Two-gang switch wiring: two lights from one place

A two-gang (double) switch has one line input (L) and two outputs, one for each light (marked 1 and 2, or 1 and 3, depending on the maker). Only the line goes through the switch; neutral and earth are joined in the box and run straight to the light fittings. A chandelier with two circuits needs a cable with two line cores plus N and PE.

Two-gang (double) light switch wiring diagram

For 230/400 V installations to IEC standards (Europe, UK and most of the world). North America uses different voltages, colours and rules: see the “Around the world” notes.

The rule: you only switch the line

A two-gang switch is essentially two ordinary switches in one plate, fed from one line. Each rocker connects the line to its own output:

Terminal	What goes there
L	incoming line (supply)
1	switched line to the first light
2 or 3 (depends on maker)	switched line to the second light

Neutral (blue) and earth (green-yellow) do not enter the switch. Join them in the box and take them straight to the fittings. Check the terminal markings on your specific switch.

Two-gang switch diagram: line to terminal L, two outputs to two lamps, N and PE straight to the fittings — One line input, two outputs, one per light.

Two separate lights (for example main light and wall lights)

The supply (L, N, PE) comes into the box, and a three-core cable (switched line, N, PE) runs to each light. In the box:

all PE together,
all N together,
supply line → switch terminal L,
line core to light 1 → terminal 1, to light 2 → the second output.

Chandelier with two circuits

If both rockers control one chandelier (for example half the bulbs or all of them), the cable from switch to fitting needs two line cores, N and PE, so four cores. Inside the fitting each line feeds its own group of lamps.

Common mistakes

Neutral switched instead of line: the lamp goes off, but the fitting stays live.
Outputs swapped: the rockers work "crosswise" (harmless, but fix it).
Not enough cores to the chandelier: with three cores you only get one circuit.

Around the world: UK "2-gang 1-way switch"; USA "double switch" or "double rocker". Controlling the same light from two places is a different circuit: two-way switching.

Important: isolate the circuit at the board and prove it dead before you start. In old installations with unusual colours, check every core's function with a tester.