light switch old wiring help

pauldunn1971 · Aug 27, 2023

hi could some one please help me with the wires on this light switch please i need to change it to a new one
any help would be apreciated thanks

westward10 · Aug 27, 2023

Are there terminal markings at the switch for the red, yellow and blue wires?
Is there earth wires attached to the back box?

littlespark · Aug 27, 2023

Is there any marking moulded into old switch?

I would think the one switch with red, blue, yellow… put the red into Com, and the yellow/ blue into L1 and L2 of the new switch.

On the other half, one red into Com, other red in L1 or L2… doesn’t matter which.

The new switch is simply 2 separate switches on the same plate.

[ElectriciansForums.net] light switch old wiring help

pauldunn1971 · Aug 27, 2023

westward10 said:
Are there terminal markings at the switch for the red, yellow and blue wires?
Is there earth wires attached to the back box?

hi the only marking are the middle with com and the back box are earthed i did change the one upstairs yesterday wich is a single switch were there was 2 red wires together red and yellow together and the blue on its own if that helps

westward10 · Aug 27, 2023

As with the drawing above.
The red, yellow and blue wires, blue into COM, red into L1 and yellow into L2 (it is odd red isn't into COM on the old one but doesn't matter).
The two reds, one into COM the other L1, doesn't matter which way around.
You also need the earths connecting to the earth terminal on the new switch.

littlespark · Aug 27, 2023

ok, i assumed red was in Com.

Shows how complex even simple light switch connections can get.
At least this one had a 'before' photograph taken.

pauldunn1971 · Aug 27, 2023

westward10 said:
As with the drawing above.
The red, yellow and blue wires, blue into COM, red into L1 and yellow into L2 (it is odd red isn't into COM on the old one but doesn't matter).
The two reds, one into COM the other L1, doesn't matter which way around.
You also need the earths connecting to the earth terminal on the new switch.

thanks very much for taking time out to help it worked a treat much apreciated

westward10 · Aug 27, 2023

littlespark said:
ok, i assumed red was in Com.

Shows how complex even simple light switch connections can get.
At least this one had a 'before' photograph taken.

I was pretty sure the centre was COM but had the blue in whereas most people would use the red.