Replace Plastic 2 Gang Switch With Stainless Steel


Postby boefie1976 » Mon Aug 07, 2017 7:52 pm

I did not take a photo ofvthe old plastic switch but have the normal 2 cables coming into the back box, both have a red, black and yellow/green wire. I need to wire this downstairs switch which vobttols the hallway light downstairs and the light upstairs. All examples of how to wire the switch have more wires. How do I wire the seitvh with the 4 wires, know what to fo eith the earth wires, given the switch has 2 COM, 2 L1's and 2 L2's
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Postby Mr White » Mon Aug 07, 2017 9:54 pm

Sadly there is not such a rule / regulation that says which wire goes where. It also sounds like you are a wire missing (Blue) all anyone can do is guess, but I think a clear picture would help.

Picture of the wires, not the switch.

Incidentally, the switch you have is two switches on the same front plate. So treat it as such. (One switch has Com, L1 and L2, and the other switch also has Com L1 and L2)
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Postby ericmark » Mon Aug 07, 2017 10:01 pm

I have done same myself, with all the other forums you can read the post after posting and correct, but not with this one, so please try again proof reading before you hit the submit button, as I can't work out what you are trying to say.
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Postby kbrownie » Tue Aug 08, 2017 9:25 am

Do you have safe means of testing for voltage and continuity?
As you need to identify which cable is the permanent live and which cables
are serving which set of lights.
I assume the only two way function is on the landing lights?

There are a number of different ways to wire up two way circuits, you need a perm live which will likely be on the switch cable of the hallway light, then the other cable of that set of twin & earth, will be the hallway switch line.

The perm live of the first cables will be linked between both gangs at the common terminal.
It is common that the red cores are used as perm live, but do not rule out the black being it, as we cannot be sure what the installer was thinking when they originally installed.

You will then have the second set of twin and earth cables, that lead to the landing light. It would be wise to look at the landing light switch set up, then replicate where the conductors go to on that switch, with regards to L1 and L2. This may need to be tested via continuity or it will be guess work.
You say you have a neutral terminal on the switch, if this is true? It does sound like you have no neutrals at the switch, so this terminal can be ignored.

A picture of your old and new switch, plus the cables could be helpful.

You have a metallic switch plate, so before you do anything you must verify that the earth is actually connected back to the supply earth and the switch plate must be directly connected to this. If you cannot verify a fault path to earth, then you must not connect metallic fittings.
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Postby boefie1976 » Tue Aug 08, 2017 2:47 pm

Apologies for the spelling, tablet too small.

Can confirm the two reds are live not the two blacks. The first two images are the downstairs hall 2 gang switch and the third image is the upstairs 1 gang hallway light switch.

When I took the old plastic switch off a small wire if I recall was connecting the two Comms...
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Postby kbrownie » Tue Aug 08, 2017 4:09 pm

Are you sure you have two red cores that are permanently live?
Have these been tested when not connected together? As the missing link, would be the thing that makes them both live.
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Postby boefie1976 » Tue Aug 08, 2017 4:29 pm

No my error of having them too close together when testing. Only the red wire on the left is live
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Postby kbrownie » Tue Aug 08, 2017 6:38 pm

So you are testing with a non-contact pen? I would not really trust one myself.

Please confirm by left, do you mean the red that is part of the set, that has the black with the yellow sleeve on.

If so this a little confusing as the landing switch seems to suggest they match up. Do you have a proper test meter, that can test voltage and continuity, this would be a two pole/probe tester.
As we need to identify which are the cables associated to two way switching.
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Postby boefie1976 » Tue Aug 08, 2017 6:58 pm

Yes left is associated with the black with the tape on. I am using a Schneider Voltage tester IMT23009
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Postby kbrownie » Tue Aug 08, 2017 7:35 pm

Yes, just a non-contact pen. Really it best to test with double pole tester. It would give a truer reading.

OK, lets try this.
Red that is perm live to com of one of the gangs, then put the black with yellow tape/sleeve into L1 of same gang and see if this works your hallway light.

Leave other cables disconnected but put them in separate connectors, just to be safe.

If that is success, then you can link across with red link to com of second gang, then copy L1 and L2 with spare red and black in second gang.

Do not forget to safely isolate and connect the earths, but you do need to confirm the earth path a non-contact pen will not do that. You need a two pole instrument, without this you could be putting yourself and other house residents at risk.
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Postby boefie1976 » Wed Aug 09, 2017 6:53 pm

Worked perfectly, mush appreciated Thank you.
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