Mersen Fuse: 40 A Amps, 600V AC, 1-9/16 in L x 13/16 in dia Fuse Size, Cylindrical Body

Very-fast-acting nonindicating UL Class T fuses open circuits even more quickly than fast-acting fuses when exposed to overloads and short circuits. They're commonly used to protect solid-state electronics. These very-fast-blow fuses 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.

UL Class T fuses are very small fuses that require minimal installation space for protecting electrical feeders and branch circuits from overcurrent. These fuses have an interrupting rating (IR) of 200kA and are not interchangeable with any other UL fuse class. They are current-limiting to prevent electrical damage by disconnecting circuits before they're exposed to the full magnitude and duration of an overcurrent.