Helpful video reference. We use this switch plate wiring tutorial as the video reference for this guide. The written steps below extend the content to cover both 1-way and 2-way gangs and the earth checks that matter on metal back boxes.
1. Count the cables and identify circuits
Ease the plate carefully away from the back box, pulling gently to avoid dragging cables out with it. Count the cables entering the box from the back or sides.
A 5-gang plate might have:
- Five switch drops, one per gang (the most common arrangement for a 1-plate wiring method).
- A mix of switch drops and strapper cables (for 2-way gangs sharing a light with another switch elsewhere).
- Occasionally, a junction in the back box where more cables are looped.
Work out which circuit each cable belongs to before you isolate anything. Tracing the cables to their MCBs now saves confusion later.
2. Isolate every circuit
At the consumer unit, switch off each lighting circuit MCB or fuse that could supply this plate. With five gangs you may need to switch off several MCBs.
Come back to the plate and test every conductor in the back box with an approved voltage tester: between each conductor and earth, and between all conductors. Do not begin disconnecting until every test reads zero.
If you share the back box with any other accessory (a data point, an aerial socket) those cables may come from entirely different circuits. Leave those alone unless you know exactly where they come from.
3. Photograph the back box
A well-lit photo of the back box before you disconnect anything is the single most important step on a 5-gang plate. With five gangs, multiple cables and terminal strips, it is very easy to put a conductor back in the wrong place.
Take the photo, zoom in, and check you can read every terminal label and trace each conductor from its insulation colour to its terminal on the old plate. If the existing plate has worn terminal markings, note them down before you remove the plate entirely.
4. Identify each gang type
On the old plate, check the terminals on each gang:
- 1-way gang: Common and L1 only. Controls one light from this switch alone. The conductors are typically a brown (common) and a grey or black (switched live, re-identified with brown sleeve).
- 2-way gang: Common, L1 and L2. This gang shares control of a light with another switch at the far end of a strapper cable. Stairs and long landings are the common locations.
If you are replacing an old plate that has 1-way gangs with a new plate that has 2-way gangs (common with replacements using modern twin-rocker plates), you can wire the unused L2 terminal by linking it to Common with a short brown conductor, which converts it back to 1-way operation.
5. Wire each gang, one at a time
Do not remove all the conductors at once. Transfer them one gang at a time:
- Loosen the first terminal on the old plate, remove the conductor, and connect it to the matching terminal on the new plate.
- Tighten firmly and tug the conductor to confirm it is secure.
- Repeat for each remaining conductor on that gang.
- Check your photo to confirm the terminal labels match.
- Only then move to the next gang.
Five gangs takes longer than four, but the method is the same. Patience here avoids an hour of fault-finding after you restore power.
6. Check the earth connections
Every earth conductor in the back box must connect to the earth terminal on the faceplate. If the back box is metal, also fit a flying earth lead from the plate earth terminal to the dedicated earth terminal on the back box. This is required by BS 7671 and is commonly missed.
On a 5-gang plate with a large footprint, check that the back box is deep enough. A 47 mm deep metal back box is usually required for a 5-gang plate with multiple cables. If the plate is sitting proud of the wall or the cables are jammed, a deeper box is the solution.
7. Refit and test every switch
Fold the cables gently into the back box. Check no insulation is caught under the edge of the plate before tightening the fixing screws. Tighten the screws evenly so the plate sits flush.
Restore power to each circuit one at a time and test every switch position:
- 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 elsewhere.
If any switch fails, isolate that circuit at the consumer unit before reopening the plate. Do not try to re-examine live wiring in the back box.
When to call us
Five gangs from a single plate is usually found in kitchens, hallways or media rooms where a lot of circuits meet at one location. If the plate has accumulated extra cables over years of alterations and does not match any obvious wiring pattern, it is quicker to ask Richard to trace the circuits than to guess at them.
Need a switch plate fitted in Sandwich?
Richard fits standard and bespoke switch plates at a fair local rate, including multi-gang plates and smart switch upgrades.
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