Summary: Wiring a new electric socket: Learn how to wire a socket, extending a circuit, wire the connections at the supply socket and wire the connections at the new socket.
* Notifiable project requiring Building Control approval. Installation must conform to Electrical Regulations.
A simple way of installing a new electric socket is to a run a spur from an existing socket on a ring main circuit. The socket you choose to run the spur from must, however, be selected carefully. Do not use a socket that is already supplying a spur or is supplied by another spur. Furthermore, the combined floor area of the rooms supplied by the circuit after the new spur has been added must not exceed 100m2
The supply socket
- Switch off the power at the consumer unit and switch off the MCB – or remove the fuse – that protects the circuit you intend to work on. A simple way of checking that the circuit is no longer live is to plug in an appliance and switch it on. For example a lamp or radio.
- Unscrew the faceplate from your chosen socket and pull it away from mounting box to reveal the cable cores connected to terminals on the back of the faceplate.
- If there is only one cable the socket is already supplied by a spur. Three cables indicate it is supplying a spur. In both cases the socket is not suitable and must not be used.
- A socket with two cables running from it should be suitable. To check that it is on a ring main use a continuity tester following the instructions in Using a continuity tester.
- Having located a suitable socket, unscrew the terminals and release the cores from the faceplate. Then undo the screws that fix the mounting box to the wall and remove it.
Extending the circuit
- Prepare the cable route to the location of the new socket following the instructions in Preparing the circuit route.
- Feed the new cable from the supply socket to the new socket.
- Thread the ends of the cable through the holes in the mounting boxes at the supply and the new socket after fitting grommets in the holes to protect the cable.
- Screw both mounting boxes in position.
Making the connections at the supply socket
- Prepare both ends of the new cable following the instructions in Preparing cable and flex for connection.
- At the supply socket you will now have three cables. The cores from all three cables should be matched – Live (L), Neutral (N) and Earth (E), and connected to the corresponding terminals on the faceplate. It is important to remember that if the circuit was installed before 2006 the colour-coded insulation on the Live and Neutral cores of the existing cables will be different to that of the new cable.
Old colour coded system for cable cores
Red – Live
Black – Neutral
New colour coded system for cable cores
Brown – Live
Blue – Neutral
The earth cores on both the existing cables and the new cable should be covered with yellow-and-green sleeving. If the earth cores of the existing cables are bare then they should be covered with yellow-and-green insulation. For more information see Cable.
- Red and brown cores should be connected to the terminal marked L.
Black and blue cores should be connected to the terminal marked N.
All yellow-and-green cores should be connected to the terminal marked E.
Ensure all the cores are held securely in the terminals.
- With the connections made, push the cores into the mounting box and screw the faceplate back in position.
Making the connections at the new socket
- At the new socket connect the cores to their corresponding terminals on the faceplate.
Connect the brown core to the to the terminal marked L.
Connect the blue core to the terminal marked N
Connect the yellow-and-green core to the terminal marked E.
- With the connections made push the cores into the mounting box and screw the faceplate to the mounting box.
- Returning to the consumer unit, replace the fuse or switch the MCB back on, and turn on the mains supply.
- Insulated screwdriver
- Continuity tester
- Wire cutters/strippers
- Trimming knife
- New socket
- Yellow-and-green sheathing
The colour-coding system for electric cable changed in 2006, make sure you read Electric cable and flex to view the new information.