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Topic Title: Light fault ???
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Created On: 04 January 2013 06:27 PM
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 04 January 2013 06:27 PM
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goldenboy1818

Posts: 472
Joined: 22 February 2011

Hi came across a lighting fault today and didn't have time to go into it deeply will be going back Monday. I wondered what you all thought or if you had come across anything similar. I used my kewtech tester to test a light after I had changed a faulty switch. It was showing 197 volts on my meter and would get a zs reading. I dropped the light down and found 238 on L - N, 180 on L - E, and 50 on N-E. This was also the case at other lights on this circuit. The other lighting circuit was fine and normal though, so were the sockets. Thanks for any input
 04 January 2013 06:34 PM
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DOUGIE1000

Posts: 4161
Joined: 13 August 2005

I would expect the kewtech showing 197 and your 180 l-e is the same reading as just variation between equipment out out of calerbration etc.

However the fault seems pretty common enough,

Dougie

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Dougie
Power Plus Electrical.co.uk

My mission is to live as long as possible......so far so good!
 04 January 2013 06:34 PM
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Rulland

Posts: 458
Joined: 11 April 2008

Earth

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Those who make no mistakes do very little work!!......
 04 January 2013 06:51 PM
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goldenboy1818

Posts: 472
Joined: 22 February 2011

Earth, as In no earth ? How does that explain the voltages ?
 04 January 2013 07:02 PM
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DOUGIE1000

Posts: 4161
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Yup 100% sure your earth is shot, keep testing closers supply to on same cpd and won't take too long o find

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Dougie
Power Plus Electrical.co.uk

My mission is to live as long as possible......so far so good!
 04 January 2013 07:19 PM
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goldenboy1818

Posts: 472
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So you reckon a earth is out somewhere ? Why the voltages as they are ?
 04 January 2013 07:59 PM
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JZN

Posts: 556
Joined: 16 November 2006

Do a cpc continuity test with a wander lead when you go back and it will have come adrift somewhere.

You need something to measure the voltage against, so you got OK voltage between live and neutral because the neautral was effectively providing a good zero to measure the live against.

If the earth was good you would have got the same reading. As you are using a high input impedance tester you will still measure something even if the earth is disconnected or poorly connected. V=IR so the 180ish volts you measured is the product of a tiny current but very high input impedance of the meter. If you had used an old analog meter I think it would have registered zero volts.

John
 04 January 2013 08:21 PM
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SKElectrical

Posts: 910
Joined: 01 February 2009

I am on such a fault tmrw. il let you know the outcome.
 04 January 2013 08:26 PM
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aligarjon

Posts: 2811
Joined: 09 September 2005

i had one of these before Christmas. ive never seen so many junction boxes and chocolate boxes under a floor. i gave up after a couple of hours and rewired the ground floor lights in the end. fortunately no carpets with lots of floors already up by the plumbers. (they do have their uses. )

definately in my top 5 of worst diy installations i have seen


Gary

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 04 January 2013 09:09 PM
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goldenboy1818

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I did get the same reading with my multimeter too
 04 January 2013 09:29 PM
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Rulland

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As Gary, and I dare say many others, weird measured voltages like that are down to bad cpc continuity.

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Those who make no mistakes do very little work!!......
 06 January 2013 04:41 PM
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goldenboy1818

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How did you get on sk ?
 07 January 2013 12:27 AM
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SKElectrical

Posts: 910
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I got her parents to babysit and we drove to Bournemouth for the weekend instead. Strange place.
Will let you know in the week.
 07 January 2013 05:49 PM
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goldenboy1818

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Got mine done today, as you all said no earth continuity. A earth was loose in a light fitting, thanks all
 07 January 2013 07:00 PM
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Rulland

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Cheers for reporting back mate, glad you got it sorted.

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Those who make no mistakes do very little work!!......
 09 January 2013 10:21 PM
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SKElectrical

Posts: 910
Joined: 01 February 2009

yeah, same outcome here - was a cpc that had come out of connector block.
What's worse is that it was the only damned fitting on that floor that I had installed: un-##**ing-believable!!
(I took down nearly every other fitting and pulled up treated floor boards.
 09 January 2013 10:56 PM
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impvan

Posts: 752
Joined: 07 September 2005

Get rid of that new fangled digital meter thingy and get an old AVO. You will then find you don't get spurious readings from floating earths.
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