1 Cutting the channel

Electrical cables must be fixed to the structure of the house. This can be in hollow voids between floors where it cannot be seen or, where they would otherwise be on 'display', cables are buried inside walls. In stud partition walls this is quite straightforward, but in solid walls, you should mark the cable runs on the plaster. Turn off the power to the circuit. Allow a channel of about 25mm (1in) wide and cut both sides with a bolster and hammer then hack out the plaster with a cold chisel.

2 Coping with obstacles

Ideally, cables should run vertical to switches or sockets. Electrical cables should never be run diagonally across walls: once covered and finished, it's impossible to tell where the cable is located and you may inadvertently nail or screw into the live cable. Where cable has to run horizontally, it must be within 150mm (6in) of the ceiling and 300mm (1ft) of the floor. Where you meet an obstacle - such as a dado rail - use a power drill to cut the cable channel behind the rail.

3 Burying the cable

Sheathed cable can be safely buried, although many prefer to bury it within a further plastic channel. The cable is secured in the channel with plastic clips nailed over the cable. Restore power to the circuit to check that the installation is working.

4 Making good

Turn off the power to the circuit. Apply plaster to the cut channel in the wall. Finish and make good the wall decoration and connect the switch/socket.