GMT fuses have a small inherent electrical resistance resulting in a small inherent power loss. Fuses with a higher current rating will get hotter and thus cause greater than average power loss.

The GMT fuse manufacturer recommends that the load for GMT fuses up to and including 7.5A not exceed 80% of the fuse rating and that the load for GMT fuse sizes between 10A and 20A not exceed 70% of the fuse rating. For example, the load for a 15A GMT fuse should not exceed 10.5A (15A x .70 = 10.5A).