Square D KH36125 Molded Case Circuit Breaker

This breaker features an I-Line plug-in connection, making it exclusively compatible with Square D I-Line panelboards and switchboards. It is not designed for load centers or enclosures requiring standard bolt-on or unit-mount breakers.

The KH36125 is part of the legacy K-frame series. While currently obsolete from primary factory production, it remains widely used as a direct replacement breaker to maintain existing 600VAC I-Line distribution systems without requiring a full panel retrofit. Newer panel builds typically transition to PowerPact series equivalents.

The I-Line style plug-in design features robust jaw-like connectors that snap directly onto the bus stack in the panelboard, secured by a retaining screw. This allows for rapid installation and removal, reducing downtime during maintenance or breaker swap-outs.

While the thermal overload protection (long-time) is fixed at 125 amps, the adjustable magnetic (instantaneous) trip allows you to dial in the short-circuit response threshold. This is crucial for properly coordinating with downstream devices and preventing nuisance tripping during temporary inrush currents from large motors or transformers.

The standard mechanical lugs on this breaker are rated for both aluminum and copper conductors, accepting wire gauges from 4 AWG up to 350 kcmil. Always ensure you use the proper torque specifications found on the breaker faceplate when terminating wires.