I’m trying to install a smart switch, from a 2 gang one way one dimmer (which worked fine) but it’s baffling me; it appears that two other rooms are affected as they both no longer work at all; I’ve installed the same switch in another room and it’s fine! In this room there’s an extra cable in this switch that’s grey in colour, whether the colour is of significance I don’t know, switching the cables around I can get power to the lights but can’t use the switch to operate them but I can’t understand why I can’t get power to the other rooms, or operate the switch oh I’m in the UK any help would be great. Cheers Dave (Sparky)
I would open up the two other switch boxes and take a look at what is going on. Then try to figure out if the switch powers the light or the line goes to the lights and then to the switch. Then check for voltage at various points. If you still can not solve the problem, put every thing back the way it was and check for voltage at various points and compare your test notes. I am not sure what you are saying but I suspect that the gray wire is the issue. It is possible a 3 way switch was installed and then removed. Also if you get a handle on when the wiring was done, someone may know about a practice that was done at the time.