Light switch trips breaker but not always

DB_SamX

DB_SamX

DB_SamX

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Joined
17 Feb 2006
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Winchester
New flat built 5 years ago, bought and moved in December. Said light switch has 3 switches - lounge, kitchen, and kitchen counter.

Since start of this year, every now and again (maybe once a week), turning the lounge switch on trips the breaker (lights only), and blows one of the bulbs. Has happened 3 times so far.

First time was when I turned both lounge and kitchen simultaneously.
Second and third times I think kitchen lights were already on (I think). (Also can't quite remember if it's deffo the lounge switch only that causes the problem, also rarely use the counter lights so no idea if they're part of the problem.)

Any thoughts where problem might lie or what causes it? If it persists I will get an electrician in, but the fact it is so intermittent has me confused. Is it bad not to get it fixed, and just keep on resetting the breaker if it keeps tripping?
 
You really need to nail it down as to what exactly is causing the issue. This'll make things so much easier for you and your electrician to diagnose.
 
Yeah, that's what I want too. I've already started turning things on in a certain order to try and replicate the fault but no idea when it will trip.
 
Are you sure you're not attributing the result to the cause?

I.e. are you sure its not the bulb blowing when the light is turned on, causing the breaker to trip. It could be that the bulbs are the same age and just reaching their EOL?
 
What type of light fitting is it?

Hard to say without taking a look....but it could be a worn out switch or loose wire in the switch either causing arcing sometimes and tripping the mcb - does the light always come on and does it flicker at all?
 
Amp34 said:
Are you sure you're not attributing the result to the cause?

I.e. are you sure its not the bulb blowing when the light is turned on, causing the breaker to trip. It could be that the bulbs are the same age and just reaching their EOL?
Click to expand...

Good point. I changed all the 3 blown ones yesterday so will see.

BigBoy said:
Have you checked all earthing and are any of the light fittings metal or been changed recently?
Click to expand...

Not that I am aware of. As said, flat was only built 5 years ago and there are no signs of electrical works since. How would I check earthings?

HardwareGeek said:
What type of light fitting is it?

Hard to say without taking a look....but it could be a worn out switch or loose wire in the switch either causing arcing sometimes and tripping the mcb - does the light always come on and does it flicker at all?
Click to expand...

No, never flickered, always came on. The lights are ceiling spotlights. GU10 50W ones I think.
 
Fault finding an intermittant fault is an art. I'd suggest you get a sparky in to do a test on the circuit. He'd probably start with an insulation resistance test to see if the insulation is breaking down somewhere (perhaps water getting in to the circuit or a nail or screw catching). It's really not something you can do without proper test equipment and a working knowledge of the circuit.
 
Amp34 said:
Are you sure you're not attributing the result to the cause?

I.e. are you sure its not the bulb blowing when the light is turned on, causing the breaker to trip. It could be that the bulbs are the same age and just reaching their EOL?
Click to expand...

Just to close the thread, you were right. It was the bulbs blowing that cause the breaker to trip!
 
DB_SamX said:
Just to close the thread, you were right. It was the bulbs blowing that cause the breaker to trip!
Click to expand...

Classic with cheap GU10 bulbs they fail to short circuit so trip the breakers used to drive me mad when we had a rented flat and the landlord had put rubbish spots everywhere including the bathroom where the bulbs were a pig to change!
 
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