Our compliance agency believes that it is all too likely that a 50 V power adapter is used instead of our 5 V power adapter. Regulation wants a fuse which can protect from 50+ V, and not allow 15 W dissipation in any case.
I am aiming for an IEC/UL approved 500mA fuse, but for overvoltage protection the zener diodes are a bit iffy. The idea is to short circuit any overvoltage to blow the fuse. However the zener diodes will be subjected to a very high power say 5.6 V*1 amp=5.6 W for at least some milliseconds. The power rating of these SOD323 is 300-400mW. One datasheet showed 40W for 100us.
Does anybody have experience with this kind of passive protection? The equipment is solely expected to break and not be repaired and needs to meet IEC/UL standards. I have no room for crowbar solutions.