Check a wall socket’s wiring

When replacing an old wall socket you have to check the wiring already there before simply connecting up, because modifications may have to be made to bring the wiring up to date.

The main thing to remember when doing this is that you should never use a cable with only two wires to connect a new fitting. This will be an indication that the cable is a very old one and it should be replaced by a qualified electrician. The wiring regulations currently in force will determine whether you can upgrade the socket, and again an electrician can advise on this.

On your own account, you can perform a few basic checks when deciding whether it is safe to convert a socket.
The first step is to plug a small lamp into the socket and switch it on. Then go to the consumer unit and isolate the power; if the lamp goes off you will know that you are on the right circuit.

Take the socket out of its mounting box and check how many cables are inside it. The socket can be safely converted if you count three separate cables.

If there are only two cables inside the socket, these will be earth and twin types and be distinguishable by their red/brown and black/blue colour markings respectively. Disconnect them from their respective terminals using a screwdriver and separate them out. Unplug all the other appliances on that circuit and use a continuity tester to check the wires. Do this by touching the probe to the red/brown wires and if continuity is indicated then you will know that the socket can be converted, because it is on the ring circuit.

If there is just the one cable present, trace it right back to its origin. If you find that it joins with a box or socket on the circuit then it may be safely converted.

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