Its been a while sence Iv posted here, but I almost have my roof rack built, and Im now looking into wiring the lights on it.. Could someone please tell me what a relay is for? I know that its a switch (moreless), but why is one needed? Why would you turn on a swich just to have it turn on another swich? What is the purpose of it??
thanks
jason

 

It is a switch, it lets you switch a larger current with a smaller current. When you complete the circuit on a relay it closes a set of contacts that allow you to use a high current through the set of contacts but is switched by just a light current.. So instead of needing to run heavy wire and a heavy switch you can use light gauge for the switching part. I like using them not only because of that but it also isolates what you added from the factory electrical system. I've added them for my starr hids, a set of hid fogs, a flir system and added one that will turn on my fogs whenever I use my brights (added a factory switch powered from the headlight relay and grounded by the hi/lo relay to complete circuit)

 

the wire part is true. the isolation is not. and it doesnt matter.
both the switch with heavy wire,and the relay, must connect to the exact same 12 system point thru what could be the same fuse. at that point there is no isolation.

 

i like to run directly from battery with inline fuse to the #30 (i think) terminal of the relay and usually try and retain factory wiring for the switching.

 

thanks.. i was going to use them, but i just wasent sure what they did, or how they worked.
jason

 

OK,, back to the relay thing. I have 4 150w lamps, and 2 50w lamps,
they will be on 3 switches, 1 switch for the back 2 50w's, 1 switch for the 2 forward facing outside lamps (150w each), and 1 switch for the 2 forward facing center lamps (150w each). the forward facing lamps are on a roof rack. So if I got this right, I add all of the watts up (700 watts) and devide that by 12. That comes out to 58 and some change.
I wont be running all lights at the same time, if anything, the only ones that will be running at the same time would be the 4 frount ones (600 watts).
heres my question, could I get one 60+ amp relay and run ALL the lights into that one relay, or will I need multiple relays? Im kinda confused about it, but I want to get it right.
thanks for the help
jason

 

Jason,
You need 1 relay per switch.
How it works is, you wire a light wire gauge circuit to your switch. The switch turns on the coil of the relay. The relay contacts close when energized by the switch. The circuit wired thru the relay contacts needs to be rated (amp wise) to handle the lighting load, in your case a pair of lights. When the relay contacts close, your lights turn on.

 

X2 on what Bunger said. Also don't skimp on the wire going to the relay, and coming from the relay to the lights. 10 gauge minimum for each of your 3 runs will be sufficient.

 

gigantic lites huh?, bigger than headlights huh?lets see pix ok.

 

thanks for the reply!, Im glad I ask. Each of the relays needs a power from the battery right? If so, can this power be daisy chained from one relay to the next, or do I need one of those terminal block things to pull power for each one individualy?
thanks again!

@ Broken Halo, I planed on using using 10g for my heavy power, and 12g to my toggles. Im sure that the 12g is overkill,,, but what the hay.
thanks!

@ Drtom, oops my bad, there 130w eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices
there not the best, but I think theyll suit my needs.
thanks!
jason