i'm in the uk, and I've taken the wall lights off and the earth wire and the neutral are both black, how do I tell which is which. thank you john

  • 2
    Can you post a photo of this situation? – ThreePhaseEel Nov 1 '18 at 11:31
  • If you're able to figure this out, label the wires for next time. – mrog Nov 1 '18 at 20:15

Make a test lamp ( a simple bulb connected to two wires). Connect one wire of the test lamp to the live wire and then using the other wire touch the black wires one by one. The bulb will turn on normally and brightly when joined to the neutral wire. It will be dim when you touch the ground wire. Or there are chances that the bulb will not turn on in case the ground has been disconnected in your house.

  • 2
    If the circuit is protected by RCD, when the light is connected between line and ground the RCD will trip. – DDS Nov 1 '18 at 17:56
  • Don't bypass it. If the RCD trips, then you know the wire you are testing is the earth ground. – longneck Nov 1 '18 at 20:01

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