Siemens JD63B400 - 300 A, 400 V, 3-Pole Bolt-On Circuit Breaker | AmpState

Siemens JD63B400 is a rugged 300A, 400V, 3-pole bolt-on molded case circuit breaker designed to protect your branch circuits with precision in panelboards and loadcenters. Built for dependable overcurrent and short-circuit protection, this breaker keeps critical systems safe in residential, commercial, and light industrial settings.

Why this bolt-on Siemens breaker stands out

• Secure bolt-on mounting delivers a rigid, vibration-resistant bus connection, maintaining consistent electrical contact even in environments with machinery or movement.
• Thermal-magnetic trip unit provides stable, repeatable protection across a range of temperatures and loading conditions, combining long-term reliability with fast fault response.
• 3-pole design ensures simultaneous disconnection of all three phases, enhancing safety and protection for balanced 3-phase loads.
• OEM compatibility compatible with matching Siemens OEM loadcenters and panelboards, simplifying replacement and upgrade projects.

Ideal use cases

Designed for main feeder protection and branch circuit safety, the JD63B400 excels in:

• New panelboard installations where a robust 3-pole, bolt-on breaker is required
• Retrofits and service upgrades in residential, commercial, and light industrial environments
• Control and distribution panels needing reliable overcurrent and short-circuit protection

What it protects and how it benefits you

The JD63B400 safeguards your electrical system by detecting overloads and short circuits across all three phases, then tripping predictably to prevent damage, nuisance outages, and dangerous hot spots. A thermal element handles gradual overloads, while the magnetic element responds to high fault currents for rapid isolation of the circuit. With this combination, you get dependable protection that remains consistent despite varying loads and ambient temperatures.

Key specifications

• Manufacturer: Siemens
• Part number: JD63B400
• Amperage rating: 300 A
• Voltage rating: 400 V
• Number of poles: 3
• Mounting style: Bolt-on
• Type: Thermal-magnetic molded case circuit breaker
• Applications: Branch circuit overcurrent and short-circuit protection

Practical tips for installation and operation

• Ensure your panelboard or loadcenter supports bolt-on breakers to maximize compatibility and performance.
• Verify alignment and clean connections during bolt-on mounting to maintain the vibration resistance and secure bus contact.
• Use in applications where stable, predictable trip characteristics are important, such as systems with variable loads or in environments with temperature fluctuations.
• Keep spare JD63B400 units on hand for quick replacements in service upgrades or panel refurbishments.

Whether upgrading an existing panel or installing a new, reliable protection solution, the Siemens JD63B400 3-pole bolt-on molded case circuit breaker delivers robust, dependable performance for residential, commercial, and light industrial electrical designs.