Loft lighting

Dewi · 7 Dec 2005

I am carrying out a loft conversion and want to change the existing lighting that I have up in there. Ive currently got a 4 ft fluorescent tube switched from the bottom of the stairs. I want to replace the tube with 4 recessed lights that will all come on together when switched on and also replace the single 1 way switch with a 2 way switch. Can someone tell me if I am likely to overload the circuit as it is only 1mm cabling and what will be the easiest way to do it.

Qedelec · 7 Dec 2005

Without knowing the loading it will be difficult to advise you.
You will need to state where the two way light is to switched from.

Little details like this save us getting out the crystal ball, your help is appreciated,, thank you.

Dewi · 7 Dec 2005

The light is to be switched from both the bottom of the stairs and the top of the stairs. Distance is only about 5 mtrs. Is this what you mean?

Steve · 7 Dec 2005

Dewi said:
The light is to be switched from both the bottom of the stairs and the top of the stairs. Distance is only about 5 mtrs. Is this what you mean?

no. Add up the total light wattages on the lighting circuit in question. If you have a 6 amp protective device, you can have up to 1380w of lights on one circuit. For 5amps, the limit is 1150. Of course, in practise you may not ever have all the lights on at once, but exceed these limits at your risk.

Have you told building control about this loft conversion?

Dewi · 7 Dec 2005

The wattage is approx 600W on the upstairs lighting circuit. I would expect to add an extra 100W approx, so should be ok. I was thinking of changing my existing 1 way switch on the 1st floor landing with a 2 way - but how do I get another 'constant feed' wire down through the trunking in the wall to the switch?

Steve · 7 Dec 2005

Dewi said:
The wattage is approx 600W on the upstairs lighting circuit. I would expect to add an extra 100W approx, so should be ok. I was thinking of changing my existing 1 way switch on the 1st floor landing with a 2 way - but how do I get another 'constant feed' wire down through the trunking in the wall to the switch?

do you fully understand how 2-way switching works? see for reference, it is explained in glorious technicolor detail there.

Dewi · 8 Dec 2005

I do understand how 2 way switching works actually but I've never installed one before. Basically I'm looking to replace the current 1 way switch with a new 2 way switch at the bottom of the stairs (trying to utilise the existing wiring within the trunking in the wall so that I don't have to chase out the wall to run another cable - hence my question about the constant live wire) and then fit a new 2 way switch at the top of the stairs. I appreciate it is difficult to communicate the finer details on a forum session such as this.

ban-all-sheds · 8 Dec 2005

Dewi said:
I do understand how 2 way switching works actually but I've never installed one before.

But if you understand how it works then you understand how it works.

Even if "how do I get another 'constant feed' wire down through the trunking in the wall to the switch" makes me wonder if you do understand it. Maybe I don't understand what you mean by constant feed wire.

Basically I'm looking to replace the current 1 way switch with a new 2 way switch at the bottom of the stairs (trying to utilise the existing wiring within the trunking in the wall so that I don't have to chase out the wall to run another cable - hence my question about the constant live wire) and then fit a new 2 way switch at the top of the stairs.

As you know, there are several different ways of wiring a 2-way switching circuit.

And as you also know, they all involve a cable running between the two switches.

And as you also know, you cannot therefore add another switch without adding a cable of some sort to the existing switch

Steve · 8 Dec 2005

i think what ban means is he doubts your real knowledge of this job.

Do look at the for reference section, all the answers are there - you may even find an easier way to do it.

slippyr4 · 9 Dec 2005

how do I get another 'constant feed' wire down through the trunking in the wall to the switch

Wrong terminology, but you've decided you need three live conductors in the switch but currently only have two.

Now, you said the cable is in trunking. If so, it's quite likely you could just pull a new 3core+Earth cable through.

You probably ought to do that anyway. With two-way lighting, the switch cable from the downstairs switch needs to run to your upstairs switch, not your light fitting. The exisiting one probably doesn't reach.

However, IF the downstairs switch is a two-gang and also switches another light, and IF that other light is NOT two way switched, and IF that light is on the same circuit as the loft light, then you could run a wire from the other lights phase terminal (in the switch) across to the landing switch common. Then use your existing cable for the L1 & L2 connections.

If that doesn't make sense, then you shouldn't be doing it.

Dewi · 9 Dec 2005

Thanks slippry4. I think you understand me better than I do !. You've answered my question very well and it has now all clicked into place. Thanks for your advice everyone.

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Loft lighting

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