Adding a socket outlet - spur from a junction box in a ring main

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Plan and instal the new socket outlet

Power may be supplied via a junction box inserted in the ring main, provided the limitations of the regulations are not exceeded.

Make sure the power is switched off at the consumer unit and the fuse removed from the circuit.

Determine the nearest point at which the ring main passes the location of the new socket. Fit the new socket and run the cable to this point.

Installing the junction box

Mount a 30 amp junction box screwed to a suitable surface. You may need to fit a wooden batten to support it on.

Depending on the type of junction box, you may need to tap out three of the blanked side access points. Other types allow the cover to be rotated to provide the required number of access points.

With the cover of the box removed, lay the ring main cable alongside and mark the amount by which the sheath will need to be trimmed back.

Slit the outer sheath without cutting into the insulation of the individual conductors and peel back and remove it where marked.

Cut the earth wire in the centre and fit green/yellow sleeving to both ends so as to leave 1/2" of conductor exposed. Do not cut the live and neutral, but trim the insulation back to expose 1/2" of the conductor in the middle.

Strip and prepare the end of the cable of the new spur ready for connection.

Connecting the cable at the junction box

Remove the terminal screws. Fit the exposed section of the live (red) conductor in one of the outer terminals and fit the live (red) conductor of the new spur with it. Replace the terminal screw and tighten.

Repeat the process for the neutral (black) conductors using the other outer terminal.

Place the three earth (green/yellow) conductors in the middle terminal and secure with the terminal screw.

Double check that the connections are correct – only conductors of matching colour share terminals – and that the insulation of each conductor butts right up to the terminal.

Replace the junction box cover, rotating if necessary to suit the entry points and fasten its retaining screw.

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 another socket
• Extending a ring main to supply a new socket
• Mounting socket boxes