Square D QMJ365 – 400A, 600V, 3-Pole Fusible Panelboard Switch – QMJ Series

Square D QMJ365 is a rugged 3-pole fusible panelboard switch engineered for dependable load disconnect and robust overcurrent protection in three-phase power systems. Rated for 400 A at 600 V, it integrates seamlessly with QMB fusible panelboards to deliver a compact, space-efficient protection solution for demanding industrial and commercial environments.

Key specifications

• Amperage: 400 A
• Voltage rating: 600 V
• Poles: 3 (three-phase)
• Interruption rating (KAIC): 200 kAIC
• Series: QMJ
• Part number: QMJ365
• Compatibility: designed for use with QMB fusible panelboards with appropriate fuse class

Why the QMJ365 matters

Combining a rugged switching mechanism with fuse-based protection, the QMJ365 provides a clear, dependable load disconnect while interrupting fault currents up to 200 kAIC. This enables rapid isolation of faulty circuits, minimizes collateral damage, and creates safer maintenance windows for technicians working on three-phase systems.

What sets it apart

• 3-pole design aligns with standard three-phase feeders, simplifying installation and ensuring balanced protection across all phases.
• Built to the durable standards of Square D, reducing downtime and service calls.
• Precisely engineered to work with QMB fusible panelboards, delivering a cohesive, space-efficient protection solution within your distribution scheme.
• When paired with the appropriate fuse class, you gain reliable overcurrent protection alongside a straightforward load disconnect path.

Ideal use cases

• Industrial facilities with three-phase motors, conveyors, or heavy equipment requiring reliable load isolation.
• Panelboard upgrades or retrofits where QMB panels are already in service and need a compatible fusible switch.
• New installations in warehouses or manufacturing lines where space is at a premium and a single integrated protection device simplifies wiring and maintenance.

Practical tips for best results

• Pair the QMJ365 with the correct fuse class as specified for your QMB configuration.
• Verify proper three-phase wiring and clear labeling on the panelboard to facilitate quick isolation during fault conditions.
• Schedule periodic inspections of connections and ensure fuse availability aligns with your maintenance plan.
• Engage qualified personnel to install in accordance with local electrical codes and standards.

The Square D QMJ365 is more than a switch — it's a purpose-built combination of load disconnect and overcurrent protection that helps keep three-phase distributions running smoothly while simplifying maintenance and safety compliance.