Wiring problem: replacing two gang switch with two gang dimmer

[cR4cKF0x 5TevE]

As per title, I'm having some trouble matching the wiring 'convention' for the current two gang switch in my living room with a new two gang dimmer I've just purchased. One switch operates the ceiling lights, the other the wall lights. There is another, separate single switch in the living room that only controls the ceiling lights, I rarely use this and plan to leave it 'as is'.

The current switch wiring along with the new dimmer switch configuration are shown in the attachment; any ideas as to what goes where?

[Bruce_]

you don't mention what the switch is, or what the dimmer is. but it shouldn't be too difficult to work out.

the dimmer should explain which is the load and which is the supply terminal.

the switch - load is probably the ones you describe as "single red". supply if probably the ones you describe as "bridged"

not sure what the yellow wires are for. possibly just a looping point for neutral, but why the red sleeve.

if you have a meter, I suggest that you measure the voltage at each point, with the switches both on and off. the supply will be the ones that are on all the time, no matter what position the switch is in. the load will be switched on and off when you operate the switch, of course.

HTH

[Sonic67]

Difficult to say but I'd say the blue with red sleeving must be a permanent live as it is looped across to the other side of the switch to be the permanent live for that side also.

On the other side is a single red on L2 which is then a switched live.

The two yellows with red sleeving are sleeved to indicate live. Neutrals generally aren't at switches. Maybe the lives are being looped at the switches rather than at ceiling roses so they could be put together in a connector.

The single red at L1 on the left is another switch wire.

So I'd say connect the yellows with red sleeving in a connector block together.

The blue with red sleeving is probably a permanent live and so will be the live for the dimmer switch. I'm unsure what you mean on the diagram as on the right you have single red/bridge. If this is a bridging wire then it's unnecessary now. If you mean you also have a single red as well as the bridging wire then that will need to be included also.

The two switch wires for your lights (red and at the top of your diagram) will go onto the load side of the dimmer.

.... Probably. Looks a bit complicated to me. If I was there there'd be a few things I'd do.

1. Make a diagram so I can get things back to how it was before I started messing. Always essential.

2. Not entirely safe .... but switch off the lights, disconnect the lot turn on power. Test cables. From this you can see which is actually live and goes back to the board. Turn off power and mark up this cable. I use a bit of white tape folded around the cable with some left like a flag and then use pen to mark up.

3. Find out which goes to what light. You can do it safely by testing with power off - eg. short the live and earth at light, then test at the switch to see which now has the short, or less safe, leave the power on and touch the end of the switch wire to the end of the live you found. A lot quicker so it's okay for me to do it as an electrician, not for you.

[cR4cKF0x 5TevE]

Got my neighbour ound (he's an electrician) and it took him a while but its now in and working.

Many thanks.