3 way lighting question

[SJRSJR]

Hi. A question on landing lights.

I have a three storey house with one light on the middle floor controlled by 3 switches on ground, middle and top floors. I've currently got the floorboards up in the top floor bedroom and there's access to the landing light below so I'm wondering whether to get an electrician in to add a second light on the top floor. Would he just be running a cable from the light on the middle floor to the second light or is it more complicated than that? I'm less inclined to get it done if it means running cable to the switches as I don't want the plaster disturbing on the landing. I'm okay with both lights being on/off at the same time as it's only to have a bit more light in the stairwell. Thanks.

 

[PBC_1966]

There are different ways the light could be added depending upon the way the existing setup is wired, but certainly if there's easy access to run a cable from an existing light to the new position and you're happy for both lights to go on and off together, then that's possible.

 

[SJRSJR]

Thanks for that. As the floor is up and the skirting is off he could run the cable from the existing light up an alcove in the bedroom and into the loft above the stairwell. There is lighting in the loft but annoyingly the top landing switch comes up the wall from below rather than down from the loft so I'm guessing that way he'd have to channel up the plaster to connect to it.

 

[Taylortwocities]

Would he just be running a cable from the light on the middle floor to the second light or is it more complicated than that?

Basically that is all that is needed.
Clever, experienced electricians can often find a less disruptive route for cables. Ask him, he can see the site and make some suggestions.
Often there's a boxed in section that has a the soil pipe vent in it…. for example.

 

[SJRSJR]

Thanks. It'd be good if it could be concealed - is it difficult to drop cable behind a lath and plaster wall? But if it does have to go on the surface at least it could go in an alcove and be out of the way.

 

[Taylortwocities]

Lath & plaster walls are largely hollow. Big verticals with laths across. Like this:

so it should be easy to drop a cable from ceiling to skirting level without hacking the wall about.
You'll always have an issue at floor and ceiling level as there will be a decent chunk of timber to drill through.

 

[SJRSJR]

Thanks, that's helpful.

I had a look at the existing ceiling rose. It's only got the live and neutral of the lampholder and the live/neutral/earth of the power supply. How does he connect another cable when both terminals for the live are used? What is the loop for?

 

[PBC_1966]

It's only got the live and neutral of the lampholder and the live/neutral/earth of the power supply. How does he connect another cable when there's only two terminals for the live/neutral?

The terminals in a ceiling rose will usually accept two conductors.

What is the loop for?

The separate terminal block normally consisting of three terminals in the middle? It's used where power is brought into the ceiling rose and then continues on to another light, with a third cable going from there to the switch,

 

[Taylortwocities]

What is the loop for?

http://www.diynot.com/wiki/Electrics:Lighting-Circuit-layouts