Siemens NSB BQD140 Miniature Circuit Breakers

Siemens BQD140, a 1‑pole circuit breaker rated for 40 A at 277 VAC, provides fast and predictable overcurrent protection for a single branch circuit. It features a thermal‑magnetic trip and a 14 kA interrupting capacity, making it suitable for typical commercial and light industrial applications where a 277 VAC supply is used; continuous current rating at 40°C ambient is 40 A, and the device is designed for bolt‑on installation in compatible Siemens panels. The BQD140 belongs to Siemens' BQD/CQD molded‑case family, delivering reliable short‑circuit protection with a straightforward wiring footprint and a single‑pole design that guards the hot conductor while leaving other conductors unaffected. Common applications include protecting lighting circuits, receptacle circuits, and small motors in commercial/industrial distribution panels, where compact single‑pole protection at 277 VAC is required.