Siemens B125 - 25 A, 120 V, 1-Pole Bolt-On Circuit Breaker | AmpState

Meet the Siemens B125, a 25 A, 120 V, 1-pole bolt-on molded case circuit breaker engineered for dependable branch-circuit protection in panelboards and loadcenters. This compact, rugged device is built to stand up to everyday electrical demands while delivering precise, repeatable protection for your circuits.

What sets the B125 apart is its secure bolt-on mounting, which creates a rigid, vibration-resistant bus connection. That means fewer alignment issues, reduced wear over time, and a more consistent electrical path—even in environments with movement or vibration. Coupled with a thermal-magnetic trip unit, this breaker delivers stable overcurrent protection and immediate response to short circuits, helping prevent damage to wiring and connected equipment.

Key specifications

• Amperage rating: 25 A
• Voltage rating: 120 V
• Poles: 1
• Mounting style: Bolt-on
• Type: Thermal-magnetic molded case circuit breaker
• Part number: B125

Ideal applications and use cases

• Residential panelboards where a compact, reliable overcurrent device is needed for a dedicated branch circuit
• Commercial loadcenters requiring a robust bolt-on solution with dependable protection performance
• Light industrial panels where vibration resistance and consistent trip characteristics matter
• Replacement or upgrade in OEM-matched Siemens panels to maintain system compatibility and warranty integrity

Why choose the Siemens B125

• Reliability in motion: Bolt-on mounting provides a secure, vibration-resistant connection that stays tight over time, preserving a clean electrical path.
• Predictable protection: The thermal-magnetic trip unit offers stable, repeatable performance for both overloads and short circuits, reducing nuisance trips and safeguarding downstream wiring.
• OEM compatibility: Designed to pair with matching Siemens panels and loadcenters, ensuring seamless integration and ongoing system compatibility.
• Versatile coverage: Suitable for residential, commercial, and light industrial environments, making it a practical choice for a wide range of projects or replacements.

Whether you’re upgrading an existing panel, expanding a circuit, or stocking spare parts for service crews, the Siemens B125 delivers dependable protection with a straightforward bolt-on installation. Choose this 1-pole, 25 A breaker for a compact, durable solution that keeps electrical systems safe and compliant.