Bulbs Keep Blowing

[pdq1]

Whats the likely cause for 40W halogen bulbs in the bathroom blowing. There are 2 separate bulb sockets but the fault lies only in one of them. We put 3 different new bulbs in but they all blew not straight away but within days. You could almost tell they were about to blow as they flickered occasionally. The RCD didn't trip.

[yogi-bear]

Sounds like a loose connection in the wiring, pdq....... would call out an electrician to check it out, if you cant inspect it yourself....should'nt cost a lot especially if you call out one with free callout charges waived....better to be safe :)

[Buenchico]

It's possibly a loose connection somewhere, causing arcing with subsequent current surges. Turn the power and remove the socket to see if you identify any loose connections. If you can't, try replacing the socket. (They're cheap!).

A relevant thread:
http://www.electriciansforums.co.uk/electrical-forum-general-electrical-forum/37161-light-bulbs-keep-blowing-why.html

[woofgang]

Are the new bulbs all out of the same packet? We had a duff packet a while ago and went through them like nobody's business. We got a lecky to check the light fitting but it was fine. he suggested the duff bulb pack so we bought another pack of a different make and its been fine since.

[pdq1]

No the bulbs are from different packets bought from different stores. Also if its a wiring problem wouldn't the RCD trip off?

[Buenchico]

>>>Also if its a wiring problem wouldn't the RCD trip off?

Physics was a subsidiary subject for my degree but I gave up trying to apply scientific logic to domestic wiring circuits a long time ago! Circuits sometimes trip out, or fuse, at current loadings well below the nominal rating. Equally, I've known circuits to be grossly overloaded without anything tripping out or blowing. The best example I've got is when I was working on stage and disco lighting for a school. Because we were limited to using standard 13A circuits, we had to take care to share the loading across lots of different sockets. However one day a 'helpful' pupil plugged everything in when I wasn't around. I found that we'd been pulling 62A through a single 13A socket (on a circuit that was both fused and RCD protected) for several hours without anything blowing! The only sign of anything wrong was that you could burn your hand if you touched the wall where the cables ran!

I still think that simply replacing the socket (for a few pounds from Wilkinson's) is likely to solve your problem.

[Teddio]

It may be the transformer. Your bathroom lights will likely be 12 Volts. There is often a separate transformer (240 V to 12 V ) for each bulb. They can be bought for less than £4 from Amazon.

[buildersmate]

Chris (and OP)
RCDs do NOT trip on current overload, that is what Miniature Circuit Breakers (MCBs) do. MCBs are the switch blocks found in a line bank on the CU and have various ratings such as '16A', '32A' assigned on their casings.

RCDs trip when there is a recognised earth leakage fault at very small currents. They ar physically much bigger - about 50mm square on the front panel and they have a test switch mounted on them. You get one or two per CU.

It is unclear what the OP is talking about here - he says 'RCD' when he could mean 'MCB'. Either way both types of protection device can trip as the result in intermittency in the circuit they are protecting.

[Tweed]

If it's the bulbs that stop working after a short time then it could be excessive heat, maybe from loft insulation above the lights.

[Tweed]

i.e. build up of heat if it can't escape due to insulation on top of lights.