Electric fire tripping electrics - could it be damp? Updated...

RainbowLaura

The other night I switched on my electric fireplace and there was a very loud bang from inside it, and it tripped the electrics. I flipped the switch back on in the fuse box (marked B32) and everything came back on and was working fine, including said fireplace. This also happened around a year ago, but that time the bulb inside the fire also shattered.

The first time, we thought the bulb blowing had caused the problem, especially as it was fine for a year afterwards. However I have had a horrible thought... the fire is plugged into an external wall, where the DPC is stepped because we are on a hill. Basically the outside DPC is above ground and not bridged, but it's about 4 courses higher than the internal one (and the living room floor). I don't think it's ideal but was built that way due to the hill (house about 20 years old).

Could this be a potential damp issue? And would an electrician be able to tell us? I'm hoping there's something up with the fire, which I'm happy to just get rid of. We have had some extremely wet weather recently, so wouldn't we have seen further problems on wet days if it was damp related? I am now scared to use the electrics downstairs at all

Mistral001

The electrical wiring will be fixed to the inner skin of the wall which I assume is not damp. It will not be anywhere near the outer skin where the moisture will be.

RainbowLaura

Thanks Mistral - I'd like to assume the inner leaf isn't damp too but I worry that somehow it might be... I've always been convinced that it wasn't built properly and worry about water filling the cavity or something. Hopefully we'd have noticed before it started affecting electrics though!

Jonesya

There's two issues here.

For the damp, household wiring is normally PVC (plastic) cable which assuming it is undamaged shouldn't be affected, but any accessories like socket or junction boxes could be if water or moisture collects inside, as it can cause short circuits if it gets bad enough.

For the bang, kind of stating the obvious but if electrical equipment makes a loud bang and trips a fuse or circuit breaker then that is due to a fault of some sort, and before you start using it again you should get it checked over to find the cause and repair it, before putting it back into use with a potential fault.

coffeehound

Difficult to diagnose remotely but another possibility is dust build up. If dust was bridging between a live conductor and earth or neutral, then on switch-on it could provide a momentary current path to trip the breaker. But it would have instantly gone up in smoke, so the fire was okay when subsequently switched on again. Just guessing.

As far as wet in the wall socket goes, that would trip the breaker whether or not the fire was switched on, so shouldn't be the cause. It must be inside the fire.

Owain_Moneysaver

Damp would be more likely to trip the RCD which is very sensitive.

A B32 MCB is going to take a lot of current to trip it. (A bulb blowing can sometimes do it.) The fire is faulty. Maybe something's fallen inside (coin? tinsel strand?) or a wire has become loose and caused a short.

missile

I would replace the fire. What price safety?

RainbowLaura

Thanks everyone, this is reassuring
The fire hasn't been used since the other night when the bang happened, and won't be again. We only kept using it after the first time last year because we assumed it was the bulb that caused the bang, so nothing dangerous. My main worry this time was that the wall might be damp inside, as we can't keep the electrics off all the time and it would be very expensive, if not impossible to fix. But it sounds more likely that the fire itself is faulty. Either way, it's weird that everything worked fine for a year in between! We will get an electrician to come and check, though as it's only happened twice im not sure he'll be able to detect anything.

RainbowLaura

Another question - Owain you mentioned the RCD. I tested that and it is working, so is it strange that the MCB tripped without affecting the RCD? I'm not sure if there are any clues there, or what the difference is other than RCD being a safety feature that trips when there's a fault. I also don't get why the fuse hasn't blown in the fire? So grateful for your thoughts; the electrician hasn't got back to us yet and it's making me really anxious.

Owain_Moneysaver

RCD detects minor leakage to earth, typical of damp.

MCB detects major short circuits, typical of a fault. MCBs can trip faster than a plug fuse will blow. A bang from the fire indicates a fairly serious short circuit. I've had "less serious" short circuits and they only made fizzing noises and white flashes before the MCB tripped.

RainbowLaura

Owain_Moneysaver wrote: »

RCD detects minor leakage to earth, typical of damp.

MCB detects major short circuits, typical of a fault. MCBs can trip faster than a plug fuse will blow. A bang from the fire indicates a fairly serious short circuit. I've had "less serious" short circuits and they only made fizzing noises and white flashes before the MCB tripped.

Thank you so much - this makes me feel a lot better. There was also a white flash from the fire actually. Under no circumstances will it be used again!!