Square D LJL36400U44X - 400 A, 3-Pole Circuit Breaker | AmpState

The Square D LJL36400U44X is a 400A, 3-pole molded case circuit breaker designed to deliver dependable branch circuit overcurrent and short-circuit protection in panelboards and load centers. Built to fit into OEM systems, this breaker helps protect electrical infrastructure with precision and reliability.

• Amperage and Poles: 400A rating with 3 poles for multi-branch protection and streamlined bus bar integration.
• Molded case design: Compact footprint that maximizes panel space while maintaining robust protection.
• Thermal-magnetic trip unit: Delivers stable, repeatable protection by combining overload sensing with instantaneous short-circuit interruption.
• OEM compatibility: Engineered to be compatible with matching Square D load centers and panelboards, supporting straightforward retrofits and new builds.
• Applications: Suitable for residential, commercial, and light industrial environments where reliable branch circuit protection is essential.
• Specifications at a glance: Type — Thermal-magnetic molded case circuit breaker; Manufacturer — Square D; Part Number — LJL36400U44X; Application — Branch circuit overcurrent and short-circuit protection.

Why this Square D breaker stands out

In electrical panels where space is at a premium, the LJL36400U44X’s compact molded case design helps you maximize usable panel area without sacrificing protection. The thermal-magnetic trip mechanism provides balanced protection across varying loads and conditions, reducing nuisance trips while ensuring fast response to dangerous faults. When you pair this unit with compatible OEM load centers and panelboards, you get seamless electrical coordination, dependable performance, and a streamlined maintenance path for both new installations and upgrades.

Ideal use scenarios

• New construction: Installing a dedicated 400A 3-pole main or feeder in commercial panelboards.
• Panel retrofit: Upgrading or replacing a failed breaker in existing Square D systems to maintain compatibility and protection standards.
• Industrial light-duty applications: Protective device for feeder circuits supplying motors, transformers, and distribution loads within safe, code-compliant limits.
• Residential-commercial transitions: Systems that require a robust, high-capacity protection solution within centralized distribution panels.

Choose the Square D LJL36400U44X when you need a trusted, high-capacity, OEM-compatible breaker that preserves panel space and delivers reliable protection for critical electrical infrastructure.