Originally Posted by Jeep21
I'll be installing a 12000 lbs winch an aux fan and a few sets of lights. About 5 total applications. Would it be bad to do an overkill on the relays lets say use 80 amp relays?
What I would do (did, actually):
Get a fuse box, a fan relay and (2) 30A relays (40A are fine, whatever the part store has):
Blue Sea Systems has pretty awesome fuse boxes, like this http://www.amazon.com/Blue-Sea-Syste...ef=pd_sbs_sg_4
, or you can get a cheapy exposed one for 8$ at the parts store.
The fan relay is dependent on your fan. They pull anywhere from 15A to 50A, depending on make/model.
Light relays are 5$ and all over the part store, 30 or 40A.
You will also need at least 14ga wire for 55W, 12ga for 100W, for best light output, and smaller control wire.
They sell relay harnesses if you keep a tidy house, not required though. Spade connectors work just as well.
Run an 8ga wire to the fuse box input post straight from the battery (keep it close or it needs a fuse, too). Don't hook it up to the pos post until all other wiring is complete.
Run an appropriate wire from a fuse box output slot to the 'power in' terminal (30) on one of your light relays.
Run an 18ga wire from a fuse box output slot to your switch (note: you may want bigger wire to run a control panel for multiple switches instead of a wire for each switch - mine is 14ga, allowing all the switches I want). Connect the other lead on the switch to the 'control input' terminal (86) on the relay.
Run the same size wire used to terminal (86) to ground terminal (85), the ground terminal.
Run the same size wire used to terminal (30) to run a power line to the first light. You can buy 3 way connectors, or do what i did. Slice open the pos line, "skin" about an inch of the insulation off, and splice in an equal gauge wire by soldering the connection. I am sure youtube can elaborate. Connect the splice to light one and run the original wire to light two.
Repeat as needed for light pairs. If you are after all lights on one switch we can do that, too, but it gets a little trickier depending on how many/how bright.
Do the same thing for the fan, through the fuse box, assuming it a lower amperage (<30A) fan, hooking into the relays the same way. If it is higher amperage fan it and (4) 100W lights may exceed the fuse box ampacity.
You can trigger the entire fuse box off an ignition source with a relay, or leave it wired to work without the key - or do one of each.
As for the winch, it depends on the type of solenoid(s) you have as to how to wire it, but in cab switches are very possible and - as Jerry said - require no relays.
(2) 55W lights = 15A fuse
(2) 100W lights = 20A fuse
Switch control = 5A fuse
I run 3 relay controlled switches and 5 low watt interior lights off my interior leg, all on a 10A fuse, which any 18ga will handle and I can have it all on at once. I ran 14ga though. What can I say, I had more of it laying around, lol.
You can always upgrade your headlights to relay controlled higher gauge wiring while youre in there, best mod I've done so far.
You can find some 5 post relays, that simplifies it a bit, but this way I found to be simlplest with common parts.