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How to Fit Replacement Wall Switches

Although it sounds daunting, some electrical work is straight - forward to tackle on a DIY basis. Follow our simple step-by-step guide to replacing a light switch.

ELECTRICS MASTERCLASS: What are you allowed to do?

Since the introduction of Part P, there has been some confusion amongst DIY enthusiasts about what they can and cannot do themselves when it comes to electrics. In fact, you can carry out most electrical jobs yourself, but for certain jobs you will be required to tell your local authority’s Building Control department before you begin the work. You do not have to notify Building Control about:

  • repairs, replacements and maintenance
  • extra power points, lighting points or other alternations to existing circuits (except in a kitchen, bathroom or outside)

You will need to tell them about most other work. When carrying out DIY electrical work it is always best to get a competent electrician to make sure the work you have carried out is safe.

TOOL LIST

  • Insulated flat-blade screwdriver
  • Multimeter
  • Wire strippers

Replacing a Wall Switch - Step 1Replacing a Wall Switch - Step 2

1. Begin by switching off the lighting circuit power at the fuse box (consumer unit). Older and extended properties may have more than one lighting circuit, so make sure you turn off the right one.

2. Double-check the circuit is not live by simply flipping the switch to ‘on’. If the switch was operating the light before the power was turned off, and it does not come on now, you’re OK. Before you unscrew the old light switch, use a sharp blade to separate the switch body from paint that may have dried on the switch during decorating. This will help prevent any paint being pulled from the wall when removing the switch.

Replacing a Wall Switch - Step 3Replacing a Wall Switch - Step 4

3. Loosen the screw on the common/com terminal of the old switch and pull out the brown wire.

4. There will be a common/com terminal marked on the new switch. Push the wire into this common/com terminal and tighten the screw.

Replacing a Wall Switch - Step 5Replacing a Wall Switch - Step 6

5. Loosen the screw on the L1 terminal and pull out the blue wire. The new switch will be marked with ‘L1 terminal’ (and ‘L2 terminal’ if it is/will be used as a two-way switch as well). Push the blue wire into the L1 terminal on a one-way switch and tighten the screw. If you are using a two-way switch on a oneway circuit (as here), push the blue wire into the L2 terminal and tighten.

6. Some switches have an additional earth connection that leads from the back of the faceplate to the metal wall box. Bare the earth wire and connect it up to the earth terminal on the wall box.

Replacing a Wall Switch - Step 7Replacing a Wall Switch - Step 8

7. For a two-way circuit, the switches are linked by a cable with four wires: brown, black, green/yellow and grey. At one end of the circuit, these are positioned (SEE PICTURE) with brown leading from to common/com terminal, black to the L1 terminal and grey to the L2 terminal. The earth connection from the cable should already be made, but remember to make the additional earth connection from faceplate to wall box (as in step 6) if necessary.

8. At the other switch you’ll find two cables. One will be the other end of the link cable you connected up in the last step, the other will be the switch cable from the light fitting. This will contain three wires: brown, blue and green/yellow. Connect the brown wire from the linking cable to the common/com terminal, the black wire and the brown switch wire to the L1 terminal and the grey wire and the blue switch wire to the L2 terminal. The earths should be connected to the wall box, but make any additional connections from faceplate to wall box if necessary.

Replacing a Wall Switch - Step 9

9. Pull on each wire to ensure each is secure in its terminal, then push the faceplate onto the wall, taking care not to trap any wires. Push in both screws and tighten. Turn on the power and test the switch.