Square D LLL36400U33X - 400 A, 3-Pole Circuit Breaker | AmpState

The Square D LLL36400U33X is a 400 A, 3-pole molded case circuit breaker built to shield panelboards and load centers from overcurrent and short-circuit faults. With this unit in your electrical system, you gain reliable, rapid interruption to protect vital circuits and connected equipment.

Its compact molded-case design maximizes panel space, allowing you to fit high-capacity protection without crowding other devices. The thermal-magnetic trip unit delivers stable, repeatable protection across varying loads and temperatures, reducing nuisance trips while maintaining dependable circuit safety.

Designed for seamless compatibility with matching OEM Square D load centers and panelboards, this breaker installs cleanly in compatible assemblies, simplifying upgrades or main-breaker replacements in existing panels. It’s suitable for residential, commercial, and light industrial applications requiring robust 400 A protection for feeders and branch circuits.

• Amperage rating: 400 A
• Poles: 3
• Type: Thermal-magnetic molded case circuit breaker
• Application: Branch circuit overcurrent and short-circuit protection
• Manufacturer: Square D
• Part number: LLL36400U33X

Use cases in real-world setups include serving as a main feeder breaker in large service panels, protecting heavy feeders in commercial electrical rooms, or acting as a main-protection device in substantial residential subpanels. Its combination of high current capability, compact footprint, and compatibility with Square D load centers makes it a practical choice when you need dependable protection without sacrificing panel room.

For installation, ensure you’re pairing this breaker with a compatible OEM panelboard or load center and follow local electrical codes. The LLL36400U33X delivers clear, predictable performance when properly integrated into your protection scheme, helping you maintain safe, compliant, and efficient electrical distribution.