Square D KC34150 Molded Case Circuit Breaker

Facilities looking to upgrade this legacy K-Frame breaker can substitute it with the PowerPact J-frame series, specifically the JJA36150. Both provide 150 amps of protection and share the I-Line plug-on mounting design, though you should verify panel space and short-circuit coordination before retrofitting.

The breaker comes standard with load-side lugs, specifically catalog number AL250KA, that accept copper or aluminum wire ranging from 4 AWG to 350 kcmil. Always use a calibrated torque wrench and adhere to the torque specifications printed on the breaker label during installation.

The breaker utilizes Square D's I-Line plug-on design. The jaws snap directly onto the bus stack of an I-Line panelboard or switchboard, and a mounting foot on the back of the breaker bolts directly to the panel's mounting pan. No additional bus hardware is required.

The prefix designates the interrupting capacity. While KA, KH, and KC models are all legacy K-Frame I-Line breakers, the KC34150 is the Extra High capacity version. It safely interrupts up to 65kA at 480VAC, which is critical for applications where available fault currents exceed standard or high-interrupting thresholds.

Yes, but only the magnetic portion. The breaker features a thermal-magnetic trip unit with Fixed Thermal and Adjustable Magnetic settings. The thermal overload threshold is fixed at 150 amps, while the instantaneous magnetic trip can be dialed in by the installer to coordinate with downstream equipment and prevent nuisance tripping during motor inrush.

No. The KC34150 features an I-Line plug-in connection and is exclusively designed for use with Square D I-Line panelboards and switchboards. It will not fit in standard QO, NQ, or NF panelboards.

Yes. Due to the plug-on bus connections, I-Line breakers require proper alignment and pressure to snap onto the bus stack. Installation must only be performed by a qualified electrician, and the panelboard must be completely de-energized to prevent arc flash hazards when engaging or disengaging the jaw contacts from the live bus.