I'm adding offroad lights to my front bumper and have a question about wiring them up. I wired lights up on my Yj and Tj but can't remember exactly how I did it. I've installed the switch and relay and ran power from battery to both. I installed the lights and ran a wire from relay to them. My question come with grounding. I grounded the relay to a bolt connected to the body near the fuse box, wired the ground on the switch to a bolt behind the dash panel. I have read to ground the lights to the bolts that hold the lights in place but I have also read to run all grounds to the negative terminal on the battery. Please advise.

 

This should help.

 

Thanks for the diagram. In this diagram, the grounds are grounded to the vehicle, not the negative terminal on the battery. I will connect everything and give it a shot.

 

6 or a half dozen; it's easier to ground to the frame and, if your grounds are clean, yields the same result.

 

I'm not sure what 300w of lights will cost you... but you may want to have a look at some HIDs.

 

300W and a 25 amp fuse??? I'm not sure if that'll work, when I put my KC's on with 130w they gave me a 40amp relay.

 

I would want the switch to be rated higher than the fuse. If they are both rated the same, then either one could act as the fuse and get fried.
The fuse should be the weakest link, so it will for sure be the place to fail.

 

I wouldn't recomend applying that kind of a load to a switch. Even if it is rated. They tend to get hot. Best to use a relay.
Your calculation is correct. I asume that you are refering to two 150 watt lamps?. Use #10 awg for power from the battery. You can use a 30 amp fuse. Use #14 awg to each light seperatly. You could use one #10 awg. But bigger wire is harder to work with

 

just go right to a 100amp wafer fuse and call it a day!

 

hope I'm not to late . heres a link to a calculator http://www.crownaudio.com/apps_htm/d...s/ohms-law.htm