Pop!

[zaarin_2003]

I have LED downlights all round the house. I just turned on my study lights, and pop! There was a brief flash, which to my mind looked like it was localised to one of the four spotlights in the study, and the lights on the whole floor went out. The RCD for the whole floor had tripped. I put it back on and the lights to the floor were restored, except of course in the study. All four are still off, the light switch does nothing.

I've tried taking out each of the four lights one by one, in case having a faulty light is preventing the rest turning on, but it makes no difference.

Any ideas? Could the light switch have gone? What could cause all four lights to cease working, but the rest of lighting on the floor on the same circuit is not affected?

Thanks

Matt

 

[Steven Prentice]

Tripping the circuit often happens - older lights were bad for that (the loose wire in the light flopped about, touched the other and without the resistance in between cause a short circuit and pop). Did you take all the lights out all at once or was it one out at a time? It is possible that the switch is faulty however if the flash was at the light fitting then that is unlikely. Are the lights all in one unit or are they separate lights all controlled from 1 switch?

 

[JohnD]

The RCD for the whole floor had tripped.

I bet it wasn't an RCD.

what sort of light switch have you got in the room?

What voltage are the bulbs?

 

[zaarin_2003]

I bet it wasn't an RCD.

what sort of light switch have you got in the room?

What voltage are the bulbs?

What do you mean you bet it wasn't an RCD? Whatever you call it, the box with the row of fuses - the one operating the 1st floor lighting had tripped into the off position and flicking it back to on restored power to the 1st floor lighting, except the study.

The light switch is a dimmer. Press it in to turn the four lights on/off, rotate to dim/brighten. Neither action does anything now, after the flash of light.

The bulbs say 220-240v and 5w.

 

[zaarin_2003]

Tripping the circuit often happens - older lights were bad for that (the loose wire in the light flopped about, touched the other and without the resistance in between cause a short circuit and pop). Did you take all the lights out all at once or was it one out at a time? It is possible that the switch is faulty however if the flash was at the light fitting then that is unlikely. Are the lights all in one unit or are they separate lights all controlled from 1 switch?

The lights are four separate spot lights in the ceiling, like the four spots on the 4 of a six sided dice. They're all separate, but they are controlled by just the one switch. I took them out one at a time, testing the light switch, then replacing the light and moving on to the next one.

I saw a flash and it appeared to come from the ceiling rather than the switch, but I can't be 100% sure - it was like a flash of lightning, if you know what I mean. Bright, white but very brief.

 

[JohnD]

The light switch is a dimmer.

Fit a standard switch and see if it then works.

 

[Murdochcat]

my money is one one of the LED lamps failing and taking the dimmer with it

 

[JohnD]

Too slow!

 

[zaarin_2003]

Fit a standard switch and see if it then works.

Ok, I'll get a switch and test it. I'm curious as to why though? It's been a dimmer since we moved in in 2013 and there's never been an issue like this before. I can't remember the last time I had to change the lights, they're long lasting and designed to be dimmed. I dim them all the time.

 

[zaarin_2003]

my money is one one of the LED lamps failing and taking the dimmer with it

That can happen? A bulb can go and nuke the dimmer along with it?

 

[JohnD]

Yes.

If not that it might be a connection, quite likely in a ceiling rose.

Try the switch first.

 

[ericmark]

The old tungsten light bulb could fail with ionisation of the gases in the bulb causing a very high current for a short time, there should be a fuse in each bulb, but in real terms the fuse is often missing. But the high current is well known for taking out dimmer switches.

With the new LED we should not have this problem, but the old CFL I know could fail short circuit and weld the bulb into the holder, clearly the fuse was not fitted in the one I had which did that, it tripped the B16 MCB which taught me a lesson, now use only 6 amp, but so much current it welded bulb into holder, so had to replace whole outside light, and stopped buying bulbs from Ikea.

Likely new switch will cure problem, and use of LED lamps likely to stop a repeat, but we can only guess.

 

[zaarin_2003]

The old tungsten light bulb could fail with ionisation of the gases in the bulb causing a very high current for a short time, there should be a fuse in each bulb, but in real terms the fuse is often missing. But the high current is well known for taking out dimmer switches.

With the new LED we should not have this problem, but the old CFL I know could fail short circuit and weld the bulb into the holder, clearly the fuse was not fitted in the one I had which did that, it tripped the B16 MCB which taught me a lesson, now use only 6 amp, but so much current it welded bulb into holder, so had to replace whole outside light, and stopped buying bulbs from Ikea.

Likely new switch will cure problem, and use of LED lamps likely to stop a repeat, but we can only guess.

You were right! I bought a new dimmer and replaced it for the old one - presto, problem solved. One bulb remained dead, which must have been the culprit. Thanks!

 

[Murdochcat]

That can happen? A bulb can go and nuke the dimmer along with it?

Oh yes AND LEDs can , on failing sometimes introduce a dead short into the circuit