What Pynzo said, I believe they want 4 numbers (2 sizes) larger (which as you know is smaller gauge) as they only go up or down in even numbers so a 12 GA FL in an 8 GA wire is (2) sizes. I ain't up on electronics but I'd prefer a circuit breaker of the right type. I had a 66 dart that by itself overnight (diode in alt I believe) acted up & the wiring from alt to bulkhead & more/some on bulkhead to batt iirc was severely melted & the FL did not open