Current-Limiting Fuse Classes

Reference basis uses manufacturer current-limiting fuse descriptions; product-specific curves and equipment labels govern engineering review.
Fuse class	Current-limiting reference	Common voltage labels	Curve boundary	Boundary
Class J	Commonly described as current-limiting	250 V, 600 V	Curve review needed for actual let-through	Current-limiting wording does not replace manufacturer curves
Class CC	Commonly described as current-limiting	600 V	Curve review needed for actual let-through	Current-limiting wording does not replace manufacturer curves
Class RK1	Often current-limiting in comparison literature	250 V, 600 V	Curve review needed for actual let-through	Current-limiting wording does not replace manufacturer curves
Class RK5	Often current-limiting in comparison literature	250 V, 600 V	Curve review needed for actual let-through	Current-limiting wording does not replace manufacturer curves
Class L	Commonly current-limiting in manufacturer literature	600 V	Curve review needed for actual let-through	Current-limiting wording does not replace manufacturer curves

Use notes

Use this table for preliminary reference and arithmetic checks only.
Confirm equipment ratings, product markings, installation conditions, utility requirements, and the local authority requirements before design or field use.

Reference table