I'm working on a project where I want to mount an LED Light bar to the side of my house. The light bar will be closer to the peak of the roof, and the power supply ideally would be in the basement so all I'd have to do is flick a switch.
I'd like to run a wire down my wall, into the basement. I have an electrician friend that can help me with that part, but I'd like to know is if I can run a DC line that far (approx 30-40 feet)? And can I use Romex wire to do it, or would it have to be something else?
Here is my house with a very crude representation of what I'm trying to accomplish:
Here is the light bar I'd like to use:
And here is the power supply that would be mounted to the wall in the basement:
Best Answer
At 25A (300W @ 12V), the wiring is going to have to be fairly hefty.
Since the power supply does not have remote sensing, you'll just have to manually crank it up to compensate for the voltage drop in the wiring.
According to the datasheet, it can be set up to 13.2 V, which gives you 1.2 V of "headroom" for the wiring.
1.2V/25A = 48 mΩ total resistance.
2 strands of 40' = 80' total wire, so the wire can have a maximum of 48 mΩ/80' = 0.6 mΩ/ft of resistance.
Using copper wire, you'd have to use AWG8 to get to this level and deliver 12V to the fixture.