Selection of Lyvia Fuses, available as packets of 4 in either 3A, 5A or 13A. A fuse interrupts excessive current so that further damage by overheating or fire is prevented. Wiring regulations often define a maximum fuse current rating for particular circuits. Fuse devices are essential in electrical systems to limit threats to human life and property damage. Fuses are selected to allow passage of normal current and of excessive current only for short periods.