Led Driver from mains

[itsallaboutyou]

Evening all. Usual caveat - I will employ someone - but I like to have my head (as best as I can!) around what needs to be done.

I’ve built some custom alcove units at home for the boss and she seems pretty happy with them!

currently, I have a double triac dimmer serving one ceiling light with 5 x 48w halogen G9 bulbs one one switch and two wall lights with 4 (in total) halogen G9 bulbs.

where the wall lights were, I’ve terminated the 3 core and used a wago box (as it’s now in accessible) and extended the 3 core to the top of the unit, again terminated.

From here I’d like to install a 12V, 75W triac dimmable driver and approximately 5m of 4.8W strip (ideally 10m) dimmable with a trailing edge (hopefully buzz free dimmer) but... when I do the maths, although the driver will take up to 48w easily, that’s coming out at some ridiculous amperage. Is my maths crap? I would imagine, as a layperson that I’m misunderstanding the correlation. I confirm again that I’ll get someone in to do it!

this would be repeated in the second alcove.

the dimmer can manage up to 120W - so even if (added together) my drivers can do 150w - is that still remotely possible? I would not be looking to go over 100w in total.

It’s a standard 6A rcd in the consumer unit.

is what I’m proposing doable?

if not, I’ll just use a dimmable batten on the top as an up lighter and purchase one of these kits..

cheers all.
Tom

 

[winston1]

48w on a 240v supply works out at 200mA. Your maths?

150w is 625mA.

 

[itsallaboutyou]

Ha! My maths is out by a factor of 100. Needless to say, having thoroughly redone - it seems to work pretty perfectly.

No idea, apart from being thick.

Is my 48w at 12v not 4A? Surely not? Am I missing a division there or am I being daft and relying too much on a web calculator.

 

[333rocky333]

Ha! My maths is out by a factor of 100. Needless to say, having thoroughly redone - it seems to work pretty perfectly.

No idea, apart from being thick.

Is my 48w at 12v not 4A? Surely not? Am I missing a division there or am I being daft and relying too much on a web calculator.

48w at 240 volt = the input current
48w at 12 volt = the output current

 

[oldbutnotdead]

You've got 4a at 12v (48W) running on the load side of the driver-should be ok for 10m but check the mfr instructions for how many sections you can daisychain before volt drop becomes an issue.
The supply side at 240v needs to deliver 48w so (as above) about 200mA- which may be too puny for triac, again check minimum load and LED suitability on the dimmer specs.

No partcular reason you can't do this yourself as long as any new 240v cabling is RCD protected and in safe zones