Siemens NJG3B400L 400A 3P 480V Circuit Breaker | AmpState

Siemens NJG3B400L 400A 3P 480V Circuit Breaker from AmpState delivers reliable, heavy-duty protection for industrial and commercial electrical distributions. Built for panelboards, load centers, and wide-ranging distribution applications, this Siemens breaker is a trusted choice when uptime and safety matter as much as performance.

Why this circuit breaker stands out

• High-capacity, three-phase protection — 400 A rating across three poles is ideal for demanding three-phase circuits, feeders, and equipment racks in commercial facilities, manufacturing lines, and data-center infrastructures.
• 400A, 3P, 480V capability — Designed to integrate with standard 480V distribution schemes, ensuring seamless operation in mid-to-large scale electrical environments.
• Maintains compatibility through parts-based maintenance — This NJG3B400L part number is a dependable choice when retrofit work or service planning requires keeping the same component identity for easy stocking and replacement.
• Proven Siemens reliability — Backed by Siemens engineering and manufacturing standards, delivering consistent performance in protective applications across panelboards and distribution boards.
• Available from AmpState — A trusted source for genuine Siemens breakers, with support to help you confirm fit and ensure you’re selecting the right part for your panel.

Ideal use cases

Use the NJG3B400L for aggressive protection in:

• Panelboards and load centers powering large commercial spaces, workshops, and data centers.
• Industrial distribution where three-phase circuits require solid overcurrent protection at 480V systems.
• retrofit projects where maintaining a consistent part number simplifies procurement, documentation, and maintenance calendars.

What to expect in practice

Beyond the basic specs, this circuit breaker supports practical, real-world needs:

• Operational confidence from a device designed for continuous service in demanding environments.
• streamlined maintenance planning by keeping the part number stable across replacements, reducing confusion during outages or scheduled downtime.
• Clear sourcing path through AmpState, with guidance available to verify compatibility before purchase.

Key technical specifications

• Manufacturer: Siemens
• Part number: NJG3B400L
• Amperage: 400 A
• Poles: 3
• Voltage: 480 V
• Applications: Circuit protection for panelboards, load centers, and electrical distribution

Need help with fit?

If you’re unsure about compatibility or how the NJG3B400L will integrate with your specific Siemens panels, we’re here to help. Message us and we’ll assist you in confirming fit and ensuring you’ve chosen the right part for your system.