A 2-gang light switch (also called a “double light switch”) is a single faceplate with two independent switches on it. Each switch (or “gang”) controls a separate light fitting. Common uses: a kitchen ceiling light plus an under-cabinet light from the same wall switch; a hallway and landing light at the bottom of the stairs; a bedroom main light and a wall light; the ceiling light and an extractor fan in a utility room.

This guide covers the standard UK arrangement – a 2-gang 1-way switch where each gang acts as an independent 1-way switch, in accordance with BS 7671:2018 (the IET Wiring Regulations, 18th Edition). Each gang can also be wired as part of a 2-way arrangement (a 2-gang 2-way switch); the principles in this guide combined with the 2-way wiring guide cover that case too.

About the terminals on the back of a UK 2-gang switch. Most domestic UK 2-gang switches sold today have six terminals on the back (COM, L1, L2 per gang) even when they’re labelled “2-gang 1-way”. Manufacturers use the same internal mechanism for 1-way and 2-way and just leave L2 unused in the 1-way configuration. So when wiring as 1-way, you connect to COM and L1 only on each gang – L2 stays empty. Some budget switches do ship with only four terminals (COM + L1 per gang); the wiring is identical either way.

Notifiable work: replacing an existing 1-gang or 2-gang switch like-for-like on an existing circuit is generally not notifiable under Part P of the UK Building Regulations. Adding a new switch position, working in a special location, or modifying the consumer unit usually is. If in doubt, use a Part P registered electrician.

Before you start: safety

1. Isolate the lighting circuit at the consumer unit and verify dead at the switch using a GS38-compliant two-pole voltage tester. Prove-test-prove on a known live source. If the two lights are fed from different lighting circuits, isolate both – don’t assume one MCB covers everything in the back box.
2. Lock or label the consumer unit so the circuit cannot be re-energised while you are working.
3. Non-brown conductors used as switched live must be identified with brown sleeving or tape at every termination (BS 7671 Table 51).
4. Metal-faceplate switches must be earthed via the earth terminal on the switch plate – not just the back box.

Full safe-isolation detail is in the 2-way light switch guide.

What you will need

• One 2-gang light switch (1-way, or a 2-way mechanism used as 1-way)
• Brown identification sleeving or PVC tape for the blue cores acting as switched live
• Green and yellow earth sleeving
• Wago lever connector or approved screw terminal block for jumpering the two permanent live conductors inside the back box
• Short length of brown 1.0 mm² or 1.5 mm² solid conductor for the COM-to-COM link
• Back box at least 35 mm deep – 47 mm preferred for 2-gang switches with six terminals. A shallow box (16 or 25 mm) won’t fit the conductors comfortably and risks pinching insulation or damaging the switch
• GS38-compliant two-pole voltage tester
• Insulated terminal screwdriver, side cutters, wire strippers

How a 2-gang 1-way switch works

In a standard UK loop-at-the-rose lighting circuit, each light fitting has its own twin-and-earth switch drop running down to the switch position. So a 2-gang switch position has two twin-and-earth cables entering the back box – one from each ceiling rose.

Each cable’s brown core brings permanent live down from its rose; each cable’s blue core (sleeved brown at the terminals) takes switched live back up to its rose and on to the lamp. Inside the back box, the two browns are jumpered together using a Wago connector so both gangs share the same permanent live feed. Each blue lands on its gang’s L1 terminal. The two gangs then operate independently – toggle gang 1 and only light A switches; toggle gang 2 and only light B switches.

If the two lights are on different lighting circuits (rare but possible – e.g. a hallway light on the upstairs circuit and a porch light on the downstairs circuit), the two browns must not be jumpered. Keep each gang on its own circuit by landing brown A only on gang 1 COM and brown B only on gang 2 COM, with no link between them. This is unusual in domestic installations – if you’re not sure, check at the consumer unit which MCB controls each light.

Wiring diagram (UK)

The diagram shows the standard UK arrangement. Two twin-and-earth cables enter the back box – one from light A’s ceiling rose, one from light B’s. Both brown cores (permanent live from each rose) are joined inside the back box using a Wago lever connector or approved screw terminal block, and a short brown link wire from the Wago supplies the COM terminal of both gangs. The blue core of cable A (sleeved brown for switched live) lands on gang 1 L1; the blue of cable B lands on gang 2 L1. The two L2 terminals stay empty when wired as 1-way. Earth is bonded to the back box earth terminal and (for metal-faceplate switches) to the switch plate. Neutral remains at the ceiling roses and does not enter the switch – standard UK loop-in topology.

Step-by-step procedure

1. Isolate the lighting circuit (or circuits) at the consumer unit and prove dead at the switch. If you are not sure both lights are on the same MCB, isolate the whole consumer unit or turn off both candidate MCBs.
2. Remove the existing switch. Photograph the existing wiring first. Label each cable with masking tape – “kitchen ceiling”, “under-cabinet”, etc. – so you know which gang controls which light when you reassemble.
3. Identify the two cables. Each twin-and-earth cable has a brown (permanent live from rose) and a blue (switched live back to lamp). If the previous installer didn’t sleeve the blues, do so now – wrap brown identification sleeving over each blue at the cut end.
4. Jumper the two permanent live conductors:
   • Both brown cores into one side of a Wago lever connector (or approved screw terminal block)
   • One short brown link wire (1.0 mm² or 1.5 mm² solid) into the other side of the Wago, with its tail running to gang 1 COM and a second tail (or a continuation of the same link) to gang 2 COM
   • Alternative: use a 3-port Wago and run a short tail to each gang COM directly
5. Connect each gang’s switched live:
   • Blue of cable A (sleeved brown) → gang 1 L1
   • Blue of cable B (sleeved brown) → gang 2 L1
   • Both L2 terminals stay empty (don’t place anything in them and don’t leave loose copper exposed near them)
6. Bond all earths at the back box earth terminal. Both earth conductors should land in the same earth terminal, sleeved green/yellow where bare. Add a fly-lead from the back box earth to the switch plate earth terminal if the switch has a metal faceplate.
7. Confirm brown sleeving on both blues at every termination.
8. Gentle pull-test every termination, including the Wago connections.
9. Reassemble: tuck conductors carefully into the back box. With six terminals plus a Wago plus earths, a 2-gang back box gets crowded fast – take your time and make sure no insulation is pinched under the screw clamps and the Wago sits flat.
10. Restore power and test each gang independently. Gang 1 should switch only light A; gang 2 should switch only light B.

Common faults

One gang turns on both lights. The two switched lives are crossed at the back box – either both blues are on the same gang’s L1, or the jumper has accidentally tied a switched live to the perm-live circuit. Disconnect, re-check which cable feeds which light, and re-land.

One gang doesn’t do anything. Either the corresponding blue isn’t landed on L1 (it’s on L2 by mistake, where the 1-way mechanism doesn’t use it), or the Wago jumper isn’t carrying perm live to that gang’s COM.

Both gangs work but the faceplate sits proud of the wall. The back box is too shallow for six terminals plus the conductors and Wago. Replace the back box with a 35 mm or 47 mm deep box, or relocate the Wago into the ceiling void if there’s room there.

One MCB trips when only one of the gangs is on. The two lights are on different circuits and the browns shouldn’t have been jumpered. Undo the Wago, separate the two permanent lives, and land each brown only on its own gang’s COM.

Can a 2-gang switch be a dimmer?

Yes – 2-gang dimmers exist and replace a 2-gang switch like-for-like. Each gang independently dims its respective light. UK practice is the same as single-gang: trailing-edge dimming for LED loads, only one dimmer per lighting circuit. The wiring is identical to a 2-gang switch except the dimming knobs replace the rockers, and the load on each gang must be within the dimmer’s rated wattage (typically 10–150 W per gang for LED).

Smart control on a 2-gang switch position

The cleanest way to add smart control to a 2-gang switch position is to put a smart inline module at each light fitting. The 2-gang faceplate stays as a standard switch (or a stateless retractive switch, depending on the module); the module sits in the ceiling void or behind the rose and provides the Zigbee, WiFi, or Matter connectivity.

• SM308-S Zigbee switch module – needs a neutral at the light fitting (universal in UK loop-at-rose); Home Assistant, Hue Bridge, SmartThings, Hubitat
• SM309-S inline module – no-neutral; can act as a switch or a dimmer; fits inline at the light fitting

Install one module per gang, and you get independent smart control of both lights while keeping the familiar wall-switch faceplate.