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Live Earth Reverse

Discussion in 'Electrics UK' started by CSun, 17 Mar 2017.

  1. CSun

    CSun

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    Last week I renewed the metal back box on a twin socket. Everything was working fine before & after fitting. Whilst I was in there I noticed nine wires - three of each. Two of the earth wires were connected to the metal back box with only one in the socket & this is how I put them back.

    Just to make sure I purchased a cheap circuit tester and got the two green lights. I have today put up some plasterboard and so had to the front socket off again. I have reconnected everything as before but now when I put the circuit tester in and put the mains back on (without putting the switch to the on position) I get a red light on the circuit tester - Live Earth Reverse.

    I have tried a new double front socket & checked and rechecked the wires but cannot see anything? So I've removed the socket and tapped up the ends of the wires for now.

    Any ideas/help/advice appreciated.
     
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  3. JohnD

    JohnD

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    photos please

    of the cables in the backbox, and also of the wires in the socket terminals
     
  4. CSun

    CSun

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    No photos right now - two earth wires are connected to the backbox & the other one is in the earth terminal in the socket. I have double & treble checked the wires and they are/were in the correct terminals on the socket. At the minute I have disconnected the socket and tapped up the end of the wires.
    I thought I may have trapped a wire & it was some how "earthing out"?
    As I say it was working fine before this afternoon before I put pasterboard & had to disconnet the socket again.
     
  5. Taylortwocities

    Taylortwocities

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    Hard to advise, unless we can see the wiring...
     
  6. endecotp

    endecotp

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    Was there also a short length of earth wire between the socket's earth and the back box earth?


    What does it show when the switch is on?
    I don't think the indication with the switch off is very useful.

    This will have broken the ring, which is not a good idea; it could lead to overheating of wires elsewhere.
     
  7. CSun

    CSun

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    Now I am worried. I thought it best to disconnect to avoid any problems?

    I just saw the red light & didn't do anything else as I thought switching it on my cause even more problems? All the other sockets in the kitchen are working ok. In fact this one socket appears to feed two other sockets. I tested both of them & got the red light warning LER on one of them however, when checking the other socket it gave the green lights and still does so now. As I have disconnected the socket with the nine wires the socket that was showing the fault is not live & so gives no reading however, as I said earlier the other fed socket is showing green lights?

    As for the earth wires. There are in total nine wires coming into the back box. It was last week I fitted the new back box & as per the old one I connected two earth wires that were connected to the back of the old back box & one to the front plate/socket., I didn't notice any short wires & everything was working fine & when tested got the green lights on the tester.

    Everything was ok today until I reconnected after fitting the plasterboard. I have checked all the wiring as best I can & can't see anything trapped or catching anywhere?
     
  8. EFLImpudence

    EFLImpudence

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    All the earth wires should be connected together - and to the socket.
     
  9. endecotp

    endecotp

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    All three earth wires must be connected together and to the earth terminal on the socket.
    They should also be connected to the earth terminal on the back box.
    The screws that connect the socket to the back box will connect the earths together, but you should not rely on that; there should be a wire between the terminals.
     
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  11. Jackrae

    Jackrae

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    If the unit is powered from the mains (no internal batteries) and you get any lights with the switch off then you have problems elsewhere.

    Have you tried the unit in a separate socket with both switch on and off to see if you get similar results

    What is the make and model number of your 'tester'
     
  12. CSun

    CSun

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    The tester is just a cheap basic one from screwfix, LAP tester, powered by the mains
    I have tried all other sockets - no reading then when you put the tester into the switch, then when you put the switch to on - two green lights, working fine.

    I am a little lost on the earth wire advice.
    Am I correct in assuming you mean take the two wires that are in the metal back box terminal and put them into the front panel (switch) together with the one that's already there? How then do I also connect them back to the metal back box.

    What's even more confusing for a numpty like me is that for over a week in the configuration I stated in my opening post everything worked and tested correctly.

    Thanks for the help so far.
     
  13. EFLImpudence

    EFLImpudence

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    Yes.

    With another piece of wire - although this isn't mandatory, it is a good idea.
     
  14. Jackrae

    Jackrae

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    All 'incoming cable 'earths' connect to the faceplate and one extra length connects from there to the backbox terminal.
    If the socket switch is OFF then NO lights should be lit on that type of tester.
    If you do not have all three earth wires connected together then one of them might be 'floating' and picking up an induced voltage which makes the tester 'think' it's a 'live' wire.
     
  15. omega015

    omega015

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    You have two options now, 1. call out an electrician to troubleshoot and put right or 2. start troubleshooting.

    For the troubleshooting, you say you have 3 sets of wires going to that socket assuming this is 2 for the ring and 1 is a spur. Separate each set of wires and put a single set of wires into the socket and then test with that (taping off all the other conductors so they don't short with each other or anything else).
    See what reading you get with the first set, if all is good then disconnect tape off and then test with the next set of wires. If one of those set of wires produces no results on the tester then this is likely a spur and make a note of this one.

    By 'set of wires' I mean 1 live, 1 neutral, 1 earth all from the same cable. Also send some pics as you go about this test so we can get an idea of what your seeing/doing. If this is all too much for you to do safely and confidently then I suggest option 1.
     
  16. CSun

    CSun

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    Assuming I've understood correctly, first I'll try (fingers crossed that my torch batteries last) the earth wires.
    I'll put all 3 incoming earths into the face plate terminal (socket) then run one wire (earth) back from the same earth terminal (effectively 4 wires - earths in that terminal now?) back to the metal back box.

    If that doesn't work I'll try the troubleshooting you have suggested & some pictures.

    Thanks again for the help - much appreciated. What really gets me is that I all the replacement & checks to see if everything was working before putting up the plaster board & it works fine. Then today - a fault occurs.
     
  17. endecotp

    endecotp

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    It would be really useful to see some pictures.
     
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