NH isolating blade size 0 grip lug insulated UL fuse systems Class CC and Class J. The 3NW fuse system from Siemens as an important component of the SENTRON protection components for electrical installations offers effective protection for people, equipment and systems by safely switching off in the event of overload and short circuit. Class CC fuses are used for branch circuit protection applications. Class J fuse links are used for branch circuit protection and in the feeder circuit. The Siemens NW fuses are characterized above all by: 1. Easier export thanks to UL and CSA approval for typical applications in the North American market. 2. Modern design with touch protection ensures safe installation. 3. Possible fuse replacement of the fuse holder when the power is off