How To Install A Plug Socket Outlet


There are a number of different types of plug socket outlet so make sure that you choose the right one before you attempt to install a plug socket. Flush-mounted outlets are the most common and obviously the neatest. They consist of a steel backing box recessed and fixed into the wall and a faceplate which screws on to the front.

I have put in some videos which cover US and UK wiring. There is not actually a lot of difference so you might as well watch both to learn a bit more about wiring sockets.

how to install a plug socket outlet

Surface-mounted outlets are installed where it is difficult or impractical to cut a hole in an existing wall. They have a square backing box which is fixed directly to the wall and a faceplate — identical to the flush mounted plate — which is screwed on to the front. Most surface mounted sockets are made of white plastic but you can also buy strong, impact resistant metal boxes and faceplates for a garage or workshop.

Even if you fit a surface mounted outlet you still have to hide the cable. The obvious way is to cut a channel for it through the wall. But you can avoid the bother that this entails by using plastic conduit or mini-trunking. Here the cable is led through a neat surface-mounted plastic channel which runs along the top of the skirting board or up the side of an architrave. Many conduit systems come complete with their own surface mounted socket outlets as well as angled adapters which allow you to turn corners and right angles. Note, though, that existing flush outlets have to be converted to the surface mounted type if power is taken directly from them.

Whatever type of socket you decide to fit remember that it is always possible to install a double rather than a single outlet — although you will need to cut out a larger recess to fit a flush mounted socket.

Fused connection units

If you want to install an extra outlet in a bathroom — for a wall heater or towel rail, for instance — it would be dangerous (and in Britain against the electrical regulations) to use a plug and socket. Instead you must install a fused connection unit — a fitting which links the appliance directly and permanently to the power supply.

The unit is fitted and wired in a similar way to a socket outlet and can be either flush or surface mounted. A number of different face plates are available — so examine the range carefully before you buy. For instance, some are switched and some have a pilot light which tells you when the unit is on or off.

Where the power comes from

If you want to add a new socket outlet, the power does not have to come all the way from the consumer unit or fuse board — it can be drawn from any suitable existing outlet as long as you do not overload the circuit.

Start by determining whether you have a ring or a radial circuit.

If you do not know already, switch off at the mains. Unscrew the faceplates of three sockets around the house. Pull each faceplate away from the wall and examine the wires carefully. Sockets wired on a ring main have two sets of cable, each consisting of a red live wire, a black neutral wire and a green/yellow earth. Those on a radial main have just one set of wires. You may be unlucky enough to choose a socket which is an ‘extra socket’ itself or is the power source for somewhere else.

So continue opening up sockets until you have established a definite pattern.

Once you have found out whether you have a radial or ring circuit wire up according to the following rules:

  • On a radial circuit system draw power only from a socket with one set of wires (that is, the last socket in that particular circuit).
  • On a ring circuit system draw power only from a socket with two sets of wires (that is, a socket not previously added to in this way).

Siting the new socket

The next step is to decide exactly where you want to put your new socket. As a general rule, try to position it at a minimum of 150mm above the level of the floor or worktop and well out of reach of anyone working at a sink.

For flush mounted sockets and installations where the cable is to be hidden in the wall, you must take into account the type of wall construction. On a solid masonry wall you can fit the socket almost anywhere; but on a timber framed (stud) wall a new cross member or trimmer needs to be added between two studs to take the backing box. The cable is then fed behind the skirting to the socket.

If you are not certain what type of wall you are working on, test it by tapping the surface with the handle of a screwdriver — a hollow sound will indicate that it is a stud or timber frame construction, a dull thud that it is solid (probably plaster on brick or building block).

If you discover that you are dealing with a frame wall, ‘sound out’ the whole area you want to work on. By trial and error you should be able to work out roughly where the timber uprights (studs) and crossbearers are sited (bearing in mind that they are probably at rough 400mm or 450mm centres) and mark their positions in chalk across the face of the wall. Once you have a good idea of where you want to install your new outlet, plan the best route to take the cable from there to the socket that is your power source.

Run the cable along the top of the skirting board as far as you can. If one of the sockets is higher than the other, avoid the temptation to plan the run so that the cable runs diagonally across the wall — if you do, it is much more likely that someone may accidentally puncture the wires at a later date. Mark out the route, including the new socket position, using a piece of chalk and a wooden straightedge. Measure and note the distance between the outlets.

What you need for the job

As well as the new socket and fixings you will need a length of cable to take power from an existing supply. Ask for 2.5mm2 ‘twin and earth’ and always get a few metres more than you actually need. You will also need to buy some PVC earth sleeving. This is green/yellow in colour and is used to cover the earth wire and prevent it accidentally touching one of the other wires or the backing box. Buy a box of cable clips to hold the cable in place, and a rubber grommet to protect it where it enters the new socket.

Any damaged areas must be made good afterwards with plaster. Use either readymixed plaster which you can buy in large tubs from most DIY stores or purchase a small bag of finishing plaster to mix up your own. If you are installing a flush socket in a stud or timber frame wall you will also need a small piece of plasterboard and some clout nails to patch up the damaged wall before you finish it by plastering the cracks.

Starting work

Before you start work, cut the power at the mains consumer unit. Just to make sure that you really have cut off the supply, test the existing socket with a mains tester screwdriver or plug in an appliance such as an electric lamp.


  • Before you add an extra socket, make sure that you do not overload the circuit.
  • On a ring circuit you can safely add a socket provided that the existing circuit you intend to ‘tap’ does not exceed a floor area of 100 sq m — and that you do not go outside this area when you fit the new socket outlet.
  • On a radial circuit the floor area served by the existing circuit must not exceed 20 sq m. Any new socket must be fitted inside this area.
  • Never draw power from a fused connection unit or from an appliance which has its own individual supply.

Safety first

Electricity is dangerous if you do not treat it properly. But as long as you make sure that the current is switched off before you touch any electrical fitting you cannot possibly get a shock.

Before you start work, switch off the house power supply with the main switch on the consumer unit or fuse board. A final check which will guarantee that any particular wire is disconnected is to use a mains tester screwdriver. This is an insulated screwdriver with a small neon bulb in the handle. If the blade of the screwdriver is held against a live wire the bulb lights up when you touch the handle.


Australian and New Zealand law requires that all electrical work be carried out by a licensed electrician.


  • Start with the outer sheathing. Slit the sheath lengthways with a sharp penknife or trimming knife. Don’t cut back too much — about 75mm should be adequate. Peel back the sheathing like the skin of a banana and cut off the waste.
  • The best way to strip the live and neutral wires is with a wire stripper — a cheap, easytouse tool you can buy from any DIY store. At a pinch, you could cut around the insulation with a knife; but take extra care not to nick the wires. Don’t use pliers
  • they are too difficult to control accurately.
  • Adjust the wire stripper until the blade just begins to cut through the insulation; then pull gently towards the wire ending so that the insulation is removed and a length of the inner core exposed. Trim back about 20mm on both the live and neutral wires.


  • Connect the wires to the back of the faceplace as shown above. Cut off a 55mm length of sleeving and slip it over the end of the bare earth wire.
  • When wiring the new socket (or fused connec tor) double over the end of each wire so that it is gripped more tightly (and safely) in the terminal.
  • On the existing socket, twist each pair of wires together with pliers before making the electrical connections to the relevant terminals.


  • Start by fitting the backing box in place using impact adhesive or plugs and screws. Then measure and cut the backing pieces to length — use a junior hacksaw — and fix them in position as you did the box.
  • Feed the cable into place making sure there are no twists or kinks (some manufacturers supply small clips which are spaced along the top of the conduit to hold the cable tightly). Lead the cable into both backing boxes, strip the ends and make the electrical connections to each socket
  • Trim the conduit covers to length and snap them into place on top of the backing pieces (fit angled adapters as well, if supplied). Screw both faceplates into position, then turn the power back on at the mains.
  • TIP: Disguise plastic conduit by painting it the same colour as the skirting board or achitrave it runs along.


  • Make your channel just wide and deep enough to accommodate the cable. If you are fitting a flush-mounted socket, cut out a recess about 78mm deeper than the backing box. Fix the box in place using screws and wall plugs.
  • Thread a length of cable into the channel and secure it every 300mm with cable clips. Knock out one of the cable entry blanks, add a grommet, and feed the cable into the backing box of each outlet. Strip the cable, bare the wires and attach them to the terminals on both sockets.
  • To repair damaged areas, load your plaster on to a small board and stand near the wall. Pick up a small amount of plaster on a filling knife and press it hard into the channel.
  • Once the damaged area has been filled, place a timber straightedge across the face of the wall and move it slowly backwards and forwards in a sawing motion. Work up and down the wall so that the plaster is smoothed off neatly. Sand any ridges when it is dry.


1.Cut the chase, angling the chisel in the direction you want to go

2.An easy way to cut a recess for the backing box is to loosen the brickwork first by drilling a number of closely spaced holes 78mm deeper than the box

3.Level the plaster with a straight-edge. Draw it back and forth in a sawing motion.


  • On a frame wall, start by cutting away a section of wall boarding around the proposed outlet with a sharp knife and straightedge.
  • The hole should be about 300mm high and just wide enough to halroverlap the uprights on either side. Skew nail a trimmer between the uprights to accommodate the backing box then cut a recess for the box itself with a mallet and wood chisel.
  • If the existing socket is directly below the new outlet, making the correct electrical connection is relatively easy. Simply drop a length of cable down the cavity. Then remove the existing socket faceplate and backing box and pull the end of the cable through the gap in the wall.
  • In most cases, however, you will want to lead the cable to an existing socket some distance away. The easiest and quickest way to do this is to drop the cable down the cavity and then lead it behind the skirting board.
  • Push a bolster or large bladed screwdriver down behind the skirting board and lever it gently away from the wall. Drop the cable down from above and retrieve the end (fig. 2). On most walls there will be a small gap between the wall boarding and the floor if not, cut away a section with a trimming knife large enough to reach the cable. Then lead the cable along the wall. Secure it with cable clips as close to floor level as possible. This will avoid nailing through the cable when the skirting board is replaced. Make the electrical the wires and attach them to the terminals on both sockets.
  • Patch up the damaged area around the socket with a small piece of plasterboard. Cut out a small square hole in the middle of the board to accommodate the backing box and nail it to the uprights and to the new trimmer with clout nails. Then make good the area around the socket with filler.

Mount the socket on a trimmer — a length of 100mm X 50mm sawn timber nailed between the studs

1. Make sure the trimmer is correctly aligned then skew nail it firmly on both sides. Cut a recess for the backing box and screw it to the trimmer. Make sure that the leading edge of the box is level with or just below the original wallcovering

2. If you cannot reach the cable when you drop it down the cavity, retrieve it with a piece of coathanger wire.

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