Siemens / Murray MQJ2125 Molded Case Circuit Breaker
- 125A
- 2 Pole
- Unit Mount
Quantity
Siemens / Murray MQJ2125 - 125A 2 Pole Molded Case Circuit Breaker
New
Quantity
Description
Built to handle demanding electrical loads, this 125-amp QJ-frame breaker provides fixed long-time and instantaneous protection for commercial applications. It fastens into older Siemens and Murray metering equipment, offering a precise hardware match for aging infrastructure. With a 10kAIC capacity at 240VAC and HACR certification, this unit serves as the original counterpart to the newer QJ22B125, allowing contractors to service existing panels without extensive retrofits.Specifications
| Brand | Siemens / Murray |
|---|---|
| Series | MQJ |
| Amperage | 125A |
| Poles | 2 |
| Mounting Style | Unit Mount |
| Voltage | 240VAC |
| Phase | 1 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | MP |
|---|---|
| Terminal Type | Lugs |
| For Use With | Murray and Siemens Load Centers, Metering Equipment |
| Wire Gauge | 6 AWG - 300 kcmil (Cu), 4 AWG - 300 kcmil (Al) |
| Max Wire | 300 kcmil |
| Min Wire | 6 AWG (Cu), 4 AWG (Al) |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed Thermal, Fixed Magnetic |
| Available Options | Shunt Trip, Auxiliary Switch, Alarm Switch, Undervoltage Release, Padlock Attachment |
|---|---|
| Accessories | Load Side Lugs |
| Standards | CSA C22.2 No. 5, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Non-Interchangeable Trip, Common Trip |
Product FAQs
7 answersWhat load centers and equipment are compatible with the MQJ2125?
This breaker is designed for use in Murray and Siemens load centers, as well as compatible metering equipment that accepts QJ or QR frame bolt-on breakers.
Is the Murray MQJ2125 interchangeable with Siemens breakers?
Yes, Siemens acquired Murray, and their load centers often share compatibility. The Siemens QJ2125 is the direct equivalent to the Murray MQJ2125. Always verify your panel labeling for approved replacement types.
Can the MQJ2125 be used in a 3-phase system?
No, the MQJ2125 is a 2-pole breaker designed for 1-phase, 120/240VAC applications. It is not intended for 3-phase systems.
What type of trip functions does the MQJ2125 feature?
It features a thermal-magnetic trip unit with fixed long-time and instantaneous (LI) trip functions to protect against overloads and short circuits.
Does this breaker plug in or bolt on to the busbar?
The MQJ2125 is a unit-mount, bolt-on circuit breaker. It requires a bolted connection to the busbar and is not compatible with standard plug-on load centers.
Is the MQJ2125 suitable for high fault current applications?
This breaker has a standard interrupting rating of 10kAIC at 240V. If your system requires a higher interrupting capacity, you will need a different breaker model rated for those specific fault levels.
What safety precautions should be taken when installing the MQJ2125?
Always de-energize the panel or metering equipment before installation. Verify that the power is completely off using a reliable voltage tester, and ensure the bolted connections are properly torqued to prevent arcing or overheating.
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