Originally Posted by Rand
normal automotive relays draw 1-3amps each. (generally)
No way. Maybe a starter relay. But the typical 12 volt accessory relays are less than 1amp, most less than 500ma.
I'm not sure what wattage the lights you're getting are. The rating of the relay will determine how many relays you need. Using the 125% rule:
100 Watt lights: 45 amps
(3) 20 amp relays
(2) 30 amp relay
150 Watt Lights: 67 amps
(4) 20 amp relays
(3) 30 amp relays
The high current feed to each relay should be fused according the the relays current rating. A 30 amps relay gets a 30 amp inline fuse feeding it. Do not
just put one big 60 or 80 amp fuse and split to each relay. You can very easily cook the relays or burn the wires and your truck down if something shorts or is not working properly.