I live in a Victorian house and am replacing a 2 gang light switch that contains two modules (i.e. each module is a two-way switch) that has a fair amount of complex wiring. One of the old modules has 4 holes to put wires in (including the live switch wire) and the other module has 3 holes to clamp the wires in. enter image description here

enter image description here

The replacement 2 gang switch has a much more simplified wiring configuration using L1, L2, and COM and I am uncertain as to how to know which set of wires from the old switch go where in the new switch (see below). I do know that the combined earth wires connect to the back of the mounted box.

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enter image description here

So my question is, can someone help me with getting the right wires in the right holes? Many thanks in advance!

  • There are many ways to do 2-way switching. That drawing is only one of them, and a fairly rare one. Commented Aug 11, 2021 at 17:35
  • That's the instructions that came with the new switch. This is why I am a bit flumoxed! Commented Aug 11, 2021 at 17:39
  • In your pic of the old pair of switches the left switch has four holes for wires. This means to me that this is not a simple "2-way switch". Each switch in the new pair of switches has three holes and appears to be a standard 2-way switch. Is this in the UK? We need more info on the setup. Do you have two sets of two 2-way switches with a double gang in the middle and two single gangs on the outsides? Is this a hallway (perhaps L shaped) with lights in each stroke of the L? Commented Aug 11, 2021 at 18:57
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    @StaceyDeAmicis Those instructions are for wiring a new 2-way circuit, when you're doing it from scratch with all new wires. And in particular, that one is for the case where power comes into the lamp and the switches are on a spur. There are other ways to wire that situation. And many other possible situations. And you may be dealing with two of them in this very box! Commented Aug 11, 2021 at 22:02

1 Answer 1


You have the wrong replacement switch

Your existing switch isn't a 2-way/2-way two-gang assembly like you thought it was, it's actually a 2-way/intermediate (North American translation: 3-way/4-way) two-gang assembly. So, you'll need to get the correct switch before you go any further with this.

  • Yeah, I was looking at the drawing and enhanced it in Photoshop, and I was looking at the diagram at the far left, and was like "SS Botany Bay... SS Botany Bay!!!" Commented Aug 12, 2021 at 3:20
  • Ah ha! No wonder it wasn't really making sense to me. Thank you! Commented Aug 12, 2021 at 10:50

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