2 way swtching using 2 core and earth

2 Apr 2013
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United Kingdom
Just finished plastering and decorating hall/stairs/landing, decided to change all light switches and ceiling roses, thought it would be straightforward, so started disconnecting upstairs ceiling rose and 2 gang/2 way switch to replace with new (without noting original wiring :oops: ) Unfortunately these were not wired in a conventional manner and I'm now stuck.

In the upstairs switch I have 2 x 2 core and earth cables and in the ceiling rose I have 3 x 2 core and earth cables, one of these cables has the black wire cut off to leave a single core cable. The old switch also had a connection fitted between both commons.

The switch operates the bathroom light and and the landing light.

The other 2 gang/2way switch in the downstairs hallway operates the hall light and the upstairs landing light and has 3 x 2 core and earth cables going into it, one of which also has the black wire cut of. I haven't disconnected this switch, it is wired as follows;

Cable 1 - BLACK to L1 and RED to COM (hall switch)

Cable 2 - RED to L1 and BLACK to L2 (landing switch)

Cable 3 - single RED to COM (landing switch)

Is this enough information to be able to advise me how to rewire upstairs?
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You must learn enough to gain a genuine understanding of how lighting circuits work, and then work it out for yourself. A multimeter will be needed to identify cables, but you should have one of those anyway of you want to do electrical work.

Just blindly following instructions to put-this-wire-in-that-hole without knowing why is an extraordinarily bad idea.
Sounds like you have a borrowed neutral there, so you need to be extremely careful when working on this wiring. Wires that appear to be dead my still be or become live unexpectedly.

You must switch off the main switch for your entire installation before working on this wiring. Isolating the circuit which powers that light will not fully isolate the wiring.
I have a rudimentary understanding of electrical circuits, enough to work safely at the least. What I don't understand is why the single core runs from the bottom switch to the upstairs ceiling rose and not the upstairs switch, and why the upstairs switch has both COMs shorted. This is also why I am unwilling to just go ahead and see what happens if I just stick some wires in some holes.

I tried to find a diagram of this particular wiring, that I could study, and perhaps understand the reasoning behind this, but I couldn't, so I've come on here for advice.

Obviously you have a genuine understanding of how this lighting circuit works ban-all-sheds, so perhaps you can offer me some worthwhile advice on how i can rewire my switch and and ceiling rose,
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Its a 2 way switch.

I think I've worked it out, and if I've worked it out correctly, there's no borrowed neutrals.

However, you must take precautions when working on the circuit to isolate safely, in case I am mistaken!

Have you worked out what the single wires do yet?

What about the pairs at the landing switch?
Got there in the end, thanks.

ceiling rose L-R

1-Landing light - blue
2-Single core from bottom switch - red
4-Bathroom light - red
5-Bathroom switch - COM - red
6-Bathroom light - black
7-Bathroom switch - L1 - black
8-Landing light - brown


Thanks all for pointing me in the right direction

L1-from L1 downstairs - red
L2-from L2 downstairs - black
COM-to bathroom switch COM - red
Thank you all for pointing me in the right direction.

no more sheds, you were right, I was looking for an easy out instead of figureing it out :D
So how it was wired was with the switchwire for the landing coming from the hall light switch fed via strappers fed from the live from the upstairs circuit.

Normally, it is the other way round: the feed is at the hall switch and the single common on the landing switch goes to the landing bulb.

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