Siemens B245 - 45 A, 240 V, 2-Pole Bolt-On Circuit Breaker | AmpState

Meet the Siemens B245—an exacting 2-pole, 45A, 240V bolt-on molded case circuit breaker designed to safeguard your panelboards and load centers. Built for dependable branch circuit overcurrent and short-circuit protection, this unit blends robust hardware with precise protection logic to keep electrical systems safe and interruption-free.

Why the Siemens B245 stands out

• Secure bolt-on mounting: A rigid, vibration-resistant bus connection minimizes looseness and ensures consistent electrical contact, even in panels that experience vibration or movement.
• Thermal-magnetic trip unit: Combines a thermal element for gradual overload protection with a magnetic trip for rapid response to short circuits, delivering stable, repeatable protection performance.
• OEM panel compatibility: Specifically designed to work with matching Siemens OEM load centers and panelboards, helping maintain proper fitment and trip coordination.
• Versatile 2-pole, 240V protection: Ideal for residential, commercial, and light industrial applications where a reliable 45A, 240V circuit protection is required.

Technical specifications at a glance

• Manufacturer: Siemens
• Part number: B245
• Type: Thermal-magnetic molded case circuit breaker
• Amperage rating: 45A
• Voltage rating: 240V
• Number of poles: 2
• Mounting style: Bolt-on
• Application: Branch circuit overcurrent and short-circuit protection

Ideal use cases

• Feeding 240V branch circuits in residential panels, such as ranges, water heaters, or large appliances that require 45A protection.
• Installing subpanels in light commercial settings where secure bolt-on mounting and reliable surge/short-circuit protection are critical.
• Replacing aging breakers in panelboards to restore precise trip characteristics and durable performance in environments with periodic vibration.
• Upgrading or maintaining OEM-compatible panels to ensure proper bus connection, fit, and coordination with other Siemens breakers.

How it helps your electrical system

The B245 provides a balanced combination of protection and reliability. The thermal-magnetic design means the device responds appropriately to both gradual overloads and sudden faults, reducing wear on conductors and equipment. Bolt-on mounting minimizes connection fatigue and vibration-induced looseness, preserving contact quality over time. When paired with compatible Siemens panelboards, it helps maintain consistent trip curves and safe, predictable operation across your electrical system.

Practical tips for selection and installation

• Confirm panel compatibility: Choose the B245 when your OEM panelboard specification calls for a 2-pole, 45A, 240V bolt-on breaker from Siemens.
• Match with load requirements: Plan for continuous loads at or below 80% of the 45A rating to minimize nuisance tripping and extend circuit life (e.g., continuous loads under 36A).
• Consider panel layout and wiring: Bolt-on breakers require secure mounting and clean bus connections—reserve space in the panel for proper alignment and routing.
• Coordinate protection: Ensure the new breaker’s trip characteristics align with adjacent breakers to maintain system coordination and selective tripping behavior.

Whether you’re stocking a repair bay for Siemens panelboards or outfitting a new installation, the Siemens B245 2-pole bolt-on circuit breaker delivers precise, dependable protection for 240V circuits. Trust AmpState to provide authentic, OEM-compatible components that integrate smoothly with your existing electrical infrastructure.