Replacing 2-gang 1-way light switch with dimmer switch

25 Jun 2021
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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 terminals the wires should go to in the new dimmer switch I would greatly appreciate it.


My current switch to be replaced:

New dimmer switch to be installed:

New dimmer switch instructions:
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Not surprised you are having difficulty. You appear to be a wire short.

What does the present switch operate?
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 been loose.

The loose wire was most likely in the B1 terminal.

The correct wire layout of the switch i'm removing is this:

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NEW... I doubt you'll get 1&2 twisted together and the link wire (3 wirew) in a terminal so chances are they will need to be split apart and wired like this
I suggest you put the old switch in with the guessed wiring, and check it is working as expected, before you connect up the dimmer.

If the wiring is wrong you could knacker the dimmer.
And it does not appear that you have earth wires in the lighting wiring.

If this is the case, you should replace all Class I luminaries and switches with Class II.

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