downlights recessed lights question

[ban-all-sheds]

I know technically it would work I was just wondering if there are regs against running 12V fixed wiring around a house? And if there are light switches that can handle the 20 or so amps..

20A wouldn't be enough. Andemz was talking about having 25 x 50W lamps in his kitchen - that's over 100A.

Perhaps this is an area where we might see changes, low voltage lights are everywhere now. Like you say, cabling would be thick and thus expensive and unwieldy.

It would be impossibly thick and expensive and unwieldy - Andemz's example is perhaps a bit extreme, but domestic lighting circuits are normally 6A or 10A. At 12V that would become 120A or 200A. I don't see how you could ever get ELV circuits in houses, except for things like doorbells where someone has fitted the transformer in the CU.

 

[ban-all-sheds]

you could also have one HUMUNGUOUSLY BIG tranformer running all the 12 v lights in your house easy, BUT how big is this transformer to be, and suppose you want "just a few more lights" what do you do then? Not to mention the size of the cable to run all the lights

Stupefyingly big. Somewhere I've got a big w/w ELV lighting transformer which I rescued from an office refurb. From memory it's rated at (only) around 5-600W. It's the size of a shoebox, and is very heavy (think for a minute how thick the wire in the secondary winding has to be to deliver 40-50A). And as for the wires to the lamps, they'd have to be even bigger than you at first think - as voltage drop is proportional to current, not voltage, you get a lot more and yet you can tolerate far less. Whilst losing 2-3V on the run to a 240V lamp would have no visible effect, if you run your 12V halogen at only 9 or 10V the effect on brightness (and colour) will be very noticeable. So not only do your cables have to be extra thick, they all have to be the same length (or at least, all the ones in the same room do) if you want all of your lights to look the same.