I think it would be best to draw power from the horn relay rather than the battery or existing fuse box wiring. The alternator provides power directly to the horn relay. The factory wires off the horn relay are usually 10g between the horn relay and battery, and 10g between relay and fuse box, which is insufficient to allow another 70A draw to your new fuse box.
In your diagram swap pins 85 and 86. 85 is the ground and 86 is the trigger. These wires only need to carry about 1A current, so 18g wire is more appropriate.
More important is to match the wire gauge for the load circuit, so 8g wire on pin 30 must match 8g wire on pin 87.
I would recommend instead of a fuse between the battery and relay, to use a self-resetting circuit breaker of the appropriate amperage. These are about $10.
8g wire with THHN insulation is good for about 70A given the short length involved. Is that sufficient for everything that will draw from the new fuse block?
In your diagram swap pins 85 and 86. 85 is the ground and 86 is the trigger. These wires only need to carry about 1A current, so 18g wire is more appropriate.
More important is to match the wire gauge for the load circuit, so 8g wire on pin 30 must match 8g wire on pin 87.
I would recommend instead of a fuse between the battery and relay, to use a self-resetting circuit breaker of the appropriate amperage. These are about $10.
8g wire with THHN insulation is good for about 70A given the short length involved. Is that sufficient for everything that will draw from the new fuse block?
