Mains House Electrics

 

Changing one or a number of 13A Socket Outlets.

To carry out these alterations you will need to work through a number of steps:

13A socket outlet ring main circuit
Identify the circuit protection
Isolating and checking the circuit is dead
Removing and securing screws and disconnecting
Replacing a mounting box
Surface Mounted Boxes
Replace a flush mounted box
Connecting the replacement socket outlet
Final assembly
Safety checks before turning on electricity

Tools
Straight Edge, Electric Drill, Screwdrivers, Lump Hammer, Bolster Chisel.

Materials
Green and yellow pvc sleeving, various 13A socket outlets, replacement mounting boxes.

Safety first
Never work on any part of the electrical installation without first switching off the supply at the consumer unit and, where possible, removing the circuit fuse. Always unplug any electrical appliance before doing any work on it. Check all connections are secure and all covers have been replaced before you turn the electricity on again.

13A Socket outlet ring main circuit
The 30A protective capacity of the ring main enables an adequate number of 13A socket outlets to be connected to the circuit. The ring method of connection permits the use of the smaller, more easily installed 20A capacity 2.5mm 2 twin and earth cables. On the ring circuit the conductors need to loop in and out of the various socket outlet terminals and arrive back at the consumer unit to the samme fuse or MCB.

Identify the circuit protection
Carefully remove the front cover from the consumer unit. The design and layout of available consumer units are quite diverse, but in all cases the current rating of each protective device should be clearly shown. The identity of the various circuit ways may be labelled, nevertheless, this information should be confirmed by isolating each circuit in turn.

Isolating and checking that the circuit is dead
Warning, before starting any work to replace a socket outlet. The electrical supply, that relates to the circuit to be worked on, needs to be isolated at the consumer unit and subsequently proved to be dead.

Removing the securing screws and disconnecting
Unscrew the two securing screws on the face of the socket. Carefully ease the face of the socket away from the wall and then disconnect the conductors.

Replacing a mounting box
If it is a surface mounted socket and the mounting box also needs replacing you should do this now. You may have to cut out the plastic windows in the box to pull the wires through on the new box.

Surface mounted boxes Any bare earth wire must be covered with green and yellow sleeving. If it is not, then you must cut the appropriate green and yellow pvc sleeving to length and slip it over the bare conductors. Leave around 20mm of the earth wire still showing.

Replacing a flush mounting box
If you are replacing a single flush socket outlet with a double unit, or if you are converting from surface mounted outlets to flush mounting, you will need to cut out the plaster, brickwork, etc. to fit the new mounting box. Be careful when removing the existing box not to damage the cables. Mark out the position of the new box and cut out a close fitting recess.

Connecting the replacement socket outlet
Bare earth wires must be insulated with a green and yellow pvc sleeving. Loop the circuit earth conductors into the earth terminal of the socket outlet, connect an additional bonding conductor to the earth terminal on the metal mounting box.

Final assembly Make sure all the conducts are secure and connected to the appropriate terminals. Gently push the new fitting into place, taking care to ensure the cables will be not be trapped when the fixing screws are tightened down. On older installations the fixing screws could be imperial, 4BA screw thread, modern installations will have metric fixing screws, 4mm screw thread. Take care to use the correct size of fixing screw.

Safety checks before turning on the electricity
Good workmanship is essential if electrical work is to be safe. Before reconnecting the supply check the work is complete and all covers are securely in place. If you have a continuity tester, check there are no short circuits between live and neutral or between live and earth metalwork. After the electricity is turned back on, plug a suitable appliance into the new socket outlet to check it functions correctly.

 

 

Adding extra 13A socket outlets
or connecting an addition fixed appliance:

A typical 13A socket outlet ring main circuit, with spurs
Information on the types of socket outlets available
Identifying the circuit protection
Isolating and check that the circuit is dead
Adding a spur from a junction box
Taking a spur from an existing socket
Connecting to an existing socket outlet
Information on different types of fused connection units
Connecting an extra fixed appliance
Extending a ring circuit
IMPORTANT! Safety checks before turning on the electricity

Typical 13A socket outlet ring main circuit with spurs
There is nothing absolute regarding the number of ring circuits to be installed in a particular home, there may only be one single ring main circuit installed, or there may be two or even three separate ring circuits. Each socket outlet ring main circuit will consist of a ring circuit, with additional non-fused spurs and fused spur connections.

Types of socket outlets
There are various types of 13A socket outlet, there are single or double sockets and both are available either switched or unswitched. Sockets can either be surface or flush mounted.

Identify the circuit protection
Carefully remove the front cover from the consumer unit. The design and layout of available consumer units are quite diverse, but in all cases the current rating of each protective device should be clearly shown. Usually, the identity of the various circuit ways will be labeled, nevertheless, this information should be confirmed by isolating each circuit in turn.

Isolate and check that the circuit is dead
Warning, before starting any work to add extra socket outlets the electrical supply, that relates to the circuit to be worked on, needs to be isolated at the consumer unit and subsequently proved to be dead. As a precaution, tape over any isolating toggles and post a warning notice to indicate that the circuit must not be made live until it is safe.

Adding a spur from a junction box
Connections are made at a 30A joint box, fixed between the ceiling joists and adjacent to the ring circuit cable. Avoiding cutting the cable, remove a section of the cable sheathing from where it passes over the junction box. Then without cutting through the conductors, expose enough bare wire for connection to the terminals. Cut the earth wire, fit insulating sleeves and connect to the third terminal.

Taking a spur from an existing socket
The spur cable will need to be the same size as that of the existing circuit and will need to be buried in the plaster. You may have to knock out an additional cable entry to take the spur cable.

Connecting to the existing socket outlet
All the cable earth wires need to connect into the socket earth terminal with an additional bonding conductor connecting to the metal box.

ypes of fused connection units Only single type fuse connection units are available. These units afford a means of connecting a fixed appliance to the circuit wiring. Each will have a cartridge fuse, similar to that in the 13A plug and giving protection to the connected appliance.

Connecting an extra fixed appliance
A fused connection unit will have two sets of terminals. Those marked ‘Mains’ are for the spur or ring cables that supply the power, whilst, the terminals marked ‘Load’ are for the flex or cable connecting to the appliance.

Extending a ring circuit
Extending a ring circuit would only be considered when major alterations to the house have been carried out.

Safety checks before turning on the electricity
Before reconnecting the supply check the work is complete and all covers are securely in place. If you have a continuity tester, check there are no short-circuits between live and neutral or between live and earth. After the electricity is turned back on, plug a suitable appliance into the new socket outlet(s) to check it functions correctly.