North American Classes Of Fuses

The North American fuse industry has developed a number of Classes or Standards for fuses with voltage ratings of 600 volts or less. These classes include basic physical specifications and performance requirements.

Class CC 600V; up to 30A; 200kA Cylindrical contact, 10 x 38mm with rejection feature.
Class G 300V; up to 60A; 100kA Cylindrical contact, 10mm diameter
Class H 250 and 600V; up to 600A; 10kA NEC* dimensions.
Class J 600V; up to 600A; 200kA Non interchangeable dimensions
Class K 250 and 600V; up to 600A; 50, 100 or 200kA NEC* dimensions.
Class L 600V; 601 to 6,000A; 200kA Bolted connections.
Class R 250 and 600V; up to 600A; 200kA. NEC* dimensions; rejection feature.
Class T 300 and 600V; up top 600A; 200kA Compact dimensions, fast acting.

* NEC dimensions — National Electric Code dimensions, often referred to as Code Dimensions.