Square D QMB366W – 600A, 600V, 3-Pole Fusible Panelboard Switch – QMB Series

Introducing the Square D QMB366W—a rugged 3-pole fusible panelboard switch purpose-built for reliable load disconnect and precise overcurrent protection in demanding three-phase power distributions. With a 600 A, 600 V rating and a 200 kAIC short-circuit capability, the QMB366W is engineered to withstand high fault currents while delivering coordinated protection when paired with the appropriate fuse class for your panelboard configuration.

Key specifications at a glance

• Amperage: 600 A
• Voltage: 600 V
• Poles: 3
• KAIC (short-circuit rating): 200 kAIC
• Series: QMB
• Part Number: QMB366W
• Manufacturer: Schneider Electric / Square D

Why this matters in real-world setups

• Three-pole protection for balanced three-phase systems: ensures all phases switch together, reducing the risk of phase imbalances during faults and enabling clean, predictable disconnection.
• Integrated load disconnect with overcurrent protection: combines switching and protective functions in a single, compact device, simplifying panel design and maintenance while ensuring coordinated protection with the correct fuse class.
• High fault current capability: a 200 kAIC rating supports sizable upstream fault currents when used within approved panelboard configurations, enhancing system reliability.
• Trusted ecosystem: part of the proven Square D QMB Series, designed to work smoothly with other QMB components for cohesive system protection and easier maintenance planning.

Best-fit applications

• New installations in industrial control rooms, manufacturing lines, and large commercial electrical rooms that rely on three-phase power.
• Retrofits or upgrades of existing QMB fusible panelboards to enhance protection, reliability, and code compliance.
• Service disconnect points in feeders requiring a clear, code-compliant isolation device.

What sets the QMB366W apart

• Specifically engineered for QMB fusible panelboards: aligns with mounting, fuse classes, and coordination requirements to help you meet safety standards consistently.
• Direct pathway to robust protection: pairing with the appropriate fuse class delivers dependable overcurrent protection without the need for separate, parallel devices.
• Coordinated system protection: designed to operate as part of a complete protection scheme within the QMB Series ecosystem, simplifying upgrades and ongoing maintenance.

Installation and optimization tips

• Verify the panelboard’s fuse class requirements and ensure the selected fuse type matches your protection scheme for the specific application.
• Plan for three-phase fault scenarios in your protection coordination study to confirm that the 200 kAIC rating provides the intended level of protection for upstream faults.
• Keep a record of part number QMB366W to streamline future replacements, inventories, and compliance documentation.
• Schedule seasonal and routine inspections to confirm fusible links and the disconnection mechanism operate smoothly and reliably.

With the Square D QMB366W, you’re choosing a purpose-built solution that integrates seamlessly into the QMB series, delivering dependable isolation and coordinated protection for complex three-phase power environments. It’s the practical, scalable choice for modern industrial control rooms, manufacturing lines, and large commercial electrical spaces where reliability and safe shutdown are non-negotiable.