Siemens BQ2B125 - 125 A, 240 V, 2-Pole Bolt-On Circuit Breaker | AmpState

Siemens BQ2B125 is a 125 A, 240 V, 2-pole bolt-on molded case circuit breaker designed to deliver reliable branch circuit protection in panelboards and loadcenters. Built for environments where connections must stay solid under vibration, this breaker locks onto the bus with a secure bolt-on mounting, helping minimize movement that can lead to loose connections over time.

With a thermal-magnetic trip unit, the BQ2B125 provides stable, repeatable protection against both overloads and short circuits. The thermal element handles gradual overcurrent, while the magnetic element responds quickly to high-current faults, helping protect wiring and devices from damage and reducing nuisance trips in everyday use.

Why this breaker stands out

• Rigid bolt-on mounting keeps the breaker firmly connected to the bus, supporting long-term reliability in vibration-prone installations.
• Thermal-magnetic protection delivers predictable trip behavior, so you know exactly when and why the breaker will trip.
• OEM-compatible design is built to work with matching Siemens loadcenters and panelboards for a cohesive, plug‑and‑play installation.
• Versatile across applications suitable for residential, commercial, and light industrial panel setups, giving you a single solution for multiple environments.

Technical specifications at a glance

• Manufacturer: Siemens
• Part Number: BQ2B125
• Type: Thermal-magnetic molded case circuit breaker
• Amperage rating: 125 A
• Voltage rating: 240 V
• Number of poles: 2
• Mounting style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Designed for reliable performance in panelboards and loadcenters, the Siemens BQ2B125 helps you protect circuits with confidence. Whether upgrading an existing installation or outfitting a new panel, this 2-pole, bolt-on breaker delivers dedicated protection for your home or small-to-mid-size commercial electrical systems.