Lighting circuit breaker issue

[Dave84]

Hi,

Looking for a little help please as there is a problem on the lighting circuit. It doesn't seem to be related to any particular light or switch as the circuit breaker will trip even with all the lights switched off, and the breaker itself sparks when you try to untrip it and hence won't untrip. This leads me to believe its the breaker itself. It is a standard wylex push button type, 5A. Can I just pull this out and replace it with another? Maplin or Screwfix don't seem to stock the type I have

Does anyone know where I can get one or can it be replaced with a switch type without doing any wiring? Pull one out, slot one in sort of thing?

Thanks

 

[jj4091]

What's wrong with the e-bay ones you have been looking at?

 

[Dave84]

SWMBO wants it fixing today

 

[ericmark]

The MCB's are available they now look like this

but if it sparks then there must be a load so unlikely the MCB at fault some thing has gone faulty could be anything from rodent damage to cupboard screw through wire but with no load there should be no spark so something is taking current.

 

[Dave84]

You're quite right, it seems the house alarm takes power from the lighting circuit, one more thing to check....

 

[Dave84]

I took the fuse out of the alarm, and the lights still tripped so it does look like its the breaker. Do I just turn the mains off and pull it out to remove it?

 

[flyingsparks]

Sounds like a fault with the installation rather than the mcb. You may need an electrician to try and find it.

 

[ericmark]

I would not expect an alarm panel to draw enough current to cause a spark when resetting a MCB. If nothing drawing current there will be no spark so I would agree with "flyingsparks".

Lighting circuits as well as lights often have bathroom extractors and shaver sockets on the same circuit.

As to changing MCB yes main switch off but I can't remember if the base for old type is same as base for new type or if base needs changing too. Only one screw if it does but does expose live parts.

Question is always what work has been done in the house? It is not that uncommon for a screw to end up through a cable and since no earth leakage fitted it could result in non electrical items becoming live.

So in interest of safety I suggest calling an electrician rather than DIY with this problem.

 

[Dave84]

Thanks for the advice, I still think I'd like to replace the MCB first just on the off-chance as it'd be a lot cheaper than calling an electrician out. Do I just pull it out?

 

[Dave84]

Recently no work has been done, it just started happening yesterday. The suspect MCB also wiggles and none of the others do. If I can get a like for like replacement I'll just bob it in, and if the problem persists I'll call a spark

 

[riveralt]

Thanks for the advice, I still think I'd like to replace the MCB first just on the off-chance as it'd be a lot cheaper than calling an electrician out. Do I just pull it out?

Yes after turning the power off.
I take it you have checked the integrity (visual and/or yank test) of the live cable going to the mcb and its equivalent at the neutral bar?
Had a similar job recently with equally old but rocker switch MCB, which according to the customer, 'sparked when he tried to turn the MCB on.
Turned out to be the neutral wire that had gone south.

 

[Dave84]

Yes it seems fine, it looks in very good condition. I think this is going to be one of them things, because everything is fine now and I can't get it to trip. I've had a good look at all the wiring that I can and looked at the wiring in all the light switches and it all seems fine.

Thanks for the help everyone

 

[Dave84]

For future readers or those that may be interested, the new style MCB fits straight in to the old style base.