Square D MJA36300 - 300 A, 600 V, 3-Pole Plug-In Circuit Breaker | AmpState

Engineered for dependable branch circuit protection, the Square D MJA36300 is a 300A, 600V, three-pole plug-in molded case circuit breaker designed to drop into compatible panelboards and load centers with ease. Built to perform in demanding commercial and light industrial environments, it delivers fast installation, reliable protection, and long service life where it truly matters—the safety of your electrical distribution.

Key advantages

• Plug-in convenience: Fast plug-in connection enables quick installation and rapid replacement when maintenance or upgrades are needed, minimizing downtime.
• Thermal-magnetic protection: A thermal-magnetic trip unit provides stable, repeatable overcurrent and short-circuit protection, helping to prevent nuisance trips while safeguarding wiring and equipment.
• OEM-compatible: Carefully designed to be fully compatible with matching Square D OEM load centers and panelboards for a seamless fit and coordinated protection strategy.
• Versatile power handling: With a 600V rating and a 3-pole configuration, it supports three-phase circuits commonly found in commercial and light industrial applications.

Applications and use cases

Ideal for panelboard upgrades, new installations, or field replacements in facilities where reliability is key. Suitable for protecting feeders and branch circuits serving HVAC equipment, lighting and power distribution, pumps, conveyors, and other 3‑phase loads in small to mid-size commercial and light industrial settings. The plug-in design simplifies serviceability in crowded panels, reducing project timelines and downtime.

Why choose the MJA36300

• Reliable protection for critical circuits with a focus on stable trip performance and quick restoration after a fault.
• Eliminates compatibility guesswork by aligning with matching OEM panelboards and load centers.
• Designed to withstand the rigors of everyday electrical distribution in commercial and light industrial environments.

Technical snapshot

• Manufacturer: Square D
• Part Number: MJA36300
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 300A
• Voltage Rating: 600V
• Number of Poles: 3
• Mounting Style: Plug-in
• Application: Branch circuit overcurrent and short-circuit protection

When you’re upgrading a panel or provisioning a new commercial or light industrial installation, the Square D MJA36300 delivers a plug‑in, three‑pole solution that combines rapid serviceability with dependable protection. It’s the practical, compatible choice for safeguarding your electrical distribution while keeping downtime to a minimum.