Zinsco QFB24-125-3 Molded Case Circuit Breaker
- 125A
- 3 Pole
- Bolt-On
Quantity
Zinsco QFB24-125-3 - 125A 3 Pole Molded Case Circuit Breaker
New
Quantity
Description
Built for three-phase commercial environments, this 125-amp molded case breaker delivers robust thermal-magnetic protection for legacy electrical systems. The bolt-on design mounts securely into compatible Zinsco panelboards, ensuring a precise fit for aging infrastructure. Featuring a 10kA interrupting rating at 240VAC, it utilizes classic Magnatrip functionality to handle overloads and short circuits effectively in demanding industrial setups.Specifications
| Brand | Zinsco |
|---|---|
| Part Number | QFB24-125-3 |
| Series | QFB |
| Amperage | 125A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Terminal Type | Lugs |
|---|---|
| For Use With | Zinsco Panelboards |
| Wire Gauge | #4 AWG - 300 kcmil |
| Max Wire | 300 kcmil |
| Min Wire | #4 AWG |
| 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 | 40C |
| Construction Features | Magnatrip |
Product FAQs
6 answersCan I use this QFB series breaker in a modern load center?
No. The QFB24-125-3 is specifically designed for legacy Zinsco panelboards. It will not fit or function safely in modern panels from other manufacturers like Square D, Siemens, or Eaton.
How is the QFB24-125-3 secured inside the panelboard?
This is a bolt-on breaker, meaning it fastens directly to the panel busbar with screws or bolts rather than snapping into place. This provides a highly secure, vibration-resistant connection suitable for commercial applications.
What wire sizes are compatible with the load lugs on the QFB24-125-3?
The included load side lugs accept wire gauges from #4 AWG to 300 kcmil. When installing, verify that your conductor material and size are rated for the 125A load and properly torqued to ensure a secure connection.
What does the Magnatrip feature refer to on this Zinsco breaker?
Magnatrip is Zinsco's legacy trade name for their thermal magnetic trip mechanism. It provides standard Long-Time and Instantaneous (LI) protection to safely clear overloads and short circuits.
What should be inspected before installing a replacement Zinsco breaker?
Legacy Zinsco panels are known for historical issues, such as busbar burning and poor breaker contact. A licensed electrician must inspect the panel busbars for any signs of pitting, corrosion, or heat damage before bolting on a replacement breaker.
Is the original Zinsco QFB24-125-3 still manufactured?
The original Zinsco brand is obsolete and no longer in production. When sourcing this breaker, you will typically find original legacy stock or aftermarket replacements specifically engineered to fit vintage Zinsco panelboards.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 2 reviews.
- RFRuss F.Verified BuyerReviewingMilbank UQFB-150 2 Pole Circuit BreakerI recommend this productRated 5 out of 5 stars6/26/26Breaker Purchase
This product arrived very quickly...in one day!
It was advertised and was installed successfully
- DDdaniel d.Verified BuyerReviewingMilbank UQFB-150 2 Pole Circuit BreakerI recommend this productRated 5 out of 5 stars3/4/26good
fits perfectly in the 320 we have. no problems