Siemens FXD63B125L - 125 A, 600 V, 3-Pole Bolt-On Circuit Breaker | AmpState

Siemens FXD63B125L is a robust 125 A, 600 V, 3-pole bolt-on molded case circuit breaker designed to deliver dependable branch circuit overcurrent and short-circuit protection inside panelboards and load centers. Built for environments where vibration and reliability matter, this unit combines precise protection with a straightforward, durable installation.

• Secure bolt-on mounting delivers a rigid, vibration-resistant bus connection, helping maintain a steady electrical path even in busy equipment rooms.
• Thermal-magnetic trip unit provides stable, repeatable protection by responding to both gradual overcurrents and sudden faults, reducing nuisance trips and improving protection coordination.
• OEM-compatible design matches Siemens load centers and panelboards, making replacements and upgrades smoother without sacrificing performance.
• Versatile across applications ideal for residential, commercial, and light industrial panels where reliable protection is essential for safety and uptime.

Key specifications at a glance

• Amperage rating: 125 A
• Voltage rating: 600 V
• Number of poles: 3
• Mounting style: Bolt-on
• Type: Thermal-magnetic molded case circuit breaker
• Part number: FXD63B125L
• Application: Branch circuit overcurrent and short-circuit protection

What this means in real-world use: this breaker serves as a reliable line of defense for individual branches within a panelboard, quickly isolating faulted circuits to protect wiring, devices, and downstream equipment. The bolt-on design ensures a solid, long-lasting connection to the panel’s bus, while the thermal-magnetic trip unit delivers protective action tailored to both everyday loads and fault conditions.

Ideal use scenarios include upgrading or replacing aging protection in residential service panels, equipping commercial electrical rooms with dependable branch protection, or provisioning lightweight industrial installations where compact, rugged protection is required. Pair this 3-pole breaker with compatible Siemens panelboards to maintain consistent protection schemes and easy maintenance.

Practical installation and usage notes: ensure your enclosure supports bolt-on molded case breakers and that the panelboard is a compatible Siemens OEM model. Follow standard electrical best practices for wiring and secure attachment to the bus, then rely on the thermal-magnetic trip to deliver accurate, repeatable protection aligned with your system’s design and load profiles.