Shelly 1 wiring behind 2 way switch

Cannot understand how to wire Shelly 1 to back of 2 way switch on landing
Help please
3 wires back switch common red l1 black and l2 red

See if you can make sense of

You’d need to find which of your two-way wall switches has the common wire connected to the lamp (the other wall switch will be connected to permanent live feed). But you still need a permanent live for the Shelley, so it’s probably easier to do everything at the ceiling fitting.

An even easier fix would be to install the shelly in front of the lamp, not behind a switch

No, as you normally only have a switched life wire at the lamp position.

In that case you’ll need to place it behind a switch indeed. I myself have a quite new house that was build in 2018, and behind every lamp box there is also a live wire, didn’t know that they don’t do this on all houses…

mm, yes it does depend on local practice. UK lighting tends to loop live feed in and out of every ceiling fixture, with cabling to and from wall switches below. Even when the wires were black and red.

I’ll have to wire at junction box

Derek Murton

hmerk Hans-Jörg Merk Foundation member
July 10

No, as you normally only have a switched life wire at the lamp position.

you need to “detach” the switching circuit from the lamp and attach it to your shelly. the shelly then switches the lamp.
see here