Square D QMB325W – 400A, 240V, 3-Pole Fusible Panelboard Switch – QMB Series

Meet the Square D QMB325W—a rugged 400A, 240V, 3-pole fusible panelboard switch engineered for dependable load disconnect and precise overcurrent protection within Schneider Electric’s QMB fusible panelboards. As a core component of the trusted Square D QMB Series, this single fusible switch delivers reliable fault isolation and streamlined maintenance when paired with the appropriate fuse class, making it essential for demanding industrial environments with heavy three‑phase loads.

Key capabilities

• Three-pole architecture ensures synchronized disconnection across all three phases, substantially reducing arc flash risk during servicing and improving fault localization.
• 400A, 240V rating supports large feeders and heavy motor circuits, delivering robust protection for industrial equipment and processes.
• 200 kAIC interrupting capacity at 240V provides solid fault handling for high-energy systems and minimizes downstream impact during faults.
• Seamless QMB compatibility—engineered to pair with QMB fusible panelboards to maintain protection coordination when used with the correct fuse class.
• Maintenance-friendly design offers reliable isolation, simplifying servicing and reducing downtime in critical production lines.

Ideal use cases

• Service feeders and large motor circuits in manufacturing, processing, mining, and heavy machinery facilities requiring robust, code‑compliant protection.
• Primary protection for three‑phase distribution panels where dependable fault isolation is a priority.
• Upgrade or replacement path within existing QMB installations to enhance protection coordination and fault localization.
• Situations where synchronized, multi‑phase disconnection lowers maintenance risk and improves safety for personnel.

Installation, compatibility, and practical guidance

• Always pair the QMB325W with the correct fuse class to ensure intended protection and coordination with downstream devices.
• Confirm panelboard compatibility and mounting provisions within the QMB family to maintain proper electrical and mechanical fit.
• Follow appropriate safety and wiring practices for three‑phase switches, including torque specifications and required clearances during installation and maintenance.
• Ensure wiring gauges and conductor sizing are appropriate for 400A at 240V to optimize performance and safety.

The Square D QMB325W is a purpose‑built, high‑current solution for robust three‑phase protection in QMB panelboards—delivering reliable load disconnect, precise fault isolation, and streamlined maintenance in industrial settings where dependable isolation matters most.