How to wire a 1-way light switch
Nearly all light switches today are 2-way light switches as they work perfectly well as 1-way switches and it’s simpler to make one version than two. If you do come across a 1-way switch, it will only have 2 terminals, one goes to live and the other goes to the light (or light group).
This is a 2-way switch (Right Image)
You can see that there are terminals labelled COM, L1, L2 and an earth terminal. Some plastic switches don’t have an earth terminal some do, all metal switches should have an earth terminal and it’s important to connect it. It’s good practice to connect the earth to the metal back box as well.
In a 1-way configuration, i.e. One light (or light group) and one switch, the wiring is quite simple. The Live wire goes to COM and the wire going to the light is connected to L1 (or L2, doesn’t matter just changes which is the ‘On’ side of the switch).
And that’s it, a wired 1-way light switch.
How to wire a 2-way light switch
On the image (top right) you can see that there are terminals labelled COM, L1, L2 and an earth terminal. Some plastic switches don’t have an earth terminal some do, all metal switches should have an earth terminal and it’s important to connect it. It’s good practice to connect the earth to the metal back box as well.
In a 2-way configuration, i.e. One light (or light group) and two switches, the wiring is a little more complicated than the 1-way. The Mains Live wire goes to the COM terminal of one switch and the wire going to the light is connected to the COM of the other switch. Then L1 and L2 terminals from one switch are connected to the L1 and L2 terminals on the other switch.
And that’s it, a wired 2-way light switch.
How to wire an Intermediate/3-way light switch
In a 3-way configuration, i.e. One light (or light group), three or more switches, the wiring gets more complicated. Intermediate switches fit between two 2-way switches as shown below.
In the same way as the 2-way setup, the COM terminals of the two 2-way switches: one goes to Live and the other goes to the light.
With intermediate switches the terminals can have different labels. Sometimes there are 2 L1 and L2 terminals, sometimes there are L1, L2, L3, L4 terminals. The important part is the L1 and L2 labels, these should connect to the L1 and L2 of one of the 2-way switches.
Then the other two terminals attach to L1 and L2 of the other 2-way switch. It doesn’t matter which way around; it only matters that L1 and L2 go to one switch and the others go to the other switch.
How to wire a socket
This is a typical double socket. You can see there are only 3 terminals: The Live, Neutral and Earth. Often there are two earth terminals, but both are not needed they are just there for ease of wiring.
Usually, sockets are wired in a ring circuit, effectively daisy-chaining them together then both ends of the ring go to the mains supply. This allows half the current to go down each path, reducing any heat build-up in the wires.
How to wire a cooker switch/double pole switch
Cooker switches and double pole switches are similar, the only difference is the cooker switch can usually carry more current, so the terminals are chunkier as are the wires that connect to them. The main difference between a double pole switch and normal switch is that both the Live and the Neutral circuit are switched off, rather than just the Live.
This completely isolates the appliance from the mains circuit. This is a safety measure in case there is a voltage on the neutral circuit, usually it’s a very small voltage but if there is an earthing fault somewhere in the property it can cause a high voltage to build up on the Neutral circuit.
This is a cooker/double pole switch (illustrated on the right).
How to wire a 2-way light dimmer
The first thing to note is that some dimmers do not support 2-way operation at all. Our standard dimmers will support 2-way operation but only one of the switches can be a dimmer. If you need multiple dimmers on the same circuit, smart dimmers must be used. For the same look we have the dummy dimmer option, where the switch looks like a dimmer but operates as a switch.
Other than those limitations, the wiring is the same as the switched 2-way circuit.
How to wire a ceiling rose light fitting
When wiring a ceiling rose fitting it’s usually easiest to start with the ring circuit loop. They are connected to each 3 terminal block. The switch is wired across the live loop and the 2 terminal block. Then the light is wired across the neutral loop and the 2 terminal block that the switch is attached to.
General Wiring Tips
Make sure each terminal is tightened to each wire, you can usually feel the wire bend as the terminal clamps it, it should bend slightly but not too much as that can snap the wire. A tug on the wire once complete will show that the wire is secure.
Any wires that run through insulation must be rated to a higher amperage as insulation will prevent them from cooling. Check with your electrician.
When using a standard twin and earth wire for connecting 2-way or intermediate switches, wrap a brown/red sleave around the neutral wire to show it can be live.
This article uses the newer brown (live) and blue (neutral) colours for domestic wiring, for older wiring the red is live and black is neutral.
Use rubber grommets on metal back-boxes to prevent the sharp edges of the back-box cutting into the wire.