Im wiring up the 4 lights that are on my roofrack and just kinda ran into some questions and need some answers. First off, yes i have searched but this stuff is just kinda like common sense stuff. Since im not really good at descibing, take a look at the two pictures. One is before like it should be, and the second is the way i wanna know if i can wire it up. Take note of the way the two wires from the lights to the relay are now combined. I wanted to know if i could do it this way to try and save from having to run all that extra wire. Besides, it already looks tacky enough running them through the door so the less wires the better. Also, can i ground the lights directly to the roof rack. I read somewhere that it would be fine to do this but you need to also ground the rack to the truck. How would you do this. Anyone got any advice for me. Sorry for the big pictures, Photobucket has got all new and updated and its confusing. ALL the wires that im using are ALLL 14 Guage, keep that in mind.

THIS IS THE WAY THAT IT SHOULD BE


THIS IS WHAT I WANT TO DO, WOULD THIS BE OKAY?

 

My personal rule of thumb is double your rating on devices like relays, switches, etc. If you have two 100w lamps on a 20A relay, you are already at its max rating, have a spare handy. Get a relay rated for double your load, you'll not have to replace it. 14guage will work ok for your runs, but when you're pulling that much power at such a low voltage, fatter is better, resulting in brighter. Lower # is better (10g). If you want to ground to your rack, just make sure you have good metal-to-metal contact where its bolted to the truck, sand it shiny, put some silicone (grease) on it and put it together, bolt tight. OR, make a jumper from some heavy wire, with lugs at each end, and get your ground from the truck to the rack that way, like the ground jumpers on your engine.

 

The two relays that im using are 30 Amp, not 20 amp like in the picture. So it will work the way in the second picture right? The wire wont melt or anything will it? Ground from the truck sounds easy enough. thanks for the adivce.

 

The only differance is that you are putting more current through the 10 amp wire becasue you are sharing it. You will be drawing 16.6 amps through that one line so 10 amp wire will get hot and could catch on fire. If you do it that way you will need heavy wire to the first light and then you can use lighter wire to the second as each ligh draws 8.3 amps. I would also go with 10 guage to the relay like Misterzz says. Not as much resistance in the wire.

 

well i went ahead and wired up everything today as shown in the second picture. I still need a switch and inline fuse for the main fuse block so i havent tested it over a period of time but i do know that the lights atleast turn on. I guess tomorrow ill finish it up, turn the lights on, and start feeling on the wires. Do you really think that 14 guage wire will catch on fire with that load. The lights that came on my roof rack are walmart el cheapos if that matters at all. Am i really in danger of a fire here??