Square D KC34125G Molded Case Circuit Breaker
- 125A
- 3 Pole
- I-Line
Quantity
Square D KC34125G - 125A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
Description
Belonging to Square D's legacy K-Frame series, the KC34125G is a 125A molded case circuit breaker built for demanding commercial and industrial applications. Featuring an I-Line plug-on mounting style, it installs into Square D I-Line panelboards and switchboards. For modern upgrades, it is replaced by the PowerPact JJA36125. Rated for 65 kAIC at 480VAC, it utilizes thermal-magnetic trip technology (LI) and includes a ground fault shunt trip accessory.Specifications
| Brand | Square D |
|---|---|
| Part Number | KC34125G-R |
| Series | KC |
| Amperage | 125A |
| Poles | 3 |
| Mounting Style | I-Line |
| Voltage | 240VAC, 480VAC, 250VDC |
| Phase | 3 |
| AIC Rating | 100kA @ 240VAC, 65kA @ 480VAC, 10kA @ 250VDC |
| Frame Type | KC |
|---|---|
| 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 | Shunt Trip, Auxiliary Switch, Alarm Switch, Undervoltage Release |
|---|---|
| Accessories | Ground Fault Shunt Trip, Load Side Lugs |
| Standards | CSA C22.2 No. 5, IEC 60947-2, NEMA AB 1, UL 489 |
| Approval | CE, CSA, HACR, NOM, UL |
| Temp Rating | 40C |
| Construction Features | HACR Rated, Extra High Interrupting Capacity, Non-Interchangeable Trip |
Product FAQs
8 answersWhat panelboards accept the KC34125G circuit breaker?
This breaker mounts directly into Square D I-Line panelboards and switchboards. The plug-on design engages the busbar stack directly without requiring separate mounting hardware or cable connections to the line side bus.
Are the lugs on the KC34125G suitable for both aluminum and copper wiring?
Yes, the factory-installed mechanical lugs are dual-rated for aluminum and copper conductors. They accept wire sizes from 4 AWG up to 350 kcmil. Always apply an approved oxide inhibitor when terminating aluminum conductors to prevent galvanic corrosion.
How does the adjustable magnetic trip function work on this K-frame breaker?
While the thermal (long-time) trip is fixed at 125A, the magnetic (instantaneous) trip threshold can be adjusted. This allows panel builders to fine-tune the short-circuit response to coordinate with downstream devices and specific motor or equipment inrush currents.
Is the KC34125G an active product line or a legacy frame?
The KC frame is a legacy molded case circuit breaker. For new installations, Square D typically recommends the PowerPact H or J frame breakers, though the KC series remains widely used for replacing existing I-Line breakers in older switchboards.
What does the "G" suffix indicate in the KC34125G catalog number?
The "G" suffix indicates this thermal-magnetic circuit breaker is factory-equipped with a ground fault shunt trip accessory. This allows the breaker to be used in conjunction with a Square D Ground Fault Module (GFM) to provide equipment ground fault protection.
What does the "C" in the KC frame designation represent?
In Square D legacy nomenclature, the second letter indicates the interrupting capacity tier. The "C" designates an extra-high interrupting rating, which provides a higher fault current clearance capability compared to standard "A" or high "H" tier K-frame breakers.
Can this breaker be used in DC applications?
Yes, the KC34125G is rated for use in DC circuits up to 250VDC with an interrupting capacity of 10kA. When applying this breaker in DC systems, ensure proper wiring configurations are followed per manufacturer guidelines for multi-pole DC switching.
How is the KC34125G secured within an I-Line panelboard?
The line side features plug-on jaws that engage directly with the vertical bus stack. The load side is secured to the panelboard backpan using a captive retaining screw, ensuring a rigid mechanical connection that withstands short-circuit magnetic forces.
SuperClub
Join free. Get 500 SuperPoints.
Earn points on eligible purchases and redeem them at checkout.
100 SuperPoints = $1 off.
Warranties
Add an extra year of protection
60-Day Warranty
Your purchase includes 60 days of SuperBreakers warranty coverage.
Add a 1-year warranty extension in your cart.
Get a Quote
Don’t see what you’re looking for?
We source obsolete and hard-to-find parts every day.
Shipping
Free Shipping Policy
Parcel shipments with item value over $99 qualify for free economy shipping within the continental US. Please call to confirm special handling instructions. We do not charge a handling fee or require a minimum amount on any order. SuperBreakers does not ship on customer accounts.
Same Day Shipping
We strive to ship out your items the same day the order is placed. In rare circumstances SuperBreakers may reserve up to 5 business days to consolidate orders for complete shipment.
Expedited Shipments
Orders being shipped via Next Day Air, 2 Day Shipping or 3 Day Shipping must be received by 3 PM EST to guarantee same-day shipments. Expedited orders only ship on normal business days. Shipments will NOT be sent out on Saturdays and Sundays.
International Shipping
All International orders require a $1,000 minimum order threshold. Due to the special nature of these shipments, we require that these be placed with a SuperBreakers representative. Additional shipping and instructions will apply. All International Orders are Non-Cancel and Non-Refundable.
Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 1 review.
- TDTammy D.Verified BuyerReviewingSquare D KC34200 - 200A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars7/9/26Breakers
great service!! I had bought 3 different breakers & there was one that i had to return. I called as soon as i realized it was wrong.( my fault) I had my return RMA in about 5 minutes of the phone call. Highly recommend!!