Square D | LJF36400U44X | Circuit Breaker | 400A | 3-Pole | 600V

Meet the Square D LJF36400U44X Circuit Breaker—a heavy-duty protection device built to meet the exacting needs of industrial and commercial electrical systems. With a 400A rating, 3-pole configuration, and a 600V operating capability, this breaker is engineered for demanding service feeders, retrofit projects, and replacement scenarios where precise specs matter.

Key specifications at a glance

• Amperage: 400A
• Poles: 3-Pole
• Voltage: 600V
• Part number: LJF36400U44X
• Best use: maintenance, retrofit, and replacement where exact specs are required
• Note: Confirm fit and ratings before ordering. The part number is the most reliable reference for compatibility.

Why this breaker stands out

Designed for reliability in high-demand environments, the Square D LJF36400U44X delivers precise tripping behavior and robust construction that electricians trust for critical power distributions. Its 3-pole configuration provides solid protection across all three phases, making it a practical choice for 600V systems found in commercial facilities, manufacturing floors, and data-center infrastructures.

Ideal applications

• Maintenance and repair of existing 600V distribution panels that require a 400A, 3-pole breaker
• Retrofit projects where exact specifications are required to maintain panel ratings and code compliance
• Replacement of failed breakers in industrial equipment and commercial electrical systems

Practical considerations and tips

To ensure a seamless fit and optimal performance, verify your panel’s catalog number and the required interrupting rating before purchasing. Use the part number LJF36400U44X as the primary reference to confirm compatibility with your Square D panel and its bus configuration. This approach helps minimize downtime and ensures you’re applying the correct protection for your circuit.

What to expect in use

Once installed, you’ll benefit from dependable overcurrent protection that supports safe operation of high-load circuits. This breaker is suitable for scenarios where precise current interruption at or above 400A is required and where a 600V rating aligns with the system specifications. For best results, pair with compatible Square D panel hardware and follow standard electrical safety practices during installation and maintenance.