Extra Garage Lighting

jellybeard999 · 12 Jan 2019 at 15:58

I've currently got a single LED batten in the garage at the back, and I'm wanting to add another to the front.

Currently, there are two wires coming from the existing light - one to the switch, i presume the other runs back to the consumer unit. 1.5mm2 wire from what I can gather.

To add an extra batten, can i take the wire to the switch, connect this to another batten (ie in series), then wire the new batten to the switch?

If I'm understanding the existing wiring correctly, it is as A in the image below. I'm hoping to add an extra light as in B.

bremen1874 · 12 Jan 2019 at 16:03

I'd wire it in parallel with the existing light.

jellybeard999 · 13 Jan 2019 at 13:40

bremen1874 said:
I'd wire it in parallel with the existing light.

So a wire from switch to each light, then a wire from each all the way back to the consumer unit?

What benefit does this bring? Or is series not suitable?

bremen1874 · 13 Jan 2019 at 13:50

I can't think of any mains wiring that isn't done in parallel.

You can wire the two lights together rather than running multiple cables. Leave the existing wiring as it is and connect a length of T&E between the LNE of the first light and the LNE of the second light.

Mercenary Keyboard Warrior · 13 Jan 2019 at 13:51

I am not sure I believe the second is running to the CU. Normally the cable runs from the Cu to the switch and cuts the live before it gets to the light.
Can you follow the cables a bit more closely and check? Could you have an outside light or something else running off the light? even a socket or something. garage wiring is often "not what it should be"

I would wire it Cu -> switch -> junction box, feed 1 to light 1 and feed 2 to light 2.
Probably easiest to position the junction box by the light you have, move the current feed to the junction box, then add a short cable to existing light, and a new cable of whatever length you need to the new light.

UnworthyBean · 13 Jan 2019 at 13:58

If you wire in series and the first one fails, don't the rest of them not work? Admittedly quite rare with led lights but can happen.

bremen1874 · 13 Jan 2019 at 14:03

Only worth using a junction box if the terminals in the existing light are too small to accept two sets of wires or it makes the makes the wiring layout much easier. Either option will work, so do what suits.

If you're adding the second light in parallel you don't need to worry about how the first is wired.

Mercenary Keyboard Warrior · 13 Jan 2019 at 14:04

UnworthyBean said:
If you wire in series and the first one fails, don't the rest of them not work? Admittedly quite rare with led lights but can happen.

Yeh but in reality you don't because you tend to use the terminals for all wires so you dont get issues with failure

Mercenary Keyboard Warrior · 13 Jan 2019 at 14:08

bremen1874 said:
Only worth using a junction box if the terminals in the existing light are too small to accept two sets of wires or it makes the makes the wiring layout much easier. Either option will work, so do what suits.

If you're adding the second light in parallel you don't need to worry about how the first is wired.

Yeah agree, but they are like 70p so for me its just easier to do as its easier to knock one out if you need to for some reason. Eg if unit 1 fails and your going to need to put a new one. Disconnect power, remove wire from light 1 in junction box, reconnect power, do all the pre work of installing and then disconnect power and wire it in.
Ive seen people trash a light fitting in a garage so for me I just go belt and braces, assuming someone will sooner or later mess up, easy to do with the sorts of things people do and keep in garages.

jellybeard999 · 13 Jan 2019 at 14:31

Mercenary Keyboard Warrior said:
I am not sure I believe the second is running to the CU.

I need to check in more detail.

Thanks for the replies all. I'll come back with more accurate picture.

It's all been recently rewired (year or so ago). I had an up and over door, which has since been replaced with a roller door, so the lighting is all at one end.

paintguy · 13 Jan 2019 at 15:39

bremen1874 said:
You can wire the two lights together rather than running multiple cables. Leave the existing wiring as it is and connect a length of T&E between the LNE of the first light and the LNE of the second light.

I would do this (and have in the past)

Providing you can get an extra set of wires into the terminals of your existing light I see no reason to complicate things by going your option B route. Just piggy back the new light off the existing one.

Adam_151 · 13 Jan 2019 at 18:35

While you could do it as per (B), and there might be good reasons if you were starting from scratch and that fitted your physical layout, you have to note that the link between the two fittings would have to be 3C+earth, you need 3 current carrying cores ((1)You have to send an unswitched live to the switch which is at the far point, (2)you have a switched live comming back from the switch and going to both fittings, and (3) You have a neutral comming from the baord to go to both fittings.

If you already have (A) then as paint guy says its going to be far easier just to come off the existing fitting and wire the new fitting as a 'slave' otherwise you'd be making work for yourself, would have to buyy a drum fo 6243Y, and some brown and blue sleeving.

It is important with such things to understand why you are doing things the way you are, rather than just running cables how you think and randomly trying differnt combinations of cores until it works.....

jellybeard999 · 13 Jan 2019 at 19:27

Adam_151 said:
It is important with such things to understand why you are doing things the way you are, rather than just running cables how you think and randomly trying differnt combinations of cores until it works.....

That's why I'm asking

If I can just wire straight from the other light, that sounds like a good option. I wasn't particularly pushing B, but presumed that would be the standard approach.

I've already got plenty of spare 1.5mm2 t+e

Adam_151 · 13 Jan 2019 at 19:59

jellybeard999 said:
I wasn't particularly pushing B, but presumed that would be the standard approach.

Not normally, normal practice is to take the feed in an the feed out to the next room to the most convientient light (normally the one nearest the door), switch drop from that first light, then slave all the other fittings off the first by running around them in turn.

My loft lights are wired like (B) though, because the cable comes from the CU in the garage upto the furthest fitting in the loft, through all the fittings along the length of the loft, and finishes at the switch near the door, just about all of it is wired in 3C&e, including the cable from the CU, such that a switch live is taken back down and theres a neon indicator near the CU in the garage to remind me if I've left the loft lights on. However if the loft hatch was near to the end where the supply came from, it wouldn't be wired like that

jellybeard999 · 10 Mar 2019 at 15:48

Thanks for all the replies. I've finally got round to doing this today and got 99% of the job done, but wanted to seek confirmation before I wire up the new light. The old wiring is as pictured below, with a neutral connected to the live on what looks to be the wire going to the switch. Both lives are joined together with a terminal block.

I have wired up the new light, ran the wire to the old light as a "slave" and am about to connect the new light to the old as per my MS paint drawn wire.

I will also add some earth sleeve to the bare wire already in place. Not sure if it is necessary, but I think it should probably have some.

bremen1874 · 10 Mar 2019 at 16:04

Your plan looks okay.

In theory, the blue wire that's connected to the live should have a bit of brown sleeving on it to indicate that it's a switched live not a neutral.

The earths should be sleeved.

jellybeard999 · 10 Mar 2019 at 17:02

bremen1874 said:
Your plan looks okay.

In theory, the blue wire that's connected to the live should have a bit of brown sleeving on it to indicate that it's a switched live not a neutral.

The earths should be sleeved.

Thanks. All done and working. I sleeved the earths and properly labelled the switched live.