Adding a socket outlet - spur from another socket on a ring main

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Plan for the new socket outlet

Power may be supplied from another socket outlet on the ring provided it does not already have a spur from it and it is not a spur itself. Check with the I.E.E regulations to ensure compliance.

Switch off the power at the consumer unit and remove the fuse for the circuit and inspect the wiring at the socket.

You must make quite sure that this circuit is indeed a ring main. If you are not absolutely certain, consult a professional electrician.

If it has one cable, it is itself likely to be a spur and cannot therefore be used.

If it has two cables it may be a suitable socket on the ring, assuming that somebody has not incorrectly connected two spurs at the same socket.

If it has three cables, it is already feeding a spur and may not be used.

Adding the new cable

Once you have found a suitable socket, fit the new one and run cable back to this point.

Make sure the power is still off and remove the face plate of the socket to which you are going to connect.

Slacken the terminal screws and remove the pairs of conductors from each terminal.

If there is sufficient space alongside the other cables, feed the new cable through the side entry of the box.

If not, remove one of the other blanking plates in the box to provide entry for the new cable. Fit a rubber grommet to the new entry hole and feed the cable in so that there is sufficient to allow for connection.

Strip and prepare the end of the new cable ready for connection. Protect the exposed earth conductor with green/yellow sleeving.

Connecting the spur cable at the original outlet

Taking the conductors of the new cable, one at a time, twist each together with the corresponding pair from the original cables. Now insert the groups of three conductors into the correspondingly labelled terminal.

Three red conductors to the terminal marked live (‘L’).

Three black conductors to the terminal marked neutral (‘N’).

Three green and yellow conductors to the terminal marked earth (earth symbol).

Tighten the screw of each terminal ensuring that the conductors are firmly held and that the insulated part of each butts right up to the terminal.

Re fixing the socket outlet

Double check your connections and ease the face plate back to the box folding the cables carefully as you do so.

Re fix the retaining screws, tightening them alternately to ensure that the plate is drawn back evenly.

Once you are sure that all work has been completed correctly, replace the fuse for the circuit, switch the power back on, and test.

• Supply new socket from a junction box
• Extending a ring main to supply a new socket
• Mounting socket boxes