Siemens B120 - 20 A, 120 V, 1-Pole Bolt-On Circuit Breaker | AmpState

The Siemens B120 is a compact, reliable solution for protecting individual branch circuits in residential, commercial, and light industrial panelboards. At 20 amps and 120 volts, this 1-pole, bolt-on molded case circuit breaker delivers dependable overcurrent and short‑circuit protection where it matters most.

Why choose the Siemens B120 20A 1-Pole Bolt-On Breaker? Its bolt-on mounting creates a rigid, vibration‑resistant connection to the bus, helping to maintain a consistent electrical pathway even in environments with everyday movement or vibration. The thermal‑magnetic trip unit provides stable, repeatable protection across a range of temperatures and conditions, ensuring the same trip behavior whether it’s hot or cool, quiet or busy load conditions. Designed to work alongside matching OEM load centers and panelboards, it offers a seamless, reliable replacement or upgrade within existing Siemens systems.

Key benefits at a glance

• Secure bolt-on mounting ensures a solid, vibration-resistant connection to the bus for long‑lasting performance.
• Thermal-magnetic trip delivers consistent protection against both overcurrent and short circuits, reducing nuisance trips and promoting safer operation.
• OEM-compatible fit guarantees reliable integration with Siemens load centers and panelboards’ design, layout, and labeling.
• Versatile application ideal for residential panels, small commercial setups, and light industrial circuits needing dependable single‑pole protection.

Technical snapshot

• Manufacturer: Siemens
• Part number: B120
• Type: Thermal-magnetic molded case circuit breaker
• Amperage rating: 20A
• Voltage rating: 120V
• Number of poles: 1
• Mounting style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Who is this for? Homeowners upgrading an older panel, electricians stocking a reliable go‑to for common 120V branch circuits, property managers maintaining multi‑unit buildings, and small business owners needing compliant, easy-to-install protection for lighting, outlets, and other 120V loads.

Practical tips — When replacing or adding protection, pair the B120 with a compatible Siemens load center to ensure consistent performance, clear labeling, and smooth operation during inspections. For best results, follow standard installation practices for bolt-on breakers and verify that the panel’s bus connections are clean and free of corrosion before mounting.