Siemens HFXD63B175 Molded Case Circuit Breaker

The H in the HFXD6 prefix indicates a high interrupting capacity version of the breaker. The HFXD63B175 has an interrupting rating of 65kA at 480VAC, whereas the standard FXD63B175 is rated for 35kA at 480VAC. Both breakers share the same physical dimensions and panel compatibility.

In Siemens Sentron circuit breakers, the X denotes a non-interchangeable trip unit. The HFXD63B175 is factory-assembled with a fixed thermal trip unit, meaning the 175A rating cannot be modified in the field by swapping the trip unit.

Yes. Because the HFXD63B175 features a non-interchangeable thermal-magnetic trip unit without line-side or load-side restrictions, it is UL Listed for reverse-feed installations when permitted by the equipment and local electrical codes.

No, this is an FD-frame molded case circuit breaker designed for commercial and industrial power distribution. It mounts into Siemens P2, P3, S4, and S5 panelboards or switchboards and is not compatible with standard residential load centers.

The LI designation indicates Long-Time and Instantaneous protection. The breaker uses a thermal-magnetic mechanism where the Long-Time thermal function is fixed at 175 amps for overload protection, while the Instantaneous magnetic function is adjustable to allow for coordination against short-circuit faults.

An HACR rating signifies that the breaker is certified for Heating, Air Conditioning, and Refrigeration equipment. It can safely handle the inrush currents typical of motor-driven HVAC compressors without nuisance tripping.

Yes, the HFXD63B175 is rated for use in DC systems up to 500VDC, offering a 25kA interrupting rating. This makes it suitable for ungrounded UPS systems, battery banks, or other industrial DC circuits.