Light Will not switch off after changing switch

10 Nov 2020
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United Kingdom
I hope someone can help I changed an older 2 gang 2 way switch for a new one and now the hallway light will not switch off. I did make a note of the old settings but they don't work either (I must have made a mistake).

There are 3 (3 core) cables coming in to control an outside light and a hallway light, also controlled by a 3 gang hallway switch.

As mentioned the 1st cable is for the external light, the 2nd contains the live feed and the 3rd goes off to the hallway light switch.

The 1st cable is for the outside light and the black and blue wires are not used. The red wire is connected to COM (the external light works fine and switches on and off. There is a jumped red wire coming from the live feed from L2 on the 1st gang.

In case the picture is not clear I have wired as follows:-
Com - Red (from hallway light)
L2 - Red/Yellow (from live feed) plus jumper to L1 on other gang
L1 - Yellow/Blue (from hallway light switch)

Not sure where to go with this, so any help would be very much appreciated.

My 1st post!


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Have you got a red, yellow and blue all with black tape markers on?

Do they belong to the same cable?

If so, the yellow and blue in the same terminal looks odd to start with.
Thanks for your reply and sorry I should have taken the tape off it was just to help me locate the cables, the tape has no meaning.
I have now got the light switch working both the external light and the hallway light 'properly' but the 3 gang hallway switch cant control the light at all. I separated the yellow wire from the live feed and moved it to com (with a red wire) on gang2. This switch now appears to operate correctly with the exception of the hallway 3 gang switch - one step forward, one step back!


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Some twin switch plates have one switch upside down.

up and down switches.jpg

The switch in your photo same both switched the same way up.

If your old switch plate had one switch upwards and one switch downwards then you will need to invert the wires to the switch that is not working.
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Thanks for that the old switch is indeed one up and one down as you say. So inverting is the 1st thing I will try in the morning, so in practice is it L1 to COM, I guess I can't invert L2.


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