Lighting puzzle

OK it's Friday night and I really have got better things to do other than to sort out a friends lighting problem! This is the situation. New place, just moved in, toilet light not working, so change bulb ....nothing. Check bulb, thats OK. Check power with non-contact power tester, indicates power BUT all the time regardless of switch position. Checked tester on other appliances etc and all ok there. So, power + good bulb = no light! I suspect a switch problem of some sort, any ideas or suggestions?! Will try a new pull switch in the morning, but would be interested to hear your thoughts :-)
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johno wrote on 23/01/2009 :

If the live is there (a volt stick would tend to confirm it), then the neutral is missing. Another possibility is poor connections around the lamp-holder.
A volt stick in the hands of a practised user can be used to check for the lack of a neutral - When testing a two core flex, it will light up when moved around the entire circumference if the neutral is missing. If both live and neutral are there it will only light up on part of the circumference. you can restrict the sensing range/angle of a stick by screening the tip between your finger tips.
--
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Harry (M1BYT) (L)
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On Fri, 23 Jan 2009 21:17:49 +0000, Harry Bloomfield wrote:

Could it just be that both wires are live? You don't actually need current flowing to light up a volt stick, IIRC.
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After serious thinking PCPaul wrote :

That was the point I was making - a missing neutral would make both L and N live.
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Harry (M1BYT) (L)
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wrote:

Could also be of course that the neutral is being switched and the switch is faulty - ie permanent live. Horrible to think of but knowing the clowns that are around!!
Rob
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Checked that, it is live switching! Nasty thought though.
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wrote:

Will give that a try in the morning, cheers
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Your 'power tester' may indicate many different things!
As has been discussed, there may be L at the light fitting, but no good N.
Also, there may be a poor contact causing high resistance between the supply and the light fitting. Under no-load conditions, 240v will be present at the fitting. With the lamp installed creating load conditions, theis voltage may drop right down.
There's no substitute for a good meter, and the knowledge to interpret the readings.
--
Ron




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johno wrote:

dump the voltstick in the bin and get a multimeter. Then you can test from each contact in the bulbholder to earth, and you'll actually know whats going on.
NT
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snipped-for-privacy@care2.com wrote on 24/01/2009 :

Keep the voltstick, learn to use it - but do supplement it with multimeter.
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Harry (M1BYT) (L)
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