How can I add a new light and switch to an existing circuit?

Adam · 10 Nov 2020 at 10:54

I'm about to start work on a dining room and will be converting the single light in the center of the room to 4x LED spotlights in each corner of the room. This is straight forward and I'll be having the ceiling skimmed after I cut out channels for running the cables and patch up the center hole which is no longer required.

I have also bought a 5 light pendant (LINK) which will sit above the table. This isn't really going to be the main source of light but more of a feature.

Again I'll be confident adding this light to the existing circuit but this would rely on the pendant light being on when the spotlights are on. It occurred to me that it might be nice to operate the pendant light independantly.

In the dining room there are 2 switches controlling the lights. For ease, I wouldn't mind if just the one closest to the table was connected to the pendant light and I therefore had a 2 gang light switch. I presume I'll need to cut in to the plasterboard so I can run the new switch cable. That's not a big deal as the plasterer will tidy it up when he does the ceiling.

Has anyone done this before? How would I connect this up?

fiacha · 10 Nov 2020 at 11:17

First you'll need to take all the switch face plates / ceiling rose off to see how the lighting circuit has been wired. Once you understand that you can decide on the best way to modify it. This site has all the information you'll need http://www.lightwiring.co.uk .

As always, if you are anyway unsure of what you are doing, get a qualified electrician in to do it.

200sols · 10 Nov 2020 at 12:39

You need to ensure new lighting additions are RCD protected as well now.

lewism · 12 Nov 2020 at 21:53

fiacha said:
First you'll need to take all the switch face plates / ceiling rose off to see how the lighting circuit has been wired. Once you understand that you can decide on the best way to modify it. This site has all the information you'll need http://www.lightwiring.co.uk .

As always, if you are anyway unsure of what you are doing, get a qualified electrician in to do it.

Those are horrible wiring schematics on that website. Anyone coming across this thread please do not use them. They show function rather than how it is actually wired and you'll just get confused if you don't know what you're doing.

checjb · 12 Nov 2020 at 22:11

You'd need to take a permanent live, neutral and earth to the new light and then run a twin and earth cable down to your new switch. That provides the switch live (usually using the neutral wire but identified as line using brown sleeving) to your new light.
Alternatively, you could run the permanent live etc to your new light and use a kinetic switch. That removes the need for writing to your new switch. They're more expensive though.
If you have ANY concerns get a sparky in though.
And get it RCD protected if it's not already.

Adam · 13 Nov 2020 at 13:36

Thanks everyone, rather than have a go myself I have found a few electrical jobs to justify getting someone in.

200sols · 13 Nov 2020 at 14:00

Its a good idea to run neutral down to the switches now as well, many smart switches need it.

fiacha · 13 Nov 2020 at 14:42

lewism said:
Those are horrible wiring schematics on that website. Anyone coming across this thread please do not use them. They show function rather than how it is actually wired and you'll just get confused if you don't know what you're doing.

Not sure which diagrams you are referring to. Link as an example. Fig 1 shows the circuit schematic, Fig 2 shows how it's wired (including cable colour, switch terminals etc)
http://www.lightwiring.co.uk/two-way-switching-3-wire-system-new-harmonised-cable-colours/

If you can't follow those diagrams then you shouldn't be messing with the wiring in your house.

200sols · 13 Nov 2020 at 15:19

fiacha said:
Not sure which diagrams you are referring to. Link as an example. Fig 1 shows the circuit schematic, Fig 2 shows how it's wired (including cable colour, switch terminals etc)
http://www.lightwiring.co.uk/two-way-switching-3-wire-system-new-harmonised-cable-colours/

If you can't follow those diagrams then you shouldn't be messing with the wiring in your house.

They look good enough to me.

pp111 · 15 Nov 2020 at 12:38

Adam said:
I'm about to start work on a dining room and will be converting the single light in the center of the room to 4x LED spotlights in each corner of the room. This is straight forward and I'll be having the ceiling skimmed after I cut out channels for running the cables and patch up the center hole which is no longer required.

I have also bought a 5 light pendant (LINK) which will sit above the table. This isn't really going to be the main source of light but more of a feature.

Again I'll be confident adding this light to the existing circuit but this would rely on the pendant light being on when the spotlights are on. It occurred to me that it might be nice to operate the pendant light independantly.

In the dining room there are 2 switches controlling the lights. For ease, I wouldn't mind if just the one closest to the table was connected to the pendant light and I therefore had a 2 gang light switch. I presume I'll need to cut in to the plasterboard so I can run the new switch cable. That's not a big deal as the plasterer will tidy it up when he does the ceiling.

Has anyone done this before? How would I connect this up?

Just an observation here really, I find it is actually better to wire everything in to the main light, and you can just literally run an additional cable off the light rose, because lights that are independently switched, no one ever uses them unless they switched in the same place as the main light. For example, fitting lighting under cabinets, it's far better to just have them wired in to the main light than having some obscure switch someplace.