Fuses protect the power side of security and low-voltage equipment from a surge or a short: small replacement fuses sized for access-control power supplies and related devices, the kind that sacrifice themselves to prevent a wiring fault from damaging the equipment behind them. When a power supply stops delivering output but otherwise looks intact, a blown fuse is one of the first things worth checking.
Match the fuse exactly to the amperage and type the equipment specifies - a fuse rated too high defeats the protection it is meant to provide, and one rated too low fails under normal load. Keep a small stock of the correct fuse rating on hand for any installed power supply, since a blown fuse is one of the fastest fixes available if the right replacement is already on the shelf. Investigate why a fuse blew before simply replacing it; a repeat failure usually points to a wiring or load problem that needs attention. COLAMCO supplies fuses alongside the access-control power supplies business, government, and education security programs install.