Square D M9F42320 - Circuit Breaker | AmpState

Meet the Square D M9F42320 molded case circuit breaker—an efficient, dependable solution for safeguarding branch circuits in panelboards and load centers. Built around a thermal-magnetic trip unit, this breaker delivers stable, repeatable protection against overloads and short circuits, while keeping valuable panel space organized.

Why the M9F42320 stands out

• Space-efficient molded case design minimizes footprint in your panelboard, helping you maximize space for feeders, devices, and future expansion.
• Thermal-magnetic trip unit combines heat and magnetic mechanisms for precise, fast response to faults, reducing nuisance trips and improving overall electrical safety.
• OEM-compatible fit designed to work with matching Square D load centers and panelboards for straightforward replacement and reliable coordination with existing protection schemes.
• Versatile for multiple environments suitable for residential, commercial, and light industrial applications where dependable branch-circuit protection is critical.

What problems it solves

This molded case breaker delivers predictable protection where it matters most—preventing damage from overcurrent and short circuits while maintaining steady performance over time. Its compact design and reliable trip behavior help electricians and facility managers avoid panel swaps, reduce downtime, and keep electrical systems running smoothly in both new installations and retrofits.

Compatibility and use cases

• Designed to integrate with matching OEM Square D panelboards and load centers, ensuring proper fit, trip coordination, and electrical integrity.
• Ideal for retrofits where aging breakers are replaced with a modern, dependable solution that aligns with existing Square D infrastructure.
• Well-suited for residential service panels, commercial distribution boards, and light industrial equipment where reliable protection is essential.

Technical snapshot

• Manufacturer: Square D
• Part Number: M9F42320
• Type: Thermal-magnetic molded case circuit breaker
• Application: Branch circuit overcurrent and short-circuit protection

Choose the Square D M9F42320 when you need a compact, reliable circuit protection solution that integrates seamlessly with Square D panelboards and load centers, delivers consistent trip performance, and supports efficient panel space utilization in residential, commercial, and light industrial settings.