If you need to fit a new electrical accessory onto a wall that is made of plasterboard a dry lining box like this would be used-
These dry lining mounting boxes are very easy to use and sit flush against the surface of the wall, in this example we are fitting a double accessory box.
First you will need to measure the height you want the electrical back box to be fastened at. Then using the spirit level and making sure it is straight, draw a line.
Push the blue lugs into the box, see picture. Hold backbox up to the sraight line and use a pencil / maker to draw a line around it.
The back box outline is now on the wall and ready to be cut-out.
Next the plasterboard needs to be cut using either a Stanley Knife, Plasterboard Saw, or a Rotozip, this example is shown using a Stanley Knife. Cutting the outline is fairly easy. Make sure you take your time and after you have run the blade around a few times the blade will cut through producing a good clean cut-out.
Once you have completed the cut-out it should look something like this.
Next push lugs into the accessory box and then fit the accessory box into wall. If the box does not fit, try shavhing the edges of the cut-out with a knife to obtain the correct fit.
This is the correct way an accessory box should look once fitted into the plasterboard. Tighten the accessory box screws so that the lugs grip the plasterboard.
Fitting a Surface Mounted Patress Box
As the patress is surface mounted, this means the fitting will stick out and therefore can be subject to damage from knocking etc. The patresses are the easiest of back boxes to fit by simply using screws and fixings to attach to wall.
This is the correct way an accessory box should look once fitted into the plasterboard. Tighten the accessory box screws so that the lugs grip the plasterboard.
As you can see in the picture the patress has the wire being fed from the wall into the back of the box and is screwed to the wall.
Fitting a Metal Galvanised Backbox
Back boxes have many depths suitable for different things. A 16mm deep box is used for light switches but is too small for a shower circuit. A 47mm deep box is almost 3 times the depth and more suitable for a shower circuit, but far too deep for a light switch.
Back boxes must be set at the correct level and also sunk to the right depth. Normally you will not have a problem with this unless the area you are sinking the box into is in poor condition.
Regulations for new houses state that you must have your switches & sockets at the correct reg height, for adding to your own home you can place the new sockets/switches at the same height as the exisiting fittings.
First things first, measure the distance of a current socket in your house from the floor.
Then where you want your new socket to go, measure the distance from the floor and draw a line using a spirit level to mark out the new socket.
Once you have done the above find the back box you are going to use and hold the box up to the previous line you drew and draw around the whole of the box. Now you are going to need a hammer drill, a masonary drill bit and some electrical tape. Measure the depth of the back box against the drill and mark the drill bit with the tape so you drill the exact depth of the back box. Next job will be to drill a series of holes where the back box will sink.
Now "Pepper pot" the inside of the lines that you have drawn using the hammer drill.
Next you will need to chisel the masonry away using the a bolster chisel to hammer to correct depth. Be careful as old plaster or poor brickwork can be very tricky resulting in damage and large amounts of plaster coming away!
A cut-out should look like the picture to the left, if more plaster falls away you can repair this quite easily. In the instance above a plasterer is plastering the whole room, this would be the best time to add sockets/switches.
Next you will need to tap out one of the knockouts and fit a grommit (see below) in before you sink the back box into the wall.
To your left is an example of a grommit.
Lastly you will need to sink the back box into the wall, drilling two holes and securing the box using screws and wall plugs. Once done clean up surrounding area with plaster or a suitable filler for an overall professional look to your job.
