The present switch operates two separate ceiling bulbs, one on each switch.
There was another wire in the back box, it must have slipped out of its terminal as I was opening the faceplate. I thought it was a separate earth wire and not part of the switch wiring, the terminal screw must have...
I'm trying to replace a 2-gang 1-way light switch with a dimmer switch.
I've never replaced a switch before, hoped it would be straight-forward but I can't figure out the correct terminals to use for a 2 gang switch, all diagrams just show a 1 gang switch.
If someone could let me know which...