Siemens BQD120 - 20 A, 277 V, 1-Pole Bolt-On Circuit Breaker | AmpState

Designed for reliable branch-circuit protection in panelboards and load centers, the Siemens BQD120 delivers precise 20A, 277V performance in a compact, easy-to-mount molded case. This 1-pole bolt-on breaker is built to keep electrical systems safe and running smoothly in demanding environments.

Why the Siemens BQD120 stands out

• Secure bolt-on mounting: A rigid, vibration-resistant connection minimizes loosening over time and helps maintain a stable bus contact in busy electrical rooms.
• Thermal-magnetic trip unit: Combines thermal and magnetic sensing for dependable, repeatable protection against overcurrents and short circuits, with fast, predictable response.
• OEM compatibility: Designed to be used with matching Siemens OEM load centers and panelboards, ensuring proper fit, electrical performance, and streamlined installation.
• Versatile applications: Suitable for residential, commercial, and light industrial installations where 277V circuits are common, such as lighting and general-purpose branch circuits.

Technical snapshot

• Manufacturer: Siemens
• Part number: BQD120
• Type: Thermal-magnetic molded case circuit breaker
• Amperage rating: 20A
• Voltage rating: 277V
• Number of poles: 1
• Mounting style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Use cases and scenarios

• Upgrade or retrofit a 20A lighting or general-purpose circuit in commercial spaces powered by 277V.
• Install in residential or light industrial panels where a robust, vibration-resistant connection is beneficial in environments with mechanical noise or frequent equipment startup.
• Pair with matching Siemens panelboards to maintain consistent electrical protection characteristics across the enclosure.

Who benefits most

• Electrical contractors and facilities managers needing reliable, code-aligned protection in panelboards and load centers.
• Builders and remodelers configuring 277V branch circuits for commercial lighting, office spaces, or light industrial setups.
• Maintenance teams seeking a durable, easy-to-install bolt-on solution that resists loosening in vibration-prone environments.

With the Siemens BQD120, you gain a purpose-built, dependable solution for protecting branch circuits from overcurrent and short circuits—delivering consistent protection performance, secure mounting, and OEM-friendly compatibility for streamlined installations.