LED Dimmer Switch and Wiring help

Mar 30, 2024
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United Kingdom
Hello All - Looking for assistance with wiring my Collingwood LED lights to a dimmer switch with L1, L2, and COM ports.

I have a Collingwood LED Lights (x 3) and single (x 1) Mirro in my bathroom.

I need to install a new 20w 2 Way Silent Trailing Edge LEDlite Dimmer - Module switch to dim the lights.

I am having trouble how to wire it up.

I have a L1, L2 and COM ports on the dimmer switch. The bathroom has 3 ceiling lights and a mirror light, 4 in total. Can someone help?

The old 2-way switch setup is attached, note 5 red wires and 1 yellow.

Does the 1 yellow fit into the COM Port and the other 5 red into L1 and L2?


Dec 19, 2010
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Not really safe to make a suggestion.

Old colour three core and earth used for UK 2-way lighting was made up of earth, blue, red and yellow.

Old wiring like yours would have black and red cables and occasionally earth and two reds.

The reds are likely to have a supply in and out if daisy-chained and possibly a drop or connection to the plate switch.

Electricians often don't stick to the rules and change colour usage.

You can identify cables with a meter, but I can't recommend it. If you do have a go, mark all your cables with a marker pen - I use bars or even binary code - and take plenty of photos. Try an ordinary plate switch to test then fit the dimmer when the 2-way lighting works with the plate switch.

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