12v light switch / light wiring

[hannaloulou111]

I think I have confused myself, and before I close the ceiling up, I need to have clarification...
I gutted my travel trailer, and I am down to bare metal, I took pics and documented as much as I could, but a yr later, (had to wait for the snow to melt) I am second guessing myself. I move the light switch, and now it raised a question mark.
My light switch has black running to it, and the light has black and two white.
So, what is the correct way to run wiring for my lights?
Obviously, if it running straight to the light that has a switch built in, black and white.
So, not being electrically inclined, and based on all of the wiring in the trailer. (black and white) Another light that has a switch also has one black and two white, so what is neg and positive?... I will go with black and white.
But, in the case of putting a switch in, I run black to switch and white to light. then run black from switch to light? But where does that second white come from?



What are the basic requirements for wiring?

[newman_fulltime]

Whatever color wire is to the fuse panel is the hot w I re

[westend]

The jacket color of the wires is secondary as to their purpose. You need to understand what you're trying to accomplish--sending power that is switched to a light fixture and supplying a ground at the fixture so the electrical path is completed back to the source of power. In our case that would be the battery (or through a fused distribution panel to the battery).

Conventionally, white wires are for (-) phase and black is for (+) phase. You only need to switch the black wire to interrupt power to the fixture. A bulb requires a full path to the source of power, hence both (-), (+) phases are present at the light fixture.

[ScottG]

2oldman wrote:
Sorry, I only fix pictures once per thread.

I know and we don't pay you enough :B

[2oldman]

Sorry, I only fix pictures once per thread.

[hannaloulou111]

ok here is another example.
Two lights, I know both are controlled by a switch.

one light under dinette... First picture.
Has two black pig tailed. Two white pigtailed.



Second light has one black and two white.



The switch controls the outdoor light and the two lights.


I am going to try to map it and update the thread...
But, I am assuming as you stated, that those two lights are on the same circuit controlled by the same light.

[Chris_Bryant]

Yeah- they are running a common white ground, with separate hots for the lights.

[12thgenusa]

The convention in 12 volt RV wiring is black + and white -. The + is switched and the - are daisy chained together and connected to a chassis ground somewhere.

[Tequila]

From what I can see the white is 12v, it is looped to other fixtures. The black wire on the switch is probably switching ground. Its hard to say, could be the other way around, you need to check it with a meter. Easy to run one between the ground of that electrical fitting and the black on the switch. If you have 12 v then the black is hot. If the switch is sending a ground up, they may have even tapped that electrical outlet for it.

[wing_zealot]

Is this 120 volt or 12 volt light? Is the white or is the black the hot wire?

[lanerd]

It's my guess that the white is hot and the 2nd white is running to another light that also comes on with that switch. But that's just my guess.

Your best bet would be to ohm it out and see which one goes to ground.

good luck

Ron

[2oldman]