Square D QMB365WT6 – 400A, 600V, 3-Pole Fusible Panelboard Switch – QMB Series (Class T fuse version)

Introducing the Square D QMB365WT6 — a purpose-built fusible panelboard switch that anchors safe, reliable electrical distribution in demanding environments. This 3‑pole main disconnect is a Class T fuse version designed to pair with Schneider Electric Square D QMB fusible panelboards, delivering dependable load isolation and precise overcurrent protection when it matters most.

Key specifications at a glance

• Amperage: 400 A
• Voltage rating: 600 V
• Poles: 3
• Interrupting rating (KAIC): 200 kAIC
• Series: QMB
• Fuse version: Class T
• Manufacturer: Schneider Electric / Square D
• Part number: QMB365WT6

Why this model stands out

• Built as a cohesive main-disconnect solution tailored for QMB fusible panelboards, converting complex protection into a single, reliable assembly.
• 400 A, 600 V rating supports mid-to-large commercial and light industrial feeders with balanced 3‑pole protection across all phases.
• 200 kAIC interrupting capacity ensures resilience against high fault currents common in demanding installations, improving safety and coordination with upstream protection.
• Fuse‑based protection integrated with a clean load disconnect reduces wiring complexity and panel footprint while simplifying maintenance workflows.

Ideal use scenarios

• Main service disconnects for commercial facilities, data centers, and manufacturing plants.
• Feeder protection within industrial control panels and distribution panels requiring robust isolation and overcurrent protection.
• Upstream protection where a single, dependable Fusible panelboard switch is preferred over multiple components.

What problems it solves

• Consolidates a precise load disconnect with fuse‑based overcurrent protection in one compact unit, lowering wiring complexity and saving space inside panels.
• Provides a clearly defined isolation point to meet code requirements, enabling safer serviceability and easier maintenance checks.
• Facilitates straightforward coordination with Class T fuses selected for the protected circuit, helping you tailor protection to your load profile.

How to maximize performance

• Pair the QMB365WT6 with the appropriate Class T fuses to achieve the intended protection profile for your load.
• Install it as the main disconnect in QMB fusible panelboards to centralize protection and switching in a single assembly.
• Verify that your system’s fault-current levels justify the 200 kAIC rating and that the 400 A rating matches the connected feeders.
• Schedule routine inspections of panelboard connections and maintain proper electrical clearance and safe maintenance procedures.

Why choose Square D QMB365WT6

As part of the QMB Series from Schneider Electric, this fusible panelboard switch offers proven reliability, streamlined installation, and a lifecycle built for demanding industrial and commercial applications. It’s a purpose‑built solution for projects that require a dedicated, fuse‑compatible main switch within a panelboard ecosystem, backed by the enduring safety, performance, and serviceability of the Square D heritage.