Square D LLA36400U53X - 400 A, 3-Pole Plug-In Circuit Breaker | AmpState

Meet the Square D LLA36400U53X—a 400 A, 3-pole plug-in molded case circuit breaker designed to deliver dependable branch circuit overcurrent and short-circuit protection in panelboards and loadcenters. Built for reliable performance in demanding environments, this unit is a precise fit for three-phase distribution systems where safety and uptime matter.

Key advantages at a glance

• Fast plug-in connection for quick installation and straightforward replacements, minimizing downtime during panel maintenance or upgrades.
• Thermal-magnetic trip unit provides stable, repeatable protection by handling both overload conditions (thermal) and short-circuit events (magnetic) with decisive action.
• 3-pole design ideal for three-phase applications, offering coordinated protection across all phases in your panelboard or loadcenter.
• OEM-compatible engineered to pair with matching Square D load centers and panelboards, ensuring consistent performance and ease of integration.
• Versatile installation footprint suited for residential, commercial, and light industrial applications where robust protection is essential.

What this means in real-world terms

• In a commercial office building, use the LLA36400U53X to protect main feeders and branch circuits from overloads and short circuits, helping prevent equipment damage and electrical fires.
• In a light-industrial setting, rely on its 400 A rating to safeguard motors, feeders, and distribution panels without frequent nuisance trips.
• During a retrofit or panel upgrade, this plug-in breaker simplifies replacement in compatible Square D systems, reducing install time and compatibility concerns.

How it works

The device combines a thermal element and magnetic trip to monitor current flow continuously. Under normal conditions, the breaker remains closed, allowing uninterrupted power. If a thermal overload develops, the thermal element gradually trips to prevent overheating. If a fault creates a sudden surge, the magnetic mechanism reacts quickly to interrupt current, protecting both conductors and connected equipment.

Technical snapshot

• Manufacturer: Square D
• Part Number: LLA36400U53X
• Type: Thermal-magnetic molded case circuit breaker
• Amperage Rating: 400 A
• Number of Poles: 3
• Mounting Style: Plug-in
• Application: Branch circuit overcurrent and short-circuit protection

For professionals prioritizing reliability and compatibility, the Square D LLA36400U53X represents a purpose-built solution that aligns with OEM panelboards and loadcenters. Choose it to ensure consistent protection across three-phase installations, streamline downtime when servicing panels, and maintain safer, code-compliant electrical distribution in residential, commercial, and light industrial environments.