Siemens BQD120 Single Pole Thermal Magnetic Circuit Breaker

Siemens BQD120 is a 1-pole molded‑case circuit breaker in the BQD family, rated for 20 A at up to 277 VAC and 125 VDC. This bolt‑on, single‑pole device uses a thermal‑magnetic trip to provide overload and short‑circuit protection, with an interrupt rating of 14 kA at 277 VAC. It features a low‑tab connection and panel mounting compatibility for practical enclosure installation, and accepts copper or aluminum conductors in the 14–6 AWG range. The compact unit measures roughly 4 in long, 3 in wide, and 1 in high, making it suitable for distribution panels in commercial or light industrial environments with 277 VAC distribution. As part of Siemens’ BQD series, the BQD120 is intended for branch circuit protection in single‑phase applications, where a 20 A protective rating aligns with standard lighting and general power circuits; its 40°C ambient rating allows operation in typical indoor electrical rooms. Overall, the BQD120 provides reliable, bolt‑on protection for a dedicated 20 A branch circuit, combining thermal and magnetic trip elements in a compact package.