Engineered for complex coordination, this 400A PowerPacT L-Frame breaker delivers reliable microprocessor-based protection for industrial facilities. It offers enhanced system selectivity. The robust I-Line connection system mounts into compatible Square D panelboards and switchboards. It provides a highly configurable replacement alternative for older LA36400 and LH36400 installations. A MicroLogic 3.
Shunt Trip, Auxiliary Switch, Undervoltage Release, Alarm Switch, Padlock Attachment, Motor Operator, Rotary Handle, Communication Module
Accessories
MicroLogic 3.3S Trip Unit, Lugs
Standards
CSA C22.2 No. 5, IEC 60947-2, NEMA AB 1, UL 489
Approval
CCC, CE, CSA, IEC, NOM, UL
Temp Rating
-25C to 70C
Construction Features
Current Limiting, HACR Rated, True RMS Sensing, 80% Rated
Product FAQs
8 answers
What type of panelboards accept the LLA36400U33X circuit breaker?
This breaker features an I-Line plug-in connection on the line side and is exclusively designed for installation in Square D I-Line panelboards and switchboards. It cannot be used in standard unit-mount or load center applications.
What does the U33X suffix mean in the LLA36400U33X catalog number?
The U33X suffix indicates the breaker is equipped with a Micrologic 3.3S electronic trip unit. This solid-state trip unit provides field-adjustable Long-Time, Short-Time, and Instantaneous (LSI) overcurrent protection.
Can the LLA36400U33X replace older LA or LH frame circuit breakers?
Yes, the PowerPacT L-Frame is the modern replacement for legacy Square D LA36400 and LH36400 I-Line breakers. While it fits the same I-Line bus, the LLA36400U33X upgrades the protection from traditional thermal-magnetic to an advanced electronic trip unit.
What is the difference between the line and load connections on the LLA36400U33X?
As an I-Line breaker, the line side features a plug-on jaw assembly that mounts directly onto the panelboard bus. The load side is equipped with mechanical lugs for terminating the outgoing wire conductors.
What wire sizes are compatible with the load lugs on this breaker?
The factory-installed load lugs accept two aluminum or copper conductors per phase, ranging from 2/0 AWG to 500 kcmil. Ensure proper torque specifications are followed during installation.
Does the Micrologic 3.3S trip unit on this breaker include ground fault protection?
No, the Micrologic 3.3S trip unit provides LSI (Long-Time, Short-Time, Instantaneous) protection only. It does not include equipment ground fault protection (LSIG).
Is the electronic trip unit on the LLA36400U33X interchangeable?
No, the Micrologic 3.3S trip unit is factory-sealed and non-interchangeable. The entire circuit breaker must be replaced if a different trip unit configuration is required.
Can this 3-pole breaker be used in a 2-pole application?
Yes, this 3-pole I-Line breaker can be utilized for 2-pole applications within a compatible panelboard. However, it will still occupy the physical space of three poles on the bus assembly.
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