Helpful video reference. GSH Electrical (Nick Bundy), one of the UK's leading electrical training YouTubers, demonstrates wiring a 4-gang 1-way switch. The written guide below extends this to cover 2-way gangs and mixed plates, which are more common in practice.
1. Understand what you have before disconnecting anything
Ease the plate away from the back box and count the cables. A typical 4-gang plate might have:
- Four switch drops, one per gang, each with a switched live and a common live (a 1-plate arrangement).
- Four switch drops where each gang has a Common, L1 and possibly L2 (a 2-plate arrangement for 2-way switching).
- A mix: some gangs 1-way, some 2-way.
Count the conductors and look at the terminal labels on the old plate. Take a clear photo before you disconnect a single wire.
2. Isolate every circuit
Switch off all lighting circuits that might feed this plate at the consumer unit. Come back to the plate and test with an approved voltage tester between every conductor and earth, and between conductors. Do not begin disconnecting until every test reads zero.
If the plate shares a deep back box with other accessories (a BT socket, for example), be aware that those cables may come from completely different circuits.
3. Photograph the back box
A well-lit photo of the wiring before you disconnect anything is not optional on a 4-gang plate. You have multiple cables in a limited space and it is very easy to reconnect a conductor to the wrong gang when everything looks similar in the bottom of a back box.
Take the photo, zoom in and check you can read the terminal labels and trace each conductor from its insulation colour to its terminal.
4. Identify each gang type
On the old plate, look at how many terminals each gang uses:
- 1-way gang: Common and L1 only. Controls one light from this switch position alone.
- 2-way gang: Common, L1 and L2. Shares control of a light with another switch elsewhere (stairs, long landings, double doors).
If you are fitting a new plate with 2-way gangs to replace an old plate with 1-way gangs, you can wire L2 with a short loop of brown wire (a link) between L2 and Common, which converts the 2-way gang back to 1-way operation. Some fitters simply leave L2 empty - the light will work but the gang is wired incorrectly for 1-way use on most plate designs.
5. Wire each gang, one at a time
Transfer conductors from the old plate to the new plate one gang at a time. Do not remove all the conductors at once - you will lose track of which cable goes where.
For each gang:
- Loosen the first terminal on the old plate and move the conductor directly to the matching terminal on the new plate. Tighten firmly.
- Tug the conductor - it should not pull out.
- Repeat for the remaining conductors on that gang.
- Check your photo to confirm you have matched the terminal labels correctly.
- Move to the next gang.
6. Check the earth connections
Every gang that has a metal faceplate or metal rocker must have the earth conductor connected to the earth terminal on that gang (or a common earth bar on the plate). Plastic faceplates still need the earth connected to the plate earth terminal if one is provided.
If the back box is metal, fit a short flying earth lead from the plate earth terminal to the earth terminal on the back box. This is required by BS 7671 and commonly missed.
7. Refit and test
Fold the cables gently into the back box without pinching any insulation under the edge of the plate. Tighten both fixing screws evenly. Restore power to each circuit one at a time and test every switch:
- For 1-way gangs, the light should operate from this plate only.
- For 2-way gangs, the light should operate from both this plate and the paired switch at the other end of the strapper cable.
If any gang does not operate correctly, isolate that circuit at the consumer unit before opening the plate again.
When to call us
If the plate feeds a staircase or hall where the circuits have been extended over the years, the wiring can be more complex than a standard 4-gang job. A fresh set of eyes from a qualified electrician takes an hour and avoids an afternoon of frustration.
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