Square D HJA36150U31X Circuit Breaker | 150A 3-Pole 600V I-Line Plug-In

Square D HJA36150U31X — 150 Amp 3-Pole I-Line Molded Case Circuit Breaker

The Square D HJA36150U31X is a heavy-duty, 3-pole molded case circuit breaker engineered for demanding industrial and commercial power distribution applications. Rated at 150 Amps and 600/690V AC, this breaker features the proven I-Line plug-in connection system for fast, secure installation in compatible Square D I-Line panelboards — with no wiring required on the line side.

With a solid-state trip unit offering Long-Time (L) and Instantaneous (I) trip functions, the HJA36150U31X delivers precise, reliable overcurrent protection for motors, feeders, and large electrical loads across industrial environments.

Key Specifications

• Part Number: HJA36150U31X
• Manufacturer: Square D (Schneider Electric)
• Ampere Rating: 150A
• Number of Poles: 3-Pole
• Voltage Rating: 600/690V AC
• Connection Type: I-Line Plug-In
• Trip Type: Solid State — LI (Long-Time / Instantaneous)
• Interrupting Capacity:
  • 100 kAIC @ 240V AC
  • 65 kAIC @ 480V AC
  • 25 kAIC @ 600V AC
• Frame: HJ Frame
• Breaker Type: Molded Case Circuit Breaker (MCCB)
• Condition: New

Why Choose the Square D HJA36150U31X?

I-Line Plug-In Technology

The I-Line connection system allows the breaker to plug directly into the bus of an I-Line panelboard or switchboard — eliminating line-side wiring, reducing installation time, and improving system reliability. This makes it ideal for facilities that require frequent circuit reconfigurations or fast breaker replacement.

High Interrupting Capacity

With up to 100kAIC at 240V, this breaker is built to safely interrupt fault currents in high-energy distribution systems — protecting equipment, personnel, and infrastructure from arc flash and short-circuit damage.

Solid-State Precision

Unlike thermal-magnetic designs, the solid-state LI trip unit provides consistent and adjustable protection thresholds — reducing nuisance trips while maintaining tight overcurrent coordination across complex power systems.

Versatile Industrial Applications

The HJA36150U31X is suited for use in:

• Industrial manufacturing facilities
• Commercial buildings and data centers
• Motor control centers (MCCs)
• Electrical switchgear and distribution panels
• Oil & gas, utilities, and heavy industry

Frequently Asked Questions

What does HJA36150U31X mean?

The part number breaks down as follows: HJ = HJ frame class, A = I-Line plug-in, 3 = 3 poles, 6 = 600V, 150 = 150 Amp rating, U31X = solid-state LI trip unit configuration.

Is this breaker compatible with Square D I-Line panelboards?

Yes. The HJA36150U31X is designed specifically for use with Square D I-Line-style panelboards and switchboards that accept HJ frame plug-in breakers.

What is the difference between LI and LSI trip functions?

LI (Long-Time / Instantaneous) provides two zones of protection: sustained overload (long-time) and immediate response to high short-circuit currents (instantaneous). LSI adds a Short-Time delay zone for better coordination in cascaded systems.

Can this breaker be used as a motor disconnect?

Yes, when properly sized and applied per NEC requirements, a 150A molded case circuit breaker can serve as both overcurrent protection and disconnect means for large motor feeders.

What is the warranty or return policy?

Please contact our team directly for warranty details and return eligibility. All products are inspected before shipment.

Alpha Brokers & Controls specializes in new, surplus, and hard-to-find electrical components from top manufacturers like Square D (Schneider Electric). Need help finding a compatible breaker or panelboard? Contact our team for expert support.