Wiring in a lightswitch

[romeogolf]

This is my bedroom light switch, with two red wires into one end and a single red wire in the other. Yes, it was upside down on the wall.




I want to replace it with the one below and had, naively, assumed that the backs of each would be the same and I can do a straight swap.



Could someone tell me which wires go where and/or provide a brief crash-course in Electrics 101 for the sorts of simple jobs you're not taught how to do at school, but probably don't require a professional?

[mdw]

Wll worth buying for the simple stuff.

[RizzoTheRat]

First off, get a multimeter or one of those light up screwdrivers that can test which wire is live.

Your current switch probably has the 2 joined wires as a live feed and the other one feeding that live to another switch somewhere. The other one is probably a switched live, as in it's only live when you flip the switch, and goes to the bulb, which will then connect to a neutral. Of course it could be the other way round with one live and 2 switched lives going to 2 different bulbs. Switched live is usually a different colour or has a little collar round it to identify it as such.

"Probably" is a doing a lot of heavy lifting there, always check before you touch!

Your new switch is a 2 way, so it will connect common to L1 when flipped one way, and L2 when flipped the other, so you you only need to connect Common and L1 and leave L2 disconnected.


ETA:

Black (neutral) and Red (live) is the old UK colours, new stuff is supposed to be Blue (neutral) and Brown (live) so you'll see different colour combinations if you're looking at at how to guides/pictures

Edited by RizzoTheRat on Monday 10th February 13:12

[miniman]

So it makes no odds which is live.

Pair of wires to L1 single wire to COM (which is how it is in the existing switch if you look carefully)

Edited by miniman on Monday 10th February 13:15

[geeks]

miniman said:

So it makes no odds which is live.

Pair of wires to L1 single wire to COM (which is how it is in the existing switch if you look carefully)

Edited by miniman on Monday 10th February 13:15

Yup this, the current switch even has Common written next to the common terminal

[romeogolf]

geeks said:

miniman said:

So it makes no odds which is live.

Pair of wires to L1 single wire to COM (which is how it is in the existing switch if you look carefully)

Edited by miniman on Monday 10th February 13:15

Yup this, the current switch even has Common written next to the common terminal

I'm mostly shocked at how terrible my eyesight must be that I didn't see this. If I'd seen it yesterday afternoon I'd have been able to answer my own blimmin question! Thank you!

[Mr Pointy]

Although it makes no difference in this case the pair of red wires should go to the COM terminal & the single red to either L1or L2 depending on which way up you want the switch to be when it's on. The blacks go into Loop N but can be left in the choc block.

[RizzoTheRat]

miniman said:

So it makes no odds which is live.

Pair of wires to L1 single wire to COM (which is how it is in the existing switch if you look carefully)

Edited by miniman on Monday 10th February 13:15

Yeah, fair point. personally I like to know which wire's doing what though as I'm using smart switches so need the permanent live on the right side.

[netherfield]

https://www.screwfix.com/p/lap-non-contact-voltage...

Cheap enough to buy, this will tell you which is the live wire. Don't buy a neon screwdriver they are crap.

[Belle427]

Just guessing but normally the pair of reds I would expect to be the feeds and in the common terminal.

[megaphone]

Looks like that new switch is metal, it needs to be earthed to be 'safe'. I can't see any earth in your cabling, so you shouldn't use metal fittings on the light circuit. Stick with plastic to be safe and 'legal'.

Edited by megaphone on Tuesday 11th February 08:50

[Baldchap]

netherfield said:

https://www.screwfix.com/p/lap-non-contact-voltage...

Cheap enough to buy, this will tell you which is the live wire. Don't buy a neon screwdriver they are crap.

I'd be very, very careful trusting one of those. Use a multimeter.

That exact detector from Screwfix showed my left knee and hip to be live (honestly!) but a live ring main not to be.

I would not trust one of those at all where mains voltage is concerned. There's even a sleazy disclaimer in the instructions saying they don't work and you should use a multimeter.