Indicating fuses are similar to regular cartridge fuses used in electrical service panel boxes. However, when they blow, they offer a visual indication of which fuse on the panel has blown; frequently their design makes a spring-loaded pin pop out when an overload situation occurs, and this pin may in turn press against and close a switch linked to a numbered trouble light on a service panel.

These types of fuses have been adapted by bombers as arming and firing devices. The British Post Office fuse is a slightly different configuration of fuse, regularly used by the Provisional Irish republican Army in certain bombs targeting British police and military personnel.

Securesearch, Inc. makes several different inert IED training aids that are either armed or detonated by the action of the spring-loaded pin of an indicating fuse.