Siemens BQ3B040N Three-Phase Molded Case Circuit Breaker

Siemens BQ3B040N is a three-pole, general‑purpose molded‑case circuit breaker (MCCB) from the Siemens BQ family, rated 40 A at 240 V AC for branch‑circuit protection in commercial and light industrial panels. It uses a bolt‑on mounting style and a common‑trip design across all three poles, enabling coordinated protection for multi‑line feeders in enclosed power distribution assemblies. The unit employs a thermal‑magnetic trip mechanism to provide overcurrent protection and delivers a 10 kA interrupting rating at 240 V, making it suitable for distribution feeders, motor circuits, and transformers within Siemens panels or compatible enclosures. As a 3P, 240 V, 40 A device, it is a straightforward replacement or upgrade for existing BQ installations and aligns with Siemens general‑purpose MCCB applications where reliable, field‑serviceable protection is required. The BQ3B040N’s bolt‑on design and common‑trip three‑pole configuration help ensure consistent protection across phases while maintaining a compact molded‑case footprint in standard Siemens panel architectures.