ISO cover for NH base size 1 NH fuse system 3NA, 3ND for selective line and system protection. The NH fuse system from Siemens as an important component of the SENTRON protection components for electrical installations offers effective protection of people, equipment and systems by safely switching off in the event of overload and short circuit. Compared to circuit breakers, higher short-circuit currents can be achieved with better current limitation at the same time. The NH fuse system is characterized above all by: 1. Combination indicators signal the fuse has been switched off by a clear color change from red to white. 2. Greater safety when changing thanks to insulated grip tabs. 3. High selectivity at low cost. 4. Long-term and safe operation thanks to silver-plated contact blades. 5. Fuse links from 2 A to 1250 A and available in sizes 000, 00, 0, 1, 2, 3, 4 and 4a.