Recessed 12v Lighting - Transformer

Question

I have wired an RV with 12avg romex. Incoming shore power is 110v, to a distribution panel/box.

The lights that I want to use are recessed 12v lights, and the only ones I can find seem to have a transformer built into the line before the actual light, (I can't find any 110v lights that are small enough). I have wired the lights in series.

In total there are 9 lights on 3 switches.

Is it possible instead of using a transformer on each light, to have a larger 110v to 12v transformer on the main source wiring coming from the circuit panel, and this make the whole circuit 12v?

This might be a basic question, so apologies if it is, but also open to other ways of doing it. I just don't want to have to take the walls down and re-wire.

Thanks in advance.

Answer 1

Yes, it would work. Just remember that 12v systems will consume more current than a 110v system of the same power (watts). This means that cables need to be thicker.

The advantage is it would be safer in terms of electric shocks. Also, at least in the UK, wiring regulations for mains is even tougher than for domestic installations, and legally only an electrician can make modifications. Although, precautions still need to be taken since the 12v system would still be capable of causing fires, so good automotive wiring practices should be followed (including using appropriate automotive cabling, sheathing, connections, and so on).

Does that answer your question?

Answer 2

Hmm, there's no other loads than the lights, right?

How about installing an extra 12 volt (small) battery for the lights and run the wires from there? Then add a battery charger from the shore power to the battery. If you use LED lights, then you should be ok. But is you use other kinds of lights, you may run into trouble with voltage drop as the current starts to become large.

For example, if you have 20 watt lamps, then your total current when all the lights are on will be like this: 9 x 20 => 180 watts, that divided by 12 volts will be 15 amps. At that current, with 12AVG wire, you'd lose a volt per 40 feet of wire. Plus your battery will drain real fast.

If you use 1 watt 12 volt leds, your total power will be 9 watts and you should be ok even with a small battery and battery charger.