Siemens LGB3B125B - 125 A, 600 V, 3-Pole Bolt-On Circuit Breaker | AmpState

Siemens LGB3B125B is a 3-pole, 125 A molded case circuit breaker engineered for reliable branch-circuit overcurrent and short-circuit protection in panelboards and load centers. Its bolt-on design delivers a secure, vibration-resistant connection to bus bars, while the thermal-magnetic trip unit provides stable, repeatable protection in demanding environments. Compatible with matching Siemens OEM load centers, this device is a practical, code‑compliant choice for residential, commercial, and light industrial electrical distribution.

Key Benefits

• Secure bolt-on mounting creates a rigid, vibration‑resistant connection to the bus, reducing movement and wear over time.
• Thermal-magnetic trip combines a thermal element for overload protection with a magnetic element for short-circuit events, delivering fast, predictable trips and minimizing nuisance activations.
• OEM-compatible designed to pair with Siemens load centers and panelboards for seamless integration, code compliance, and reliable performance.
• Three-pole configuration ideal for balanced three‑phase distribution in commercial and light industrial applications.
• 600 V rating supports a wide range of industrial and commercial electrical networks, ensuring solid protection for higher voltage systems.
• 125 A protection appropriate for feeder and branch-circuit protection in mid‑to‑large installations.

Technical Details

• Manufacturer: Siemens
• Part Number: LGB3B125B
• Type: Thermal-magnetic molded case circuit breaker (MCCB)
• Amperage Rating: 125 A
• Voltage Rating: 600 V
• Number of Poles: 3
• Mounting Style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Ideal Applications

• Residential, commercial, and light industrial panelboards and load centers requiring reliable 3‑phase protection.
• Upgrading aging or undersized MCCBs to ensure safer distribution for feeders and subpanels.
• New installations where a robust, code‑compliant bolt-on MCCB is preferred for long-term durability in vibration-prone environments.

Installation and Use Considerations

• Use with Siemens OEM panelboards and load centers to guarantee full electrical compatibility and protection coordination.
• Ensure correct mounting and secure connections to achieve the vibration resistance that the design promises.
• Follow Siemens installation guidelines for wiring, torque, and protection coordination to maximize performance and safety.
• Ideal for systems where fast short-circuit response is critical, as the magnetic trip helps interrupt fault currents promptly.