Landing lights...

[happysteve]

(... no, not the ones on runways...)

Someone said that in the trainee section "there's no such thing as a stupid question," and so I will test the limits of this hypothesis...

In all the houses I've lived in, where there are two circuits for lights, the landing light (at the top of the stairs, and controlled by switches at both top and bottom of stairs) is always on the downstairs circuit. Why? And is it still done like this in new builds?

I had a couple of thoughts:

1. It's somehow more easier to run the cables from downstairs (switch) to up.
2. The landing light switch at the bottom of the stairs is usually 2 gang, also controlling a light in the hallway. It would be rather silly to have two separate circuits going to the same accessory - for instance, the home owner might isolate the downstairs circuit in order to replace the face plate, not realising that the feed from upstairs is still live.
3. Safety, from a "stumbling about in the dark at the top of the stairs" if the upstairs circuit trips - you've still got one light on up there, at least.
4. It's just always been done that way, and no-one can remember why.

Cheers!

 

[Marvo]

We install out lighting circuits differently where I am but I'll hazard a guess. I think it's because the downstairs hall switch is likely to have multiple levers for porch light etc so if the 2-way hall/stairs/landing light system was supplied from the upstairs light circuit you'd have live wires in that downstairs switch from 2 separate circuits which means there'd be no single point of isolation for that switch assembly at the CU other than the main isolator.

All that said I like you answer number 4, it shows you're wise and cynical beyond your years which is good. It's also very possibly the right answer

Don't take my guess as gospel please, rather wait for a UK based member to either confirm or to educate both of us

 

[telectrix]

the problem lies with the borrowed live scenario, where the N is from upstairs circuit, and the L from downstairs. the conventional way these days is to feed both L and N from the upstairs circuit, and use 3 core strappers to downstairs switch. you then have 2 circuits feeding L into the downstairs switch if its a 2 gang with the hall light, so a better way is to separate the switches .

 

[Marvo]

Thanks Tel. Just out of interest is it legal to install a 2 or 3 lever switch with more than one supply coming from different circuits to the same switch assembly?

I like the 'no such thing as a stupid question' thing, it means us foreigners can also learn something

 

[telectrix]

it complies to regs. marvo, same as we can have more than 1 phase in a switch position.

 

[Silly Sausage]

Up lights and hallway, and Down lights and landing separate ccts, so you'll always have some light if one goes.
Separate ccts, or even phases, within a switch, perfectly acceptable to me; we all know how to check for dead!
Repetition...Just seen Tel's post!

 

[happysteve]

Thanks all for your replies. To summarise:

Tel said nowadays landing lights are on the upstairs circuit, to avoid potentially borrowed neutral.

Archy says he'd put (upstairs) landing on downstairs circuit, and (downstairs) hallway on upstairs circuit, so you've always got some light.

Two separate circuits to same accessory (two gang/lever switch) no problem.

My question stems from weighing up the pros/cons of each design. If you're doing the design from scratch, you can ensure you wouldn't have any borrowed neutrals. It then boils down to the safety aspects. I like Archy's ethos - stumbling around in the dark is no fun. On the other hand, a homeowner might (naively) expect the switch on the "fuse box" that says "upstairs lights" to switch off all the upstairs lights! If you're standing on a wobbly chair at the top of the stairs changing a lamp, the last thing you want is a surprise! But it seems to be such a common thing - on older houses at least - maybe everyone knows about it. But if practices are changing (or have already changed... "the conventional way these days...") then at some point folk are going to be really surprised that one of the upstairs lights is on the downstairs circuit!

Anyway, cheers. I like the fuzzy questions (and answers)