Square D LJA36400U54X - 400 A, 3-Pole Plug-In Circuit Breaker | AmpState

The Square D LJA36400U54X is a 400 A, 3-pole plug-in molded case circuit breaker engineered to shield your most demanding branch circuits in panelboards and loadcenters. Designed for rapid installation and dependable protection, this unit delivers reliable thermal-magnetic trimming for residential, commercial, and light industrial environments.

Key benefits that matter in real-world setups

• Fast plug-in connection enables quick installation and effortless replacement, reducing panel downtime during service or upgrades.
• Thermal-magnetic trip unit provides stable, repeatable protection against both overloads and short circuits, helping minimize nuisance trips while safeguarding valuable equipment.
• OEM-compatible compatibility coordinates with matching Square D loadcenters and panelboards for a consistent fit and predictable trip performance.
• Three-pole design delivers balanced protection across three phases, essential for equipment and motors in commercial and light industrial applications.
• High current capability with a 400 A rating, suitable for large branch circuits, feeders, and main distribution paths within compatible panels.
• Plug-in mounting simplifies installation, retrofit, and maintenance in existing Square D systems without complex wiring changes.

Product details at a glance

• Manufacturer: Square D
• Part Number: LJA36400U54X
• 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

Ideal usage scenarios

• Upgrading or replacing breakers in existing Square D panelboards and loadcenters where a 400 A, 3-pole solution is required
• Providing robust protection for large-capacity feeders feeding critical equipment in commercial spaces
• Protecting three-phase motor circuits and heavy loads in light industrial environments
• New installations that demand quick, reliable plug-in protection with OEM-wide compatibility

Why this breaker stands out

Compared to other mounting approaches, the plug-in design of the LJA36400U54X minimizes configuration complexity and service interruption. The molded case construction offers durable insulation and reliable fault isolation, while the thermal-magnetic trip system ensures precise, predictable responses to overloads and short circuits. If you need a dependable, high-capacity solution that cleanly integrates with existing Square D panels, this 400 A, 3-pole unit is purpose-built to keep systems online and protected.

Compatible, efficient, and purpose-driven—the Square D LJA36400U54X is engineered to deliver consistent performance where it matters most: in the protection of your most valuable electrical infrastructure.