Zinsco QB243050 Molded Case Circuit Breaker
- 50A
- 3 Pole
- Bolt-On
Quantity
Zinsco QB243050 - 50A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
Description
Restoring older commercial systems requires precise components, and this 50A three-pole breaker delivers exact compatibility. Designed for legacy Zinsco panelboards, it provides reliable thermal-magnetic protection for 240VAC applications. Finding the right fit for obsolete enclosures is easy, as this bolt-on unit mounts into original hardware seamlessly. Featuring the classic Magnatrip mechanism and a black color-coded handle, it maintains historical panel aesthetics with a 10kA rating.Specifications
| Brand | Zinsco |
|---|---|
| Part Number | QB243050 |
| Series | QB |
| Amperage | 50A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Terminal Type | Lugs |
|---|---|
| For Use With | Zinsco Panelboards |
| Wire Gauge | 14-4 AWG (Al/Cu) |
| Max Wire | 4 AWG |
| Min Wire | 14 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 | Common Trip |
Product FAQs
6 answersWhich panelboards accept the Zinsco QB243050 circuit breaker?
This 3-pole breaker is designed specifically for legacy Zinsco bolt-on panelboards. It will not fit in standard plug-on load centers or panels manufactured by other brands.
Are there safety concerns when installing replacement breakers in Zinsco panels?
Yes. Legacy Zinsco panelboards have well-documented safety issues, including breakers failing to trip during overcurrent events and poor connections to the aluminum busbars that can lead to arcing. Many licensed electricians recommend a complete panel upgrade rather than replacing individual breakers.
Does the QB243050 go by any other catalog numbers?
Yes, this breaker is frequently identified by the alternate part number QB2430-50. Both numbers represent the exact same 50A, 3-pole bolt-on breaker for Zinsco panels.
How is the QB243050 secured to the panelboard?
It utilizes a bolt-on connection, meaning it must be mechanically fastened to the panel busbars using screws. This provides a secure connection, but requires the panel to be completely de-energized before installation or removal.
What is the proper wire size for the QB243050 terminals?
The load lugs on this breaker accommodate 14 AWG to 4 AWG wire. They are rated for use with both aluminum (Al) and copper (Cu) conductors. Ensure proper torque is applied during installation to prevent loose connections and overheating.
What type of protection does the QB243050 provide?
It features a fixed thermal magnetic trip unit with Long-Time and Instantaneous (LI) functions. The thermal component protects against sustained overloads, while the magnetic component provides immediate tripping during short-circuit faults.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 1 review.
- MCMarcos C.Verified BuyerReviewingEaton / Cutler-Hammer QB1030GF - 30A GFCI Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars11/20/25circuit breakers
good product and showed up on time