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[Anthony Latham]

I have a problem with trying to re-wire a 2 gang, 2 way light switch that operates the light at the bottom of the stairs and the light at the top.
I can get the light at the top to work, but for some reason, not the one at the bottom.
I have two sets of cables leading to the switch. One cable has a red and black wire and the other set has one red, one blue and one yellow.
For the cable that has the red and black wires, i have wired the red into the common position and the black into the L1 position on the one switch (leaving the other L2 position free) and this works the upstairs light ok, but i am not now sure about the other 3 wires (i have tried various configurations, but to no avail).

Can anyone point me in the right direction???

Thanks :?:

[thedoctor]

See our project section, Electrical, Lights and switches. There are diagrams and examples of two way wiring in there. https://www.diydoctor.org.uk/projects.htm

[ericmark]

There is not convention on which wire does what on your red, yellow, blue wire but they do go to the same place on both switches.
You will need to look at the other switch and mimic the connections so:-
Common to Common
L1 to L1
L2 to L2
The other switch will most likely have two wires in the L1 and L2 the only really important wire is the common if L1 and L2 swapped between two switches it will still work and since they are all line wires getting wrong order will not cause any damage so if you thy three times with different wire in common each time it should work.

This is all assuming it is wired normal way. School boy two way switching is different to that used in a house as with school boy method you need a connection block in the switch. If you find a connection block in the other switch all I have said is wrong.