Square D FC34050 Molded Case Circuit Breaker

The plug-in jaw design mounts securely onto the bus stack of Square D I-Line switchboards and distribution panelboards.

Yes, it is fully compatible with legacy Square D QED switchboard sections designed to accept standard F-frame molded case circuit breakers.

The line side features a tension jaw assembly that presses directly onto the panelboard bus. Only the load side requires cable termination, significantly reducing wiring time compared to unit-mount alternatives.

Because the line side connects directly to the panelboard bus via tension jaws, only the load-side mechanical lugs require manual cable termination. These load lugs accept copper or aluminum conductors.

It utilizes fixed thermal and magnetic sensing elements. The Long-time (L) thermal element protects against gradual, sustained overloads, while the Instantaneous (I) magnetic element responds immediately to severe short circuits.

Square D transitioned the legacy F-frame family into obsolescence, replacing it with the updated PowerPact series. However, original FC models remain available for exact component matching in existing setups.

Facilities upgrading their equipment can cross-reference this unit to the PowerPact HJA36050 replacement, which maintains the identical capacity and high-level interrupting ratings.

No, standard legacy F-frame breakers are rated for continuous loads up to 80 percent of their maximum capacity. They should not be used for 100 percent continuous load applications unless specially marked.

While I-Line architecture is modular, safe working procedures dictate entirely de-energizing the switchboard or panelboard bus before pressing the breaker jaws into place to eliminate arc flash risks.