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Discuss Discovered a bare live wire in the Electrical Wiring, Theories and Regulations area at ElectrciansForums.co.uk.

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  1. Guesty
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    Guesty New EF Member

    Location:
    Uk
    Hi all, new member. I'm a decent DIYer but no electrician!

    We moved in to our home just less than a year ago. This evening I have replaced the thermostat on the boiler with a nest.

    While I was installing the heatlink in the cupboard under the stairs I noticed 2 parallel old cables. They were painted over, which was different to the other cables in the cupboard. It was located towards the top corner of the cupboard near the light and pull cable switch. To my alarm it was cut off, with bare wire exposed.

    I grabbed my electric testing screwdriver. Worse still. IT WAS LIVE!

    I flicked the switch on the consumer unit for downstairs lights (a guess because it was next to the current light) and tested again. This time my screwdriver had a dim red light compared to before. How can this be? Surely if it is on that circuit it shouldn't be live in any sense?

    I know you will probably tell me I need a sparky to tell me exactly what the cable is doing. And I'm aware of this. But to put my mind at rest, why would the cable still be live, but the tester says not so live?! Should I be terminating the cables some how?

    Thanks for your help in advance. I just can't believe someone would leave electrics in this way!
     
  2. Richard Burns
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    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    It is possible that the cable has been disconnected but a parallel cable may be causing a slight voltage to register on the screwdriver as they are not very reliable testers.
    Obviously professional testing would be the best solution, but as a start it may be safe to visually trace where the wire goes, perhaps into the loft and see if it is connected into a junction box somewhere. If it is connected then if you turn off the main switch on the consumer unit it should be safe to disconnect the cable, but it is best to test the exposed cores of the cable with a contact voltage tester before working on them.
     
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  3. ferg
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    ferg Electrician's Arms

    Location:
    N.W.Scotland
    Your Electric testing screwdriver belongs in the bin.

    The cable should be terminated but I wouldn't recommend using the screwdriver for safe isolation.

    It's nearly impossible to say what is going on without seeing it.

    If you post up your location perhaps one of the members will be near to you.
     
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  4. ferg
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    ferg Electrician's Arms

    Location:
    N.W.Scotland
    Richard beat me to it with a much better worded and more polite reply. :)
     
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    • Funny Funny x 1
  5. Guesty
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    Guesty New EF Member

    Location:
    Uk
    Thanks both... Especially Richard. Haha

    I do worry what else I'll find in this house. Can a multimeter be used as a contact voltage tester? Thanks for the advise regarding the screwdriver!
     
  6. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    You may well be reading phantom or ghost voltage !
    Cheap voltage detectors or volt sticks can give erroneous readings !
    Even digital style volt meters can give erroneous reading too
    to be sure you need a low impedance analogue style volt meter.
    they impose more of a load on the line, so if it's not real, it will disappear.



    phantom voltage (or ghost voltage). The term is often used by electricians, and might be seen, for example, when measuring the voltage at a lighting fixture after removing the bulb. It's not unusual to measure phantom voltages of 180v volts when testing the wiring of ordinary 240 V circuits with a high-impedance instrument. While the voltage produced may read almost to the full supply voltage, the capacitance or mutual inductance between the wires of building wiring systems is typically quite low and incapable of supplying significant amounts of current.
     
  7. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    agree with all the previous posts. for peace of mind get an electrician to check it for you. as ferg. said, post you location and one of us may be close enough to call.
     
  8. mickfred
    Online

    mickfred Regular EF Member

    Location:
    Liverpool
    Hate test screwdriver .Why do good brands of vde set give you one in the pack is beyond me. Side note just invested in a fluke t150 and really liking the earth shutter pin
     
  9. Guesty
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    Guesty New EF Member

    Location:
    Uk
    Thank you all for your guidance big help. I followed the cable back, and it is cut off the other end too... Blooming screwdriver tester....so i shall remove the cable and the screwdriver from my belongings haha.

    While I have you, what do you make of this mess in the photo? Surely a lot is not used and it is possible to get it all in 1 consumer unit? And remove a lot of it... There's even something in there that's ticking... I think that might be an old storage heater timer?

    20170911_222934.jpg
     
  10. telectrix
    Online

    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    agree. a tidy up into a nice shiny amd. 3 CU (12 way should do) would be my advice. a dual RCD DB, or an all RCBO jobby, depending on your budget. loads of qualified sparks on here would be happy to quote you, if we knew where you were.
     
  11. Guesty
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    Guesty New EF Member

    Location:
    Uk
    Awesome. I'm in Kingswinford, West Midlands
     
  12. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
  13. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    QUOTE - [ i shall remove the cable and the screwdriver from my belongings haha. ]
    non contact testers are good enough for a simple "DIY" yes/no test.
    But should not be relied upon with reguards to human safety.
     
    • Agree Agree x 1

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