Bart,
This is how I had mine wired:
12V from fuse block to relay, then from relay to fan (so this is the fused power supply to fan)
Then I had an un-fused small wire (22 guage) from 12V power to toggle switch, then same size/color wire from toggle switch to switch terminal on the relay. Then the 4th post (other side of the switch portion) of the relay to ground. I used regular automotive grade relays. If you run to the JY, you can pull them all day long and walk out with a pocket full of them....payment optional