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Square D 999350 Molded Case Circuit Breaker
- 50A
- 3 Pole
- Bolt-On
Square D
999350
Molded Case Circuit Breaker
Brand
Square D
SKU
999350
Quantity
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Square D 999350 - 50A 3 Pole Molded Case Circuit Breaker
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Description
Part of the legacy 999 series, the Square D 999350 is a 3-pole molded case circuit breaker rated for 50 amps. It provides essential thermal-magnetic overcurrent protection for commercial and industrial facilities maintaining older infrastructure. This Type ML-1 breaker features a bolt-on mounting style, allowing it to install securely into Square D ML panelboards and motor control centers. It delivers a 10kAIC interrupting rating at 600VAC with fixed long-time and instantaneous functions.Specifications
| Brand | Square D |
|---|---|
| Part Number | 999350-R |
| Series | 999 |
| Amperage | 50A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 600VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 600VAC |
| Terminal Type | Lugs |
|---|---|
| For Use With | Square D ML Panelboards, Square D Motor Control Centers |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed Thermal, Fixed Magnetic |
| Accessories | Load Side Lugs Included |
|---|---|
| Standards | UL 489 |
| Approval | UL |
| Temp Rating | 40°C |
| Construction Features | Type ML-1, Obsolete/Legacy |
Product FAQs
9 answersCan I use the 999350 breaker in modern Square D I-Line or QO panels?
No. The 999350 is a legacy 99 Frame breaker specifically designed for older Square D ML panelboards and Motor Control Centers. It will not fit in modern I-Line or QO panels.
How does the Square D 999350 mount into a panelboard?
This Type ML-1 breaker uses a bolt-on mounting configuration to secure directly to the bus structure within compatible Square D ML panelboards and MCC buckets.
Is the Square D 999350 still actively manufactured?
No, the 999350 is an obsolete, legacy Type ML-1 breaker. It is typically sourced as a replacement part for maintaining existing older infrastructure rather than for new installations.
Are the trip settings adjustable on the Square D 999350?
No, this breaker features fixed thermal and fixed magnetic trip elements. The long-time and instantaneous (LI) protection functions cannot be adjusted in the field.
What type of wire connections does the 999350 breaker support?
It comes equipped with standard lugs for terminating your conductors. Ensure you use the proper torque specifications when securing the wiring to maintain a safe connection.
What frame family does the 999350 circuit breaker belong to?
It belongs to the legacy Square D 99 Frame family, which dictates its physical dimensions and mounting footprint for ML panelboards.
What does the ML-1 designation mean for the 999350 breaker?
Type ML-1 refers to the specific legacy physical frame and mounting configuration used by Square D for this line of 99 Frame breakers, ensuring it aligns correctly with older ML series busbars.
Is the 999350 suitable for motor control applications?
Yes, it is commonly used as a feeder breaker in legacy Square D Motor Control Centers (MCC), providing reliable 50A overcurrent protection for motor circuits.
What precautions should be taken before installing the 999350 breaker?
Always verify that power to the ML panelboard or motor control center is completely de-energized and locked out before attempting to bolt on or remove the breaker.
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