Ignition With Fuses?

Ahhh. So it’s not about the amp fuse size as much as just protecting the wires from melting down and a fire? Yes I know there is also protection to the “part” as well. So since I am over on my wire size it can handle bigger TCSN normal fuses without issue? Thus if choosing to go the circuit breaker route a big 125A breaker will still break at the smallest of shorts?

 

125A seems excessive. I would worry it would not be fast enough to stop the wire from melting before it opens. All your lights only draw maybe 10 or 15 amps, and the heater fan maybe another 5, and the ignition an amp or two. Heavy lifting for the alternator/generator is recharging the battery after starting, not running the accessories.

Anything with moving parts (like a circuit breaker) has some chance of failure. It's also vulnerable to corrosion and weather/water. A fusible link is a piece of wire with fireproof insulation. Connected with good splices, they are as reliable as the wire itself. Protect the wires.