This guide applies to low-voltage power circuit breakers of the 600-volt insulation class with separately mounted current-limiting Class J and Class L fuses for use on ac circuits with available short-circuit currents of 200 000 amperes (rms symmetrical) or less. Low-voltage integrally fused power circuit breakers (see American National Standard Low-Voltage AC Integrally Fused Power Circuit Breakers, C37.28-1969) and combinations of fuses and molded-case circuit breakers are not covered by this guide.

This guide applies to low-voltage power circuit breakers of the 600-voIt insulation class with separately mounted current-limiting Class J and Class L fuses for use on ac circuits with available short-circuit currents of 200 000 amperes (rms symmetrical) or less. Low-voltage integrally fused power circuit breakers (see American National Standard Low-Voltage A C Integrally Fused Power Circuit Breakers, C37.28-1969) and combinations of fuses and molded-case circuit breakers are not covered by this guide

This guide sets forth recommendations believed essential for the selection of Class J and Class L current-limiting fuses meeting NEMA Standard on Low-Voltage Fuses, FU 1-1966, and American National Standard Low-Voltage Cartridge Fuses 600 Volts or Less, C97.1-1972, for use in combination with low-voltage power circuit breakers, rated in accordance with American National Standard Low-Voltage AC Power Circuit Breakers (600-Volt Insulation Class) C37.13-1963.