Siemens | KM3B400 | Circuit Breaker | 400A | 3-Pole | 600V | 50kA | Bolt-On

Meet the Siemens KM3B400 Circuit Breaker — a rugged 3-pole, 400A protection device built for bolt-on installation in compatible panels. Engineered for reliability in demanding environments, it handles up to 600V with a formidable 50kA interrupting rating, delivering decisive fault current protection that helps keep equipment and production lines up and running.

Key specifications at a glance

• Amperage: 400 A
• Poles: 3-Pole
• Voltage rating: 600 V
• Interrupting capacity: 50 kA
• Mounting: Bolt-On
• Part reference: KM3B400 (best compatibility reference)

Why choose the KM3B400 bolt-on breaker

• Secure, vibration-resistant mounting: The bolt-on design provides solid mechanical retention in environments with equipment movement or vibration, reducing the risk of loose connections over time.
• Three-phase protection with synchronized trip: A true 3-pole configuration ensures all phases trip together, safeguarding motors and three-phase loads from imbalance or single-phase faults.
• High fault-current resilience: With a 50kA interrupting rating, this breaker is ready to interrupt substantial fault currents, helping minimize equipment damage and downtime.
• Industrial-grade voltage handling: Rated for up to 600V, it fits a wide range of commercial and light industrial distribution systems and motor feeders.
• Clear compatibility guidance: The KM3B400 part number is the most reliable reference for matching panels and bus configurations — always verify fit and ratings before ordering.

Ideal applications and use cases

• Retrofits and replacements in Siemens-compatible panels where a 400 A, 3-pole, 600 V bolt-on breaker is required.
• Motor feeders and main disconnect sections in industrial facilities, manufacturing lines, and commercial buildings with three-phase loads.
• Maintenance upgrades that demand solid mechanical retention and reliable fault protection in panels exposed to vibration or continuous cycling.

Practical guidance for installation and safety

• Always confirm fit and ratings against your panel model before ordering; the KM3B400 reference is your best compatibility indicator.
• Power down the panel and follow lockout/tagout procedures before mounting or replacing the breaker.
• Ensure the mounting surface and bus connections align with the bolt pattern and torque specifications recommended for bolt-on installations.
• Inspect conductors and terminations for clean contact surfaces to maintain optimal electrical performance and reliability.

The Siemens KM3B400 is more than a protective device—it’s a strategic investment in uptime, safety, and controllable power for demanding electrical systems. If your panel or project requires a 400A, 3-pole, bolt-on breaker with a 600V rating and 50kA interrupting capacity, this KM3B400 unit is designed to meet those exacting specifications with precision.