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Square D KA36125-1021 Molded Case Circuit Breaker
- 125A
- 3 Pole
- I-Line
Square D
KA36125-1021
Molded Case Circuit Breaker
Brand
Square D
SKU
KA36125-1021
Quantity
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Square D KA36125-1021 - 125A 3 Pole Molded Case Circuit Breaker
Re-Certified
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Square D KA36125-1021 - 125A 3 Pole Molded Case Circuit Breaker
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| Brand | Square D |
|---|---|
| Part Number | KA36125-1021 |
| Series | KA |
| Amperage | 125A |
| Poles | 3 |
| Mounting Style | I-Line |
| Voltage | 240VAC, 480VAC, 600VAC, 250VDC |
| Phase | 3 |
| AIC Rating | 42kA @ 240VAC, 25kA @ 480VAC, 22kA @ 600VAC, 10kA @ 250VDC |
| Frame Type | KA |
|---|---|
| Terminal Type | Lugs |
| For Use With | Square D I-Line Panelboards and Switchboards |
| Wire Gauge | 4 AWG - 350 kcmil (Al/Cu) |
| Max Wire | 350 kcmil |
| Min Wire | 4 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed Thermal, Adjustable Magnetic |
| Available Options | Auxiliary Switch, Alarm Switch, Undervoltage Release |
|---|---|
| Accessories | Shunt Trip (120-240VAC), Load Side Lugs |
| Standards | CSA C22.2 No. 5, HACR, IEC 60947-2, NEMA AB 1, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Visual Trip Indicator |
Quantity
Square D KA36125-1021 - 125A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
| Brand | Square D |
|---|---|
| Part Number | KA36125-1021-R |
| Series | KA |
| Amperage | 125A |
| Poles | 3 |
| Mounting Style | I-Line |
| Voltage | 240VAC, 480VAC, 600VAC, 250VDC |
| Phase | 3 |
| AIC Rating | 42kA @ 240VAC, 25kA @ 480VAC, 22kA @ 600VAC, 10kA @ 250VDC |
| Frame Type | KA |
|---|---|
| Terminal Type | Lugs |
| For Use With | Square D I-Line Panelboards and Switchboards |
| Wire Gauge | 4 AWG - 350 kcmil (Al/Cu) |
| Max Wire | 350 kcmil |
| Min Wire | 4 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed Thermal, Adjustable Magnetic |
| Available Options | Auxiliary Switch, Alarm Switch, Undervoltage Release |
|---|---|
| Accessories | Shunt Trip (120-240VAC), Load Side Lugs |
| Standards | CSA C22.2 No. 5, HACR, IEC 60947-2, NEMA AB 1, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Visual Trip Indicator |
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Description
The KA36125-1021 is a 3-pole, 125A MCCB from Square D's legacy K-Frame lineup, built for commercial and industrial power distribution. Featuring an I-Line mounting style, it installs into Square D I-Line panelboards and switchboards. This legacy breaker is replaced by the PowerPact HGA36125SA. This model includes a factory-installed 120-240VAC shunt trip for remote disconnects. It delivers 42kAIC at 240VAC and features an adjustable magnetic trip.Specifications
| Brand | Square D |
|---|---|
| Part Number | KA36125-1021-R |
| Series | KA |
| Amperage | 125A |
| Poles | 3 |
| Mounting Style | I-Line |
| Voltage | 240VAC, 480VAC, 600VAC, 250VDC |
| Phase | 3 |
| AIC Rating | 42kA @ 240VAC, 25kA @ 480VAC, 22kA @ 600VAC, 10kA @ 250VDC |
| Frame Type | KA |
|---|---|
| Terminal Type | Lugs |
| For Use With | Square D I-Line Panelboards and Switchboards |
| Wire Gauge | 4 AWG - 350 kcmil (Al/Cu) |
| Max Wire | 350 kcmil |
| Min Wire | 4 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed Thermal, Adjustable Magnetic |
| Available Options | Auxiliary Switch, Alarm Switch, Undervoltage Release |
|---|---|
| Accessories | Shunt Trip (120-240VAC), Load Side Lugs |
| Standards | CSA C22.2 No. 5, HACR, IEC 60947-2, NEMA AB 1, UL 489 |
| Approval | CSA, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Visual Trip Indicator |
Product FAQs
7 answersWhat does the -1021 suffix mean on the Square D KA36125-1021?
The -1021 suffix indicates that this circuit breaker includes a factory-installed 120-240VAC shunt trip accessory. This allows the breaker to be tripped remotely via a separate control circuit.
What is the modern replacement for the legacy KA36125-1021?
The KA36125-1021 is a legacy K-Frame breaker. In modern Square D systems, it is typically replaced by the PowerPact H-Frame series, specifically models like the HGA36125SA, which also features an I-Line connection and a factory-installed shunt trip.
Can I install the KA36125-1021 in a standard QO or Homeline load center?
No, this is an I-Line style plug-in molded case circuit breaker. It is designed exclusively for commercial and industrial Square D I-Line panelboards and switchboards, and will not fit in standard residential load centers.
Does the KA36125-1021 require a separate mounting kit for I-Line panels?
No, the KA36125-1021 features an integrated I-Line style plug-in connection. It mounts directly onto the I-Line bus assembly without the need for additional mounting hardware or brackets.
Can I adjust the trip settings on the KA36125-1021?
The thermal overload protection is fixed at 125 amps, but the magnetic short-circuit protection is adjustable. This allows you to fine-tune the instantaneous trip response for your specific application.
Is the KA36125-1021 suitable for 480V commercial systems?
Yes, this breaker is rated for up to 600VAC. When installed in a 480V system, it provides an interrupting capacity of 25kAIC.
Can I use aluminum wire with the KA36125-1021?
Yes, the standard lugs on this breaker are dual-rated for both aluminum and copper conductors, accepting wire sizes from 4 AWG to 350 kcmil.
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Reviews
Review summary
Customers rate this product 4.9 out of 5 based on 14 reviews.
Total 5 star reviews: 13 Total 4 star reviews: 1 Total 3 star reviews: 0 Total 2 star reviews: 0 Total 1 star reviews: 0
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Rating
14 reviews
- RFRon F.Verified BuyerReviewingSquare D KA36150 - 150A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars7/27/26Square D KA36150
As usual, on time and in great condition!
- SJShawn J.Verified BuyerReviewingSquare D KA36225 - 225A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars4/27/26I Line BreKER
Found exactly what I was looking for. They called and set over specs so I could confirm the fit!
- RFRon F.Verified BuyerReviewingSquare D KA36100 - 100A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars4/9/26Multiple orders
I have purchased multiple breakers (of fairly large size) from SuperBreakers and their pricing has been excellent and the delivery time spot on. I would highly recommend them
- MFMatt F.Verified BuyerReviewingSquare D KA36100 - 100A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars8/21/25Order Messed Up - Breaker Great
I have ordered many breakers through SuperBreakers with no issues until this order. I ordered this breaker and it wasn't shipped. I sent a message and was told that a mistake was make in shipping and that they would next day air the breaker to me. 5 days later (weekend in there) the breaker arrived. Not next day air, but shit happens. Sent the breaker still in the box out with my electrician and received a call from him that the breaker that was sent was a KAL36100 not the KA36100. I reached out to SuperBreakers and was told the correct breaker would be next day aired that day and I was emailed a shipping label to send back the incorrect one. This time it arrived the next day and was installed. This error cost my customer a couple days with out power to a dimmer cabinet and about 2 extra hours of labor, but all was okay in the end. Mistakes happen. The help and quick responses to my emails I received from Mike David showed me enough about this company. I look forward to my next order. Thank you for working this situation out in timely manor.
- JHJoel H.Verified BuyerReviewingSquare D KA36200 - 200A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars8/5/25Worked As Planned
They had what we needed to match existing equipment, they shipped the same day and we put it right into service, no problems from first phone call to delivery and install.