Siemens QJ23B150 Molded Case Circuit Breaker

This QJ-frame breaker installs into Siemens P1, P2, and P3 panelboards, as well as compatible switchboards and meter centers. Depending on whether you are installing it as a main or branch breaker, your panel may require a specific QJ mounting kit or strap kit.

Yes. Siemens has transitioned to the QR frame, and the QR23B150 is the direct drop-in replacement for this model. The updated QR23B150 shares the same physical footprint and panel compatibility as the older QJ23B150.

No. The QJ23B150 is equipped with a thermal-magnetic trip unit featuring fixed long-time and instantaneous (LI) protection. The trip curve is factory-calibrated and does not feature field-adjustable dials.

The standard load-side lugs are dual-rated for both copper and aluminum conductors. They accept 6 AWG to 300 kcmil for copper wire, and 4 AWG to 300 kcmil for aluminum wire. Always apply a listed oxide-inhibiting compound when terminating aluminum conductors.

No. This is a bolt-on, unit-mount molded case circuit breaker designed for commercial panelboards and switchboards. It will not fit into standard plug-on or bolt-on residential load centers that require QP, BQ, or BL style branch breakers.

No. This breaker has a maximum voltage rating of 240VAC. Connecting it to a 480V or 600V system violates its UL listing and presents a severe safety hazard.

The QJ23B150 has a maximum interrupting rating of 10kAIC at 240VAC. If your system's available short-circuit current exceeds 10,000 amps, you must select a higher-rated breaker, such as a 22kAIC or 65kAIC version within the QJ or QR family, to comply with National Electrical Code (NEC) requirements.

Yes. When paired with the appropriate main breaker mounting kit, such as the MBKQJ3150 for Siemens P1 panelboards, this 150A unit can serve as the main overcurrent protection device for the panel.