I was thinking about getting some off road lights but I had some questions I wanted to clear up before I bought anything. I understand the basic wiring diagram but not to sure about the details. My first question is how do I determine what gauge wire I need to run to certain things. I also would like to know what size fuses and relay I need. I have heard some people say you have to run the negative off your lights to the battery negative but I have heard other people say you just need to ground them. So I'm not sure what to do there. I'm thinking about getting 2 100w or 130w lights. Any help would be nice. Thanks Mike

 

on my 2 kc lights which are 130w. im running 10 gauge wire with 30 amp relay and fuse... and i grounded to the chasis of the truck... and no problems what so ever

 

haha now that i think of it with my other 2 lights that 100 watts im running 12 gauge wire with a 30 amp relay and 20 amp fuse... but i suggest doing it the first way... lol

 

So you ran 10 gauge all the way around? I was thinking you could use smaller wire in different areas. ie switch to power source or switch to ground. But thanks for the info.

 

I found this chart on some website. I tried to just post the chart but couldn't figure out how.

http://www.offroaders.com/tech/12-vo...gauge-amps.htm

If you are running 260 watts (2x130w) then that is 21.7 amps (260w divided by 12v = 21.7amps) plus any resistance in any of your connections.

The relay control side (power from switch-to relay-to ground) should pull very little amperage(less than an amp? hopefully somebody will chime in on this), but I would still fuse it with the smallest fuse you can get by with.
On the relay power side (power from battery-to relay-to lights-to ground) will pull probably 18-24 amps. I would try using a 20a fuse then move up to a 25 if you need too, maybe even up to a 30.
The wire should be measured from the battery to positive side of the last bulb in the circuit. This will give you the length you need for this chart.

I just found this chart online, I'm not sure how accurate it is, but hopefully it will help give some idea of what you're looking for.

Oh yeah, grounding anywhere on the chassis should give you a good ground as long as it is cleaned up first (so you get some metal to metal action).

 

haha sorry i for got that part.. i used 14 guage to use as a signal wire for the relay. and 10 gauge for ground. and put a fuse between the lights and relay