Pop and burn

[mikeey84]

Hi, I turned some lights on earlier this week, there was a pop, burning smell and both the MCB for that circuit and the RCD switched.

Upon turning the RCD and MCB back on, the lights worked. No blown bulbs, no visual signs of damage.

Now, one of the ceiling roses on that circuit had been removed, and wago connecters used in its place to keep the circuit so other lights could be used.

At the time, I had quite a bit of plastering done, so the air was very damp.

I've not had a chance yet to take any lights apart yet to see if there is any damage.

My supposition is that condensation (it was first thing in the morning when this happened, and there was a lot of condensation on the windows) could have caused the issue (a short circuit?) Somewhere is an accessory.

Beyond looking for burnt wires/connections, is there anything else I can do? All lights working well.

 

[terryplumb]

When was plastering done ?
Is one fitting still not in place ,and wiring still in wago' s ?

 

[mikeey84]

Plastering was done the day before this occurred, so was still very wet.

Yes, rose hasn't been put back yet as we haven't got round to painting yet

 

[terryplumb]

Worth turning mains power off and checking the connections / wiring at ceiling. Any other ceilings plastered ,or just the one ?

 

[mikeey84]

Yeah, that's the plan. Just wanted to understand what, if anything, I should also do.

Just the one ceiling plastered, but the smell/noise didn't seem to be coming from the missing ceiling rose, but its not easy to judge that!

 

[terryplumb]

Any walls plastered ,light switches affected ?

 

[mikeey84]

Nope, just the ceiling, although it was overboarded, and I don't know where the cable runs, so a screw through the circuit is not completely unrealistic

 

[terryplumb]

Ah that's a possibility ,but It would likely have tripped a breaker when the screw went thru a cable ( if indeed that happened).

 

[mikeey84]

Ah that's a possibility ,but It would likely have tripped a breaker when the screw went thru a cable ( if indeed that happened).

That was my thinking, although if it was a near miss, I thought drawing a load may have caused it to go. But that's an uneducated guess!

 

[Jackrae]

Not if the cable was the switched feed to the light and the screw pierced the SL and Earth.

That being the case then the RCD should have tripped due to a N-E fault, the neutral being routed (connected) to the switched-live via the bulb filament.

 

[mikeey84]

It did when the lights were turned on, not when the plasterboard was screwed up

 

[mikeey84]

There are 6 lights from 1 switch, 1 was connected with wagos as I'd taken the rose off for the plastering, all the other lights had bulbs in. The cable was most likely screwed through between the light that wasn't there, and the 5 other lights that were operational.

 

[mikeey84]

Sounds like a plan.

 

[securespark]

I have visited jobs where a screw has been put through a twin cable (no cpc) and initially it was fine but over the course of a weekend, the screw has eaten through the conductors' insulation and ''turned'' the light on.