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Tracing a break in the neutral

Discussion in 'Electrics UK' started by opps, 28 Sep 2018.

  1. opps

    opps

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    Hi all.

    Just finished working for a client and went to refit the kitchen under unit lights.

    Previously I had simply unplugged the 12v lights from the connector blocks. On reconnecting them none of the lights on the right hand side of the kitchen work. The ones on the left hand side of the room still work though.

    Having looked at the junction boxes that the transformers run into I get 222V across the neutral and switched live and 222V between the switched live and earth, nothing between the neutral and earth. Am I correct in believing that those would be the results even if there was a break in the neutral given that the transformers are still connected?

    I have a sneaking suspicion that there is a break in the primary neutral where the twin and earths exit the wall above the units.

    Strangely one of the transformers is slightly warm and shows a volt or two, the others are showing zero volts.

    Short of running a neutral from one of the ceiling lights is their an easy way to test the neutral? Would simply disconnecting the transformers result in the readings between the live and neutral dropping down to zero volts in an event of their being a break in the neutral?

    Thanks in advance.
     
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  3. EFLImpudence

    EFLImpudence

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    That would be results from a sound circuit.

    Not sure what that means.
    If both transformers are connected to wires with those results then there cannot be a break in the supply neutral.

    Not if it supplies both transformers.

    Have you measured the output from the transformers. Perhaps one has died.

    If it results in voltage between it and live then there is nothing to test.

    No, of course not.

    I am still unsure what exactly you mean.

    If there is 222V between L and N then there cannot be a break - removing the transformers will make no difference.
     
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  4. flameport

    flameport

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    Far more likely that one of the connectors / plugs / sockets has a loose wire, or if it's those horrid mini 2 pin plastic efforts that one of the pins in the plug has been pushed back out of place.
     
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  5. opps

    opps

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    Thanks for the reply, much appreciated. There are a total of 4 transformers on the right hand side of the room. None of which now seem to work.

    I had thought that the transformers being in the "loop" might have given me false readings with regard to the neutral vs live readings.

    For clarity (and profound apologies for not mentioning it earlier) there are a total of 4 transformers.

    2 are over wall unit number 1, which has two T&E. Unit 2 has one transformer and 2 T&E. Unit 3 has one transformer and one T&E.

    The other side of the room has one transformer, which wasn't touched and still works. The dimmer switch has two switched live wires (I assume one is for the left hand side of the room and the other is for the right hand side).

    Is it really likely that all of 4 the transformers on one side of the room failed at the same time? do they get grumpy if there is no load for a month?

    Sorry to be a PITA but I can't think of any logical reason why all 4 transformers would fail.
     
  6. opps

    opps

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    They are those types but all four transformers?

    I have tested the bulbs, only one doesn't show continuity.
     
  7. EFLImpudence

    EFLImpudence

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    It is not likely four transformers would fail at once, so - it must be something wrong before the first one.

    Do you have 222V between the supply contacts at the first transformer?
     
  8. ban-all-sheds

    ban-all-sheds

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    Grow some reality - what do you think?


    That might well mean that they haven't.
     
  9. ban-all-sheds

    ban-all-sheds

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    Not saying this to be combative, but you really should not be providing electrical services to your clients - you should leave those aspects to an electrician.
     
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  11. opps

    opps

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    Valid point.

    All I was doing was disconnecting/unplugging those cheese wedge shaped 12v halogen light fittings so that I could paint around them.
     
  12. opps

    opps

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    I haven't determined which is the first transformer yet. Will check later, thanks.
     
  13. opps

    opps

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    I eventually worked out which cable was the feed.

    What do you know, all 4 transformers were indeed dead. Have replaced them.

    TBH, although the client says they were working, I honestly can't recall if I had turned the lights on before removing them.

    Thanks for your assistance.
     
  14. ban-all-sheds

    ban-all-sheds

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    Ah - there have at times been stories here of the most outrageous "well it was working fine before you <whatever>" porkies that homeowners have tried on.
     
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  15. ban-all-sheds

    ban-all-sheds

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    You've forgotten British Gas Homecare :mrgreen:
     
  16. securespark

    securespark

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    I have had many a customer tell me with multiple light fittings "They all went off together, I'm positive!"

    They are absolutely convinced of this.

    What they meant was, they popped off one by one, but they only noticed a distinct lack of light when the last one gave up the ghost.
     
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  17. opps

    opps

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    I haven't used BGHC so I can't really comment.

    Fasthosts ripped me off.

    Fonesafe told me that they would not honour my lost phone claim because I failed to get a crime number from the Latvian police when I lost my phone on my last day in Riga. 5 months later I noticed that they were still charging me. I assumed that it was simply an oversight... Nope, because I didn't specifically say "Oh, by the way, please cancel the policy on the phone that I no longer have", Fonesafe decided that they are allowed to charge me for a service that they cannot provide. They then insisted that I pay another month as part of the 30 day cancellation process.
     
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