Quote: The size of the fuse didn’t matter because it was a 625 CCA battery going direct to ground.
Exactly - and that is why an 80 amp fuse on the brown wire is probably safe. During a dead short event, the current is very high (well over 80 amps) and the fuse will blow within a second (and probably a fraction of a second). Although the wire is carrying much more current than it could safely sustain, it can easily carry 200 amps for a fraction of a second without getting hot enough to cause damage.
60 amp is probably still safer on the MGB if it is heavy enough to withstand the spikes when devices first power on. And, the brown wire could withstand a constant 60 amp current without melting. (In theory, it could withstand a constant 80 amp load, but I'm pretty sure it would be somewhat warm!)
Edited 1 time(s). Last edit at 2018-02-13 06:22 PM by ingoldsb.