I am getting into Lightwaverf having previously installed X10 kit in part of the house which doesn’t work all that well.
In our kitchen we have a 3 gang switch which I am thinking of replacing with a 3 gang dimmer. The exiting 3 gang switch appears to fit into the same size back box as a 1 gang switch. In the pictures of the 3 gang Lightwaverf I have seen the faceplate looks about the same length as a double wall socket. My question is will the Lightwaverf 3 gang dimmer fit into the existing back box I have or will I need a larger back box to house the Lightwaverf 3 gang dimmer?
Yep, double box needed. The Lightwave innards take up 25mm depth but not all the way to the edge, so 25mm depth is sufficient if you have enough cable length to be able to route the wires around the outer edge of the box (just done this myself).
If they need to go across the centre you’ll need 35mm depth.