How to Wire a Two-Way Light Switch in the U.K.

Updated July 20, 2017

When wiring a two-way light switch for U.K., you can replace an existing light switch cover with a new one without having to call in professional help. A two-way light switch controls one light from two different positions. They can often be found in rooms with multiple entranceways, such as kitchens that have both an internal and an external door. Rewiring of light switches is one of the few electrical jobs a U.K. homeowner is allowed to undertake. Any other electrical installation has to be completed by a certified professional under the Building Regulations Part P, which covers England and Wales and relates to electrical work.

Turn off the electricity supply to the light switches in your home by turning the power off in the consumer box, which controls your home electrics. A modern consumer box will have a number of labelled switches for controlling lights and electricity points, and a main power switch, which is usually larger and red. Turn off all of the switches for the controlling lights.

Turn the light switch on and off again to check that power to that switch is turned off.

Unscrew the screws on your light switch plate and discard.

Move the switch plate so that it comes away from the wall. If the wall around the switch has been wallpapered or painted, running a craft knife around the edge of the plate wall help to loosen it.

Make a note of the positioning of the wiring behind the light switch. Pay particular attention to the three wires that go into the back of your two-way switch, as these need to be replaced in the same positions on the new switch. The one at the top of the switch is the common wire and is the main live wire into the switch. The two wires positioned at the bottom of the switch are called the L1 and the L2, and these are the wires that control whether the lights are on or off.

Unthread the common wire by loosening the screw on the back of the light switch and pulling the wire free.

Push the common wire into the correct position on the new light switch and screw in place. It should now securely occupy the slot at the top of the switch, with no bare wires showing.

Repeat the unthreading and reattaching of wires until all three have been transferred to the new switch. The old switch can now be discarded.

Hold the new light switch in place over the switch box, the metal box at the rear of a light switch that will still be in place inside the wall. All wires should be tucked inside.

Screw the light switch into position with the two screws that came with the new light switch kit. Screw until they are fixed fully in place.

Turn the electricity to the light switch back on at the consumer box. Test that the light switch is fully working by turning it on.


Care should be taken when working with electricity in the home. If a plastic light switch is being replaced with a metal one, a certified electrician will have to do this job because metal light switches need to be earthed and plastic ones don't.

Things You'll Need

  • Screwdriver
  • Craft knife
  • Light switch
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