Wiring 2 Gang Light switch

[bosso20640]

I have a 2 gang light switch which operates a porch light and hall light. Recently I had to disconnect it and though i thought I'd taken care to notice what went where when I got the replacement switch all my careful planning kind of went wrong!!!

So here I am trying to put the correct wires where they should go.....

I have two grey cables entering the back box, one of these contains 3 wires, RED, EARTH and BLACK. The other grey cable contains four wires: RED, YELLOW,EARTH and BLUE. The BLUE and BLACK(From 1st Grey cable) are joined together in a connector block and hang inside the back box. All the EARTHS are gathered together and connected to the back box. That leaves a RED (From 1st grey cable) and RED and YELLOW from the 2nd grey cable. Can anyone please advise where these should go ie L1,L2 and COM.(I did remember the COM did have a extra RED wire looped across.

 

[ban-all-sheds]

1) Does either light have 2-way switching?

2) Do you have a basic understanding of how lighting circuits are wired? //www.diynot.com/wiki/electrics:lighting

3) Do you have a multimeter?

 

[bosso20640]

I have an idea how the lighting works. No it isn't a two way switch. I gather the RED from the first grey wire is the LIVE feed and should be connected to COM (on the first switch?). No I don't have a multi meter, sorry....

 

[sparkyspike]

It sounds like the red (from the red & black cable) needs to go into COM of one switch. Link this with the COM of the other switch with the link wire you will have.

Then wire the other red into L1 of one switch and the yellow into L1 of the other switch.

You will then have all terminals filled, other than the two L2s. COM of one switch will have two wires in it.

This is the usual way. If it doesn't work, then it's time to get a multimeter.

 

[ban-all-sheds]

So you're suggesting a 2-gang switch, 2 cables, 2 lights, but the permanent live comes in on one cable and 2 switched lives go out on 2 cores of the other cable to 2 different lights?

Far more likely, IMHO, is that the permanent live comes in on one core of the 3C+E, switched returns on the other, for the hall light, and the twin&earth cable goes to the porch light.

What probably happened was that someone wanted to add the porch light, so the original T/E switch cable for the hall light was replaced with 3C+E so that a neutral could be supplied to the porch.

bosso - try the red from the 3C+E into a COM, which should be linked to the other COM, and then the yellow into the L1 for the switch you want for the hall, and the red from the T&E to the other L1.

Is it a metal switch faceplate, BTW?

 

[bosso20640]

Thanks Sparkyspike!

I've done exactly as you said. The Porch light comes on but not the hallway light?
I'll have to call up the services of a mate with a multi meter, thanks for your help thus far

 

[ban-all-sheds]

The Porch light comes on but not the hallway light?

Try my idea now...

 

[sparkyspike]

So you're suggesting a 2-gang switch, 2 cables, 2 lights, but the permanent live comes in on one cable and 2 switched lives go out on 2 cores of the other cable to 2 different lights?

Yes, that's exactly what I was suggesting. I was working on the basis that the OP thought the live came in on the two-core! Didn't work though. Hopefully your way will work now!

 

[bosso20640]

ban-all-sheds,

I've done what you suggested too and got the same result. The porch light on but not the hall light? I'm starting to think the light might be U/s?

 

[bosso20640]

ban-all-sheds,

I've done what you suggested too and got the same result. The porch light on but not the hall light? I'm starting to think the light might be U/s?

Same result as I got when I wired the way described by Sparky!

 

[sparkyspike]

Can you get both lights to come on if you try both switches in all positions?

Did you remember to fit the link between the two commons?

Are you sure that you are reading the back of the switches correctly? Don't read left to right, top to bottom, but in triangles - COM at one end and L1/L2 at the other.

Was there a problem which prompted you to remove the switch?

Can't think of anything else right now, other than a faulty light/lamp.

 

[bosso20640]

Yes, reading the back of the switches correctly, it's quite clear. I've not been able to get the hall light on at all no matter what combination I've been putting the wires in. The reason why I took the switch cover off in the first place was because the light kept "tripping" and the switch seemed to be a bit awkward/sticky and therefore I thought that was the source of the problem, seems likely it's not now eh?

 

[bosso20640]

..Got the link in the COM too!

 

[ban-all-sheds]

As a diagnosis step, put both reds and the yellow into the same switch terminal (any one of the 6 - it doesn't matter).

Then turn the power on and see which light(s) come on.

 

[bosso20640]

....just the Porch light, guess I'll have to look at the Hall light a little closer