The LJA36600U31XTB is part of the PowerPacT L-Frame family, delivering 600A for industrial applications. It utilizes a Micrologic 3.3 LI trip unit for accurate long-time and instantaneous protection. Featuring an I-Line design, this MCCB installs quickly into Square D I-Line panelboards and switchboards. It includes stud/tapped pad terminals. Rated 65kAIC at 480VAC, this electronic trip breaker ensures superior current-limiting performance and true RMS sensing.
What type of panelboards will accept the LJA36600U31XTB circuit breaker?
This breaker features an I-Line plug-in connection and is designed specifically for installation in Square D I-Line panelboards and switchboards. It will not fit in standard bolt-on or load center panels.
How is the LJA36600U31XTB physically mounted into the switchboard?
It utilizes Square D's I-Line mounting system. The line side of the breaker plugs directly onto the vertical bus stack in the panelboard, while the load side uses stud or tapped pad terminals for your outgoing wire connections.
What wire sizes are supported by the load side terminals on this 600A breaker?
The load side connections accept two 2/0 AWG to 500 kcmil aluminum or copper conductors per phase. The line side connects directly to the I-Line bus and does not require wiring.
What protection settings are provided by the LI electronic trip unit?
The LI designation means the trip unit includes adjustable Long-Time (L) and Instantaneous (I) functions. This allows panel builders to precisely coordinate the breaker's overload and short-circuit response with the rest of the electrical distribution system.
Can the LJA36600U31XTB be used on a 480V system with 50,000 amps of available fault current?
Yes. This breaker carries an interrupting rating of 65kAIC at 480VAC, which safely exceeds a 50kA available fault current requirement at that voltage.
Is the LJA36600U31XTB a direct replacement for older 600A L-frame I-Line breakers?
Yes, this PowerPacT L-frame breaker is the modern replacement for legacy Square D 600A I-Line breakers. You must verify that the 65kAIC at 480V rating and the LI trip functions meet your specific site requirements before installing.
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Shipping
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Parcel shipments with item value over $99 qualify for free economy shipping within the continental US. Please call to confirm special handling instructions. We do not charge a handling fee or require a minimum amount on any order. SuperBreakers does not ship on customer accounts.
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Reviews
Review summary
Customers rate this product 4.8 out of 5 based on 4 reviews.
Square D LJA36400U31X - 400A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
8/27/26
Great!
Quick delivery
JB
Jeffrey B.
Verified Buyer
Reviewing
Square D LJA36600U31X - 600A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
7/20/26
Purchased breaker - Great experience
We recently needed to purchase a specialty breaker for a large commercial project. Zach, our account manager sprung into action and really made this a white glove experience. From communication to speed I was impressed the entire process. Will definitely be using super breakers for our future breaker needs. Would 1500% recommend!
EV
Erik V.
Verified Buyer
Reviewing
Schneider Electric LJA36600U44X - 600A 3 Pole Molded Case Circuit Breaker
I recommend this product
Rated 5 out of 5 stars
6/11/26
Purchase was easy.
The part was as described. Packing was excellent.
Thank you for the quick ship!
KP
Kevin P.
Reviewing
Square D LJA36600U31X - 600A 3 Pole Molded Case Circuit Breaker