Light switch wiring

[johnty1]

Looking at a nearly completed extension the other day, I noticed that there were two separate cables awaiting connection in each light switch patress, one being a live feed and the other going to the light fitting. I know how lighting is wired in the style where one cable carries a live feed through the switch back to the junction box then to the lamp, but how is this style wired up? Thinking about it, there seems to be one connection point short using a conventional light switch.

[The Natural Philosopher]

There is.

Common the neutrals using a connector block, and maybe the earths as well, but take a 'tail' from that to earth to the switch metal, and use L1 and common for the two reds (or whatever colour they are these days)

[johnty1]

Thanks. So one has to put a connector block in the back box? How is this better than using junction boxes in the ceiling void, or am I missing something?

[dave stanton]

Because the joint is accesible much more easily than under floorboards.

Dave

[Lobster]

I think just when specific circumstances dictate; eg I'm shortly going to be fitting an outside light; the switch will be almost directly on the other side of the wall from the light's location, and it will be under the stairs which will make it a sod to get cables to. Using junction boxes above the ceiling I'd need to run two cables (would be about 4-5m long); one running to the switch, the other to the light fitting. Far easier to have a single cable running down to the switch, and then another short one through the wall to the light fitting, handling the switching wiring using a connector block behind the light switch.

David

[johnty]

OK, I see. Thanks, all.

[The Natural Philosopher]

Easier to get at when they fall to pieces?