Underbody lights....

[thermal]

Dude, there should only be 2 wires on any lighting:
1) mount the light anywhere you want to
2) ground it (black wire)
3) power wire to the positive side of the battery.

I recomment to use at least a 10 gauge wire. Once you run a wire on one lighting, you can tap the rest to it unless you want a separate switch for each individual light........... very simple.