External fuse protection, UL-compliant

Use UL circuit breakers of class RK5 for the mains-side fuse protection.

The integrated protection against short circuit is no substitute for the external fuse protection of the supply network. The fuse protection of the supply network must comply with the manufacturer's specifications and the national and international regulations and laws.

Can be used in supply networks with a maximum current-carrying capacity of 18,000 A at 480 V AC. For alternatives to UL Class RK5 circuit breakers, be sure to refer to UL Standard UL 508 A, Chapter SB4.2.3, Exception No. 1. For further questions regarding UL circuit breakers, please contact the appropriate certificate authority.

SB4.2.3 A high fault short-circuit current value for a motor controller, overload relay or combined motor controller as specified in SB4.2.2 (a) or (c) may be used as the short-circuit current value of the component if the specified branch circuit protection device is provided.

Exception 1: Where the specified BCPD is a Class CC, G, J, L, RK1, RK5 or T fuse with respect to the high fault SCCR, a fuse of a different class may be used at the same high fault rated power, provided the Ip let-through current and I2t of the new fuse are not greater than that of the specified fuse. See table SB4.2 for maximum let-through currents (Ip) and I2t.

Single-phase

Three-phase