The NH system is classified among plug-in fuse systems and is composed of , fuse-base (possibly including terminal covers and phase barriers) , fuse-link with blade contact , fuse-link replacement device (LV HRC fuse puller) Since the design of this system cannot guarantee non-interchangeability of rated current it must be handled by a qualified professional. Type "gG" NH fuse-links are full range breaking capacity fuse-links and are used to protect cables and equipment. They can interrupt any current surge, from the lowest fusing current up to their breaking capacity, and so can be used alone as protection. They also protect electrical devices and industrial set-ups from the electrodynamic effects of very high short-circuit currents.