Schneider Electric QMB-363-T Bus Plug Assembly

Schneider Electric’s Square D QMB363T is a 100 A, 600 V fusible panelboard switch designed to serve as the main switch on QMB fusible power-distribution panelboards. This three‑pole unit (3P) is 7.5 inches in mounting width and is surface‑mounted on the bus assembly; the main switch is factory‑mounted on the bus assembly and cannot back-feed a branch switch. Rated for up to 15 hp motor loads, it provides a robust interlock between utility supply and downstream branch circuits. As a fusible switch, the QMB363T uses replaceable fuses in the field. When integrating into a panelboard, some installations may require a plug‑on extension assembly (for example the QMB310EX) if matching the panel width or chassis style, with Schneider’s guidance noting the 7.5" mounting space and potential extensions for certain configurations. This model is listed as discontinued as of June 12, 2024, though spare parts and select stock may remain through distributors or service channels. The unit carries UL listing and cULus certification, underscoring safety compliance for fusible protective devices in low- to high-hanger panelboard applications.