NH stands for “low voltage high rupturing capacity” (from the German: Niederspannungs Hochleistungs Sicherungen). NH fuses have a breaking capacity generally exceeding 100kA, which covers virtually all the short-circuit currents expected to be encountered in low voltage systems.
The NH fuse system, developed by our brand partner, EFEN, is used worldwide, and comprises fuses, solid links, fuse bases and fuse switch disconnects. NH fuses are designed to be used by authorised persons, and as such their design does not provide inherent protection against electric shock; instead, the fuse switch disconnect provides this protection. EFEN SILAS and IN series horizontal disconnects are fully compliant in this regard and EFEN E3 vertical disconnects deliver best practise, with fully shrouded source and load contacts, even in the open position.
NH fuses and links sizes 00, 1, 2, 3 and 4a for which fully standardised bases are available.
There is no minimum operating voltage that must be observed for NH fuses, and they are designed to operate with ac systems from 45-62 Hz.
For most distribution line and cable applications, NH fuses with utilisation category gG are specified. These have full-range breaking capacity for general application, and have a time-current characteristic aligned to meet the current carrying capacity of insulated conductors.
Hiko stocks a range of the most commonly used sizes of gG fuses. Other specialised fuses with different operating characteristics are also available.