Time-delay, nonindicating midget fuses tolerate temporary inrush currents without opening, which prevents nuisance-blowing from motor and equipment startups. Also called slow-blow midget fuses, they open to disconnect an electrical circuit when exposed to sustained loads and short circuits. They have no indicator for identifying a blown fuse, so they're sometimes used with an indicating fuse block or cover.

Fast-acting, nonindicating midget fuses open within seconds of being exposed to overloads and short circuits. Also called fast-blow midget fuses, they are highly sensitive to changes in current flow and don't tolerate temporary overload currents or power surges. They have no indicator for identifying a blown fuse, so they're sometimes used with an indicating fuse block or cover.

Time-delay, indicating midget fuses tolerate temporary inrush currents without opening, which prevents nuisance-blowing from motor and equipment startups. Also called slow-blow midget fuses, they open to disconnect an electrical circuit when exposed to sustained loads and short circuits. They have a visual indicator to make it easier to identify blown fuses for replacement.