The following reference document provide information about construction, application, and definitions of low-voltage industrial fuses.

Low Voltage Cartridge Fuses | NEMA FU 1-2012

Covers eight classes of low voltage cartridge fuses consisting of a current-responsive element inside a fuse body with contacts on both ends, rated 600 V or less, ac and dc. The classes are G, H, J, K, L, R, T and CC. Includes updates to the definitions, voltage rating and interrupting rating tables and the current carrying and temperature rise tests.