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Replacing light switches in upstairs bedroom, wiring help needed

Postby Altho83 » Sat Mar 20, 2021 10:32 pm

I’m replacing light switches in my upstairs bedroom. I’ve stupidly removed the old ones without taking photos of the wiring setup.
The bedroom switch has one earth cable, 3 live cables, and 3 neutral cables.
The new switch has an earth port, a com port, an L1 port and an L2 port.
I had a mess around yesterday with various wiring setups and ended up giving myself a really nasty shock!
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Postby stoneyboy » Sun Mar 21, 2021 10:52 pm

Hi altho83
Sorry but on the basis of your photo no one on this forum would be able to tell you where the wires go. If you have an electric meter which measures AC volts and Ohmn resistance we could suggest how you can check the connections. Your alternative is to get in an electrician but be aware that they might not be too happy about the lack of earth connectors in your cables.
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Postby Mr White » Sun Mar 21, 2021 11:17 pm

Altho83. First of all I should point out that just because a wire is black does not mean it is Neutral. Like wise just because a wire is red does not mean it is Live.
If you think about it, if they were all live and neutral, when they are connected via a switch it would go BANG as you would have made a short circuit.

Where lighting circuits are concerned one or some of the blacks could be "switched live" (They go live when the switch is operated)
With that fact in mind, it is actually down to the person who installed it as to what colour does what, and since it was none of us, the only safe option you have is to employ the services of a competent person to ascertain what each cable is for and to reconnect it accordingly.

As for the "missing earth cables" It looks like the earth sleeving has more than one conductor in it (It looks like it has two) But it does not account for the 3rd cable. It may also be an addition as prior to 1966 lighting circuits did not require an earth.
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