry I think I misinterpreted what you meant there with regard to the cartridge fuse.

Normally there should be sufficient discrimination between a 32A type B MCB and a 13A plugtop fuse to take out the 13A fuse if the appliance were at fault, but, occasionally a large current can cause an MCB to operate quickest.

Oh and do what the post above says too. He talks alot of sense that lad.

 

[CK123]

Hi

Defo an MCB 32A Btype 6ka BS60898.

Cheers