3 Gang Switch - advice needed

[PaulL76]

Hello,

I wondered if someone with more experience of this than me might be able to help.

In our porch there has been a 3 gang switch since we moved in, one of which turns on an outside light (switch on plate closest to door), another the light inside the porch (middle switch) and the third (switch on plate furthest into room - near door into kitchen) appears to be redundant. I suspect that in days gone by it may have been another switch that controlled the kitchen light.

Since decorating the porch I had aimed to replace the 3 gang switch with a 2 gang but on unscrewing the front plate I am very confused by how it is wired up.

The 2 functioning switches are fairly straightforward but I can't work out what is going on with the switch that apparently doesn't do anything...

I have drawn a diagram and uploaded to help but basically the two functioning switches have a black and red each while the third switch has a red connected to common, a yellow to L1 and and blue to L2.

Untitled

• PaulL76
• 2 Nov 2014
• 1

If anyone has any thoughts on this I would be really glad to hear from you.

Many thanks,
Paul

 

[EFLImpudence]

It is wired as it would be if it were one of two switches which operate the same light.

Stairs ???

 

[ban-all-sheds]

The unknown/non-functional switch is one of what was a pair of 2-way switches.



Just put the conductors into a 3-way bit of choc block.

 

[PaulL76]

Many thanks both of you for your fast replies. This porch is in part of the house that was extended, I guess the other switch and lights are no longer part of the circuit on the unknown switch. Choc block it is then.
Thanks again,
Paul

 

[Jackrae]

You might find that the switch - even if apparently doing nothing - is in fact part of an existing lighting circuit and that either position is "required" to permit the light to operate from some other switch (which is possibly incorrectly wired)
If that is the case then putting the wires into a 3-way terminal block might stop the mystery light from working.
Should that happen and you want to leave things working as-is then simply bridge the red wire to either the blue or yellow.
The correct solution would of course to be identification of the defect and correcting it.