Square D QMB3640-M - 400A, 600V, Fusible, Switch

The Square D QMB3640-M is a robust 400A, 600V fusible switch designed to deliver dependable on/off isolation paired with integrated overcurrent protection. Built for demanding industrial and commercial environments, this compact disconnect keeps powerful motor loads and branch circuits safe, organized, and easy to service.

• Model: QMB3640-M
• Current rating: 400A
• Voltage: 600V
• Fusible: Fusible switch for integrated overcurrent protection

Ideal for motor disconnects, panelboards, and branch circuit protection where space is at a premium and reliable, maintainable protection is essential. The QMB3640-M offers a compact footprint without compromising performance, making it a versatile choice for upgrading or replacing aging disconnects in tighter control rooms or load centers.

Why this fused switch stands out

• Reliable isolation: Delivers a positive disconnect to ensure safe maintenance and servicing of equipment.
• Integrated protection: Fusible construction provides immediate upstream protection for motors and circuits, reducing the need for separate devices.
• Robust, purpose-built design: Built to withstand the rigors of industrial and commercial installations while supporting straightforward maintenance and replacements.
• Clear space efficiency: Designed to fit into standard distribution setups where space is limited, helping you optimize enclosure layouts.

Practical use scenarios include large-motor line disconnects on manufacturing floors, protected branch circuits in distribution panels, and compact motor control configurations where fast, reliable isolation is a top priority. If you’re upgrading from non-fusible switches or consolidating protection into a single, maintainable unit, the Square D QMB3640-M provides a clear, value-driven path to safer, more efficient power distribution.

Tips for best results: pair this fusible switch with the appropriate fuse class and rating per your system requirements, ensure correct wiring practices for 600V systems, and perform routine checks on linkage and mounting to maintain secure, long-lasting operation. With the QMB3640-M, you get a purposeful, job-ready solution that aligns with real-world electrical protection needs.