Sorry - DIY'er question - halogen bulb keeps blowing

[rusty]

Sorry - I'm not trade, I don't have anything long term to contribute to this forum and professionals like you guys probably have limited time for people like me who try to go it alone and then mess up - but I'm hoping one of you will indulge me with a one off question.

My father and I recently did my home bathroom. On the basis that the existing wiring on the old light supply was recent large cable and solid, we branched the existing light supply into two with a junction box. One branch runs a normal B&Q halogen light fitting, the other one runs an identical light fitting and in series a standard bathroom extractor fan. The wiring was all then sealed in with an insulated tongue and groove false ceiling that as you might understand I'm not keen to take apart and re-jig if I can help it. All was done with proper mains cable, and the light fittings use 60 watt capsule type halogen bulbs.

On the branch that (as I remember it) also runs the extractor fan, the bulb blows every couple of weeks. This always trips the RCD. Does the effect of having an electric motor (and the current fluctuations that probably causes) running on the same wire cause halogen bulbs to blow? Is it likely that the way it is done is fundamentally dangerous/wrong and do I need to take the roof apart and add a third branch for the fan, or do I need to just replace the existing light fittings with one that uses a different type of bulb that is less susceptible to having a motor running on the same wire?

Again, sorry for posting a question like this in a professional forum, hopefully one of you kind souls will take the time to humor a beginner, even if just to ------- me for not using a professional in the first place. Thanks in anticipation!

 

[Adam W]

It can do, for the reason you stated. Heat is another factor to take into consideration - if the bulb hasn't got enough space to dissipate the heat that can shorten it's life.
Junction boxes should be avoided wherever possible, so you don't have to take ceilings down and suchlike, but in either case they should be accessible as per regulations.
The other possibility is that B&Q have sold you a duff fitting.

When you say you wired the fan 'in series' do you actually mean you wired it 'in parallel' ie like connections together?

Moisture is another factor - the fittings in a bathroom need to be suitably IP rated appropriate to the zone of the bathroom they're fitted in.

If you specify which town you're in there may be someone here who could have a look for you - it shouldn't cost you an arm and a leg!

 

[rusty]

I'll speak to my father tomorrow (he did the wiring) but thinking about it I think the term "in series" is incorrect - I think we branched a live / neutral from one existing wire that originally served one light fitting into three sections of mains cable using a junction box - one for each light fitting and one for the fan. Technically it's "accessible" but that would involve the removal of about 50 screws to take the false ceiling down - I should have made a hatch, if the ceiling has to come down I will include one as part of putting it back up. Obviously I'd need to take it all down and expose the wiring before I could get a proper sparky around to look at it.

I had no idea junction boxes were a bad thing. I'll read up on why.

The fittings are both screwed directly to the tongue and groove ceiling, were of a type approved for "bathroom" use and aren't recessed at all - so there's plenty of air around them and I don't think heat is a problem, having gone and felt them now there doesn't appear to be any heat there. As a first thing to check I like the idea that one of the fittings might be duff - I'll swap them around tomorrow and see if the one that blows repeatedly does the same on the other wire.

Thanks mate, I really appreciate the time you spent reading and answering my question, I'll update this thread on the outcome of swapping the light fittings.

 

[Deleted member 9648]

Are you sure it is the RCD tripping..?...more likely the MCB,which often trip when a lamp blows,as there is a current surge,a lamp failing should not affect an RCD.
It could be simply rubbish lamps,and coincidence that the same one keeps going.
We all get a lot of queries over 'lamps keep blowing,must be a wiring fault'...it's nearly always cheap rubbish lamps thats the cause.

 

[sparc]

So just to confirm, you're talking about a 240v G9 lamp like this - http://www.diy.com/diy/jsp/bq/nav.jsp?action=detail&fh_secondid=9279710&fh_location=//catalog01/en_GB/categories<{9372013}/categories<{9372029}/categories<{9372111}/specificationsProductType=halogen_bulbs/specificationsSpecificProductType=standard_halogen ?

Assuming you are using correct max rating and lamp type for the fitting it's difficult to see why wiring would cause lamps to blow, and wirepuller's answer about dodgy lamps seems most likely.

 

[pblec]

i'd safely say they're in parallele as if they was in series you'd be saying my lights aren't very bright i've got 50W 'bulbs' in them and i'm sure they're not even 1/2 as bright as they should be.

for me like the other 2 posts its down to cheap DIY store lamps.

also naughty naughty, you've added extra fittings in a special location which means you should have notified the local council for planning permision. it might seem a pain but these rules and regulations are to protect you, and potential future occupants - even though the advice is freely given the correct process should have been followed.

welcome to the forum as well.