12v RV lights

When the Hot wire leaves the battery bus (typically positive). You install wire heavy enough for the current and acceptable voltage drop.

Assuming the label is correct 12 volts @ 0.15 Watts:

• P=V*I
• I=P/V = 0.15 watts / 12 volts = 0.0125 Amps

That is a very tiny amount of current... You can run almost any insulated wiring you can find... But you should probably stay with 18AWG or heavier--So the wire is not broken by somebody snagging it. Or, use 14 AWG Romex cable--And that will be more than solid and safe.

The minimum fuse you should probably run is 1 amp... If you use 14 AWG, you can go upwards of 15 amps, but if all of your lighting/current is so small--I would stick with around 5 amps or so.

Voltage drop is nothing with that small of current... But a useful example, Say you put 3 amps total load (other lights, small fan, etc.) and want a maximum of 0.5 volts drop on 14 AWG wire--How far could you send it (this drop calculator uses 1 way run, not 2x or round trip length):

http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=8.286&voltage=12&phase=dc&noofconductor=1&distance=33&distanceunit=feet&amperes=3&x=49&y=9

14 AWG @ 33 feet run:
Voltage drop: 0.50
Voltage drop percentage: 4.17%
Voltage at the end: 11.5

So--The maximum I would run a 3 amp circuit on 14 AWG wiring on 12 volts with 1/2 drop would be ~33 feet.

-Bill "more math, less confusion" B.

That small of light (low power LED)--Almost any insulated wiring will work fine for you... Just have a small fuse (1 amp or so, depending on the gauge of the wire) in the positive lead from the battery bank... Then the switch (positive side), and the negative (return lead) from the light back to the battery -bus.

Not trying to over complicate--Just ignore me on the other suggestions--Unless you want to have more devices out there later.

The Black vs White for the LED wiring... Is a bit of a strange one. Black in DC system is negative. Black on AC systems is "Hot" and White is return.

Try to just tap the LED (pick a color) to + and -. If it does not light, reverse the leads.

You can try a volt/ohm meter, set to Ohms (or diode check) and see if you can light the LED (do it in a dark room, will not be much light).

It is hard to guess.. It really depends on the input circuitry (if any other than a resistor). LEDs generally do not like reverse voltage more than 4-5 volts or so--And they can be damaged by more.

Sorry for the complexity,
-Bill