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
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.