Wiring A Switch

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maclarencat | 08:36 Wed 18th Sep 2019 | Home & Garden
11 Answers
So I did something really stupid. We have just moved house and all the switches are different Some brass some white plastic some black some steel so I decided to make them all white plastic . All was going well as I was swapping* like for like but then I took a switch off in the hall then the phone rang and when I came back I could not remember which wire went where grrrrr stupid I know. The switch has a strange wiring. The back of the switch has common L1 and L2 there are 3 wires coming in . One is red and earth , one is red black and earth and the last is again red and earth. Anyone know how it should be wired?


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It's a two-way switch; the other switch is probably upstairs and the pair of them control the stairs lighting. Wire the switch exactly like its pair. When finished, with both switches in the same position (up OR down) the light should be off; if not reverse L1 and L2 on one of the switches.
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It is a single switch at the bottom of the hall. There is a double switch as you come in . Ne for the outside light one for the light at the bottom of the hall. By the bottom of the hall there is a double switch which operates the light at the bottom of the hall and one at the top of the hall. At the top of the hall is the switch I have disconnected which I think should just operate the light at the top of the hall. So no two are alike!
This might be useful.
The fact that the switch has three terminals means it is a two-way switch; that means it CAN, but does not have to, be one of two switches which control a single light.
You have three wires, two are the same colour and one is different; connect the odd wire to Common and the others to L1 and L2. Now try the switch; with the switch "in-at-the-top" the light should be off (by convention). If the light is on reverse the wires connected to L1 and L2.
Please don't confuse a two-way switch with a double switch. A two-way switch can be used as one of a pair to control a single light. A double switch is simply two switches on a single plate, each one controls a different light. Just to confuse matters you can also have a double two-way switch, which is 2 two-way switches on the same platten.
Just to add to the confusion...

I think bhg may have missed the fact that Mac has FOUR wires, not THREE.
TWO single reds; and one pair (black and red.)

With four connections, I wonder if this is an intermediate switch, ie one for THREE-way light control.
Quite common. Perhaps a light is controlled by a switch at the door; one at the bottom of the stairs; and one at the top of the stairs.

We need to know, if only to rule this out ;o)
So, Mac... does your switch have four holes?

//The back of the switch has common L1 and L2 there are 3 wires coming in.
One is red and earth , one is red black and earth and the last is again red and earth.//
Builder - I must say I found his description of the wires very hard to understand, so I think you're right ie, he has 3 cables coming in each containing more than 1 wire.
Try this..isolate circuit......put the 2 single reds into common.....then from the pair..put red into L1 and black into L2. Then connect earths into lug in back box.
Come on Mac.......don't keep us in the dark!
Question Author
Thank you everyone for your answers . I had to get an electrician to sort it out. It seems the man who lived here before had a unique way of wiring! Oh well all’s well that ends well We now have correctly functioning lights

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