The England and Wales Building Regulations do not require minor changes to your home’s electrical system to be done by a qualified electrician. However, all work must meet standards outlined in the Wiring Regulations and, frankly, if you’re in any doubt whatsoever, you’d be mad not to seek professional advice before attempting electrical work.
It is also important to note that the colours of the “core” wires inside your home’s electrical cables (used for all hidden, fixed wiring) have changed over the past four years to align with the rest of Europe. This is extremely important if you plan to carry out even the simple task of changing a basic light switch or plug socket. Whenever you do this (and read up before you do), study how the wires are attached before detaching them, and if necessary draw a diagram to ensure you reconnect the wires correctly.
Note: Before you start either job, you must switch off your home’s power at the main fuse box. To be extra safe, isolate the particular circuit you wish to work on by removing its circuit fuse (and putting it somewhere memorable!) or switching off and locking the relevant circuit breaker. You can check that the circuit is dead using a plug-in socket tester or, for a lighting circuit, a voltage tester.
Changing a light switch
A single, one-way light switch is the simplest arrangement of all: one light is controlled by just this one switch, making replacement of the switch relatively simple.
Once you are certain the power for this circuit is off, unscrew the switch “faceplate” and gently pull it out so you can see the connected core wires behind.
The faceplate of a single, one-way switch has two terminals: “L1” is the terminal to which the neutral core wire is attached – the blue wire (traditionally black, before the change). “COM” or “Common” is the terminal to which the live core wire is attached – this is the brown wire (formerly red). In photo B, you see a single, one-way light switch with old-coloured wiring.
The earth wire (whose yellow-and-green colour is unchanged) should be fixed to the earthing terminal of the light switch’s metal mounting box. If this is properly attached, you don’t need to detach this to change the light switch. Simply release the live and neutral terminal screws, pull the wires out and connect them to the (correct!) terminals of the new switch. If you are in any doubt, draw a diagram before detaching the old switch.
Warning: You must take extreme care when dealing with two-way or multi-way light switches, where more than one switch in the circuit controls the same light. Don’t change these without doing serious homework first …
Changing a plug socket
Again, the core colours have changed, from red to brown (live) and black to blue (neutral). Use a socket tester to double check the socket is dead before unscrewing the faceplate and freeing the neutral and live core wires. Connect the live core wire (or wires – there are usually two, and can be three) to the live terminal (L) of the new faceplate, the neutral to the neutral terminal (N) and the earth (yellow/green) wire to the earth terminal.
Tighten the terminal screws and fit the new faceplate. Finally, use the socket tester again to check the socket is wired correctly. If in any doubt, call an electrician.