Square D QMJ366 – 600A, 600V, 3-Pole Fusible Panelboard Switch – QMJ Series

The Square D QMJ366 is engineered for rugged, reliable load disconnect and precise overcurrent protection within QMB fusible panelboards. With a 600 A continuous current rating and a 600 V rating, this 3-pole fusible panelboard switch is built to handle demanding electrical distributions in industrial and commercial environments. When paired with the appropriate fuse class, it delivers clean isolation and fast fault interruption to protect downstream equipment and maintain safe, predictable operation.

Key advantages that set the QMJ366 apart

• High-current capability: 600 A continuous current handling supports heavy-load feeder configurations common in industrial settings.
• Wide voltage compatibility: 600 V rating enables integration with a broad range of medium-voltage panelboard setups.
• Three-pole design: Provides balanced protection and isolation across all three phases for enhanced safety and reliability.
• Robust fault interruption: 200 kAIC interrupt capacity ensures reliable fault clearing without compromising system integrity.
• Series compatibility: Specifically designed for use with QMB fusible panelboards within the Square D QMJ Series ecosystem.
• Trusted brand lineage: Part of Schneider Electric’s Square D lineup, offering industry-standard performance and support.

Why choose the QMJ366? It’s more than a switch—it’s a strategic component for safe, maintainable power distribution. Its three-pole fusible construction provides clear, positive isolation and robust protection for feeders and downstream equipment. By pairing this switch with the appropriate fuse class, you gain tailored overcurrent protection that aligns with your circuit design, reducing damage risk during faults and simplifying maintenance workflows.

Ideal use cases

• Industrial control panels and service entrances that rely on QMB fusible panelboards for protection and disconnecting capability.
• Device and motor control centers where reliable isolation of three-phase loads is essential.
• Critical process lines in manufacturing environments that require predictable interruption characteristics and strong fault handling.

Installation, compatibility, and practical tips

The QMJ366 is designed to integrate into existing QMB fusible panelboard configurations within the QMJ Series. When planning installation, ensure the selected fuse class matches your circuit protection requirements to achieve reliable protection and safe operation. This unit supports streamlined upgrades or replacements in compatible electrical spaces, helping you maintain consistent performance across your QMJ lineup.

• Maintenance planning: Keep a ready stock of compatible fuse classes to minimize downtime during routine maintenance or fault events.
• Protection planning: Consider the 200 kAIC interrupt rating when evaluating protection schemes for systems with high short-circuit current potential.
• Documentation: Record the exact part number (QMJ366) in panel records to simplify future service and parts sourcing within the QMJ Series.

Specs at a glance

• Series: QMJ
• Model: QMJ366
• Current rating: 600 A
• Voltage rating: 600 V
• Poles: 3
• Interrupt capacity: 200 kAIC
• Panelboard compatibility: QMB fusible panelboards in the Square D QMJ Series

Choose the Square D QMJ366 when you need a proven, high-capacity fusible panelboard switch that delivers dependable load disconnect, precise overcurrent protection, and long-term reliability within a trusted electrical ecosystem.