Please elucidate me as to the relevance of circuit capacity with regards to thermal/wattage issues? Next demonstration. Grab a handful of AGC 30 fuses. Impress 40 amps at 6V across one. Then 35 amps at 36 volts? OOoooo the 35 amps at 36 volts blows the fuse but how about the 6 volt fuse? This is why fuse sizing is an engineering art and not merely rough amperage.
Actual testing and experience with fuse ratings and action reveals some eye-openers. It is very true that lower voltage fuses are not as sensitive thus have a broader tolerance percentage compared to >50 volt devices. But then again many low voltage electronic devices tolerate a operation tolerance range from 10 to 15 volts. Not as many electronic devices operate well ranging 100 - 150 volts.