What should one look for in fusible electrical protection hardware to avoid insurability issues?
I think this is an over generalized thought. Since you mentioned 480, many industrial equipment sets using variable frequency drives require class j fuses for protection, their are still some AC units that state max fuse size (most have changed to max fuse or hvacr breaker in the last few years) in these cases it would violate the listing to use a breaker. I have updated quite a few homes in my area from fused to breakers because of insurance requirements but there are still companies that will insure homes with fuses or even FPE stablock panels, where fuses would be safer if properly sized in my opinion. I think the bigger problem is on fused system k&amp;t or cloth wrapped wire was used and some of that insulation is failing being the root cause of the problem.