Lighting MCB keeps tripping

[STPMotors]

Hi all.

Just after a bit of advice.

Just got home on Christmas Eve, went to put the lights on as you do, then there was a "pop" from the MCB.

Usually when this happens one of the halogen bulbs in the bathroom has gone and needs replacing. Usually resetting the MCB, identifying the blown bulb and replacing does this trick.

This time, the MCB trips straight away. Won't reset at all.

We've been through the house, checked all lights are off. Still won't reset.

We did find an old filament bulb that had gone, so we've taken that out and replaced it, but still the MCB won't reset.

Anyone have any ideas we could try?

The rest of the MCB is fine, we have power to sockets, cooker, etc. Just the lighting affected.

Trying to call local electricians at this time on Christmas Eve isn't going too well.

 

[rapparee]

One of the transformers on the halogen lights has probably failed

 

[Rpa07]

Or the mcb has been damaged by the short/spike.

 

[STPMotors]

Thanks for the repliess so far, I don't know if it makes any difference, but a little bit more info...

The bathroom has 4x individual GU10 halogen bulb downlighters across the ceiling.
The kitchen has 3x GU10 bulbs in a single ceiling unit.

The rest of the house has energy saving bulbs.

All light switches are set to off, but MCB trips straight away with a "pop".

if it is the MCB damaged, which seems logical, I'll wait until an electrician wakes up on Boxing Day.

Thanks for your quick replies.

 

[Dave OCD]

I'd also have a look at your outside lights and see if there's any sign of water ingress.

 

[Bob Geldoff1234]

When you try to put the MCB up,does it trip down with a pop? or is it just not staying up ie.floppy?

 

[STPMotors]

Trips with a pop,

 

[snowhead]

Which light did you switch on just before the MCB tripped?

 

[STPMotors]

That'd be the bathroom - where the 4x GU10's are.

 

[Pete999]

Hi all.

Just after a bit of advice.

Just got home on Christmas Eve, went to put the lights on as you do, then there was a "pop" from the MCB.

Usually when this happens one of the halogen bulbs in the bathroom has gone and needs replacing. Usually resetting the MCB, identifying the blown bulb and replacing does this trick.

This time, the MCB trips straight away. Won't reset at all.

We've been through the house, checked all lights are off. Still won't reset.

We did find an old filament bulb that had gone, so we've taken that out and replaced it, but still the MCB won't reset.

Anyone have any ideas we could try?

The rest of the MCB is fine, we have power to sockets, cooker, etc. Just the lighting affected.

Trying to call local electricians at this time on Christmas Eve isn't going too well.

Switch all the lighting switches to the off position, reset the MCB and gradually switch the lights back on until the MCB trips, if it does there is your problem circuit.

 

[Dave OCD]

When you try to put the MCB up,does it trip down with a pop? or is it just not staying up ie.floppy?

Ooh matron.

 

[Dave OCD]

That'd be the bathroom - where the 4x GU10's are.

Are they operated by a pull switch, did you turn it off again when the MCB tripped off ?

 

[snowhead]

Take ALL 4 GU10s out of the bathroom lights.

 

[Strima]

As the MCB is tripping it means you have a short circuit somewhere.

You mention GU10 fittings, I would probably start looking at those fittings for signs of overheating, not the first time a GU10 has been covered in insulation and has melted the wiring PVC.

 

[STPMotors]

Replying to a few questions in one here...

All lights switches are in the off position. When reset the MCB trips with a pop straight away.

I've just replaced all 4x GU10s in the bathroom with new ones and the same thing happens. (They are operated by a rocker switch outside of the bathroom).

We don't have any outside lights.

I've taken out and left out thr 4x GU10s in the bathroom. Reset the MCB - it doesn't trip this time, but there are no lights in any of the rooms still.

 

[Wilko]

I've taken out and left out thr 4x GU10s in the bathroom. Reset the MCB - it doesn't trip this time, but there are no lights in any of the rooms still.

If I've understood correctly you now have the light mcb staying on? But no lights in the bathroom. What happens if you turn on any light switches (even the bathroom light switch) ?

 

[STPMotors]

If I've understood correctly you now have the light mcb staying on? But no lights in the bathroom. What happens if you turn on any light switches (even the bathroom light switch) ?

Absolutely nothing. mCB is in on position, but no lights in any room

Just noticed there is a tiny little red/green indicator on the MCB.

With all of the others in the ON position the indicator is red.

Now the lighting MCB is in on position, the indicator is green/white
.

 

[snowhead]

Photo of MCB ?

 

[STPMotors]

Apologies if it isn't very clear, just point and hoping for the best ...

 

[suffolkspark]

Mcb is ducked now id say if green tab is showing its still off regardless of toggle position. Was gonna sugest checking bathroom fan isolator is off but may be a bit late...

 

[snowhead]

Apparently MK B6 mcb are known for failing, see link.
It may latch if you switch it off and on a couple of times, but do that with the RCD under your finger in the OFF position.

If it does latch to Red and works it's still going to need changing later. At least there's a spare next to it for whoever you get in to change it.

IET Forums - Faulty MK MCB's - https://www.------.org/forums/forum/messageview.cfm?catid=205&threadid=29419

 

[littlespark]

2 minute job for a spark to utilise the spare 6A.... but it may be there is still a fault with the circuit that wrecked the first one

 

[STPMotors]

Thanks for all your help guys, really appreciate it.

Very frustrating, but comforting knowing there's nothing I can do to let their be light tonight.

Got hold of a local guy who's popping round Boxing Day.

 

[littlespark]

We hardly use our lighting circuit at this time of year.
Tree lights, candles, little lights on silver sprayed twigs in a vase....

‘It’s the season... La la la”

 

[static zap]

Do all the switches feel normal ?
(contacts may have welded ) ...
Bathroom is main suspect.
( though 2 way hall/landing switches can take a bit of predicting !)

 

[dmxtothemax]

Is it just a standard over current type circuit breaker ?
Or Is it an RCD type breaker ?

 

[telectrix]

We hardly use our lighting circuit at this time of year.
Tree lights, candles, little lights on silver sprayed twigs in a vase....

‘It’s the season... La la la”

that reminds me. got to pay the gas bill. can't be without lights over xmas.

 

[Toneyz]

So what was the cause?

 

[STPMotors]

Just seen your reply.

The circuit breaker was knackered.

Sparky tokd us the root cause traced to some dodgy DIY (before we moved in, I'll add).

The previous owners put shelves up in a cupboard and managed to drill through some cables. Their fix was to pop some tape over it.

All sorted now, it was quite cosy without lights (I'd dangled some Christmas tree lights across the living room ceiling to give a little light).

 

[Toneyz]

Thanks for coming back to the forum and letting us know the outcome many don't.