Integrating remote signaling capabilities, this 350-amp MCCB includes a factory-installed 1A/1B auxiliary switch for advanced monitoring. The unit-mount design fastens securely into Square D switchboards and motor control centers. Rated for 65kA at 480VAC, it utilizes thermal-magnetic LI protection. For modern replacements, the PowerPact MJL36350 paired with an S29450 auxiliary contact block serves as the manufacturer's recommended upgrade path for this legacy M-Frame component.
Switchboards, Motor Control Centers, Industrial Enclosures
Wire Gauge
(3) 3/0 AWG - 500 kcmil (Al/Cu)
Max Wire
500 kcmil
Min Wire
3/0 AWG
Protection and operation
Trip Technology
Thermal Magnetic
Trip Function Code
LI
Trip Function
Long-Time, Instantaneous
Trip Adjustability
Fixed Thermal, Adjustable Magnetic
Standards and features
Available Options
Shunt Trip, Undervoltage Release, Alarm Switch
Accessories
Auxiliary Switch (1A/1B), Lugs
Standards
CSA C22.2 No. 5, HACR, UL 489
Approval
CSA, UL
Temp Rating
40C
Construction Features
HACR Rated, High Interrupting Capacity, Non-Interchangeable Trip
Product FAQs
6 answers
What does the 1212 suffix indicate on the MHL363501212 catalog number?
The 1212 suffix signifies that the breaker comes with a factory-installed 1A/1B auxiliary switch, which provides remote signaling of the breaker's open or closed status.
What is the modern replacement for the legacy MHL363501212?
The MHL363501212 is a legacy M-Frame breaker. The manufacturer's recommended upgrade path for modern applications is the PowerPact M-Frame series, specifically the MJL36350 paired with an S29450 auxiliary contact block to match the factory-installed switch.
How do you adjust the trip settings on the MHL363501212?
This thermal-magnetic breaker features a fixed thermal element for long-time protection at 350 amps. However, the magnetic instantaneous trip is adjustable, allowing electricians to fine-tune short-circuit protection for selective coordination.
What type of mounting does the MHL363501212 require?
This is a unit-mount, feed-thru circuit breaker. It is designed to be bolted directly to the backpan of industrial enclosures, motor control centers, or switchboards, and does not plug into an I-Line bus.
What are the wire size requirements for the MHL363501212 lugs?
The standard mechanical lugs on this breaker accept up to three 3/0 AWG to 500 kcmil conductors per phase. They are rated for both aluminum and copper wiring.
Is the MHL363501212 suitable for direct current (DC) systems?
Yes, in addition to its AC ratings, this breaker is rated for 250VDC applications with a 14kA interrupting capacity.
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