Zinsco QB243040 Molded Case Circuit Breaker
- 40A
- 3 Pole
- Bolt-On
Quantity
Zinsco QB243040 - 40A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
Quantity
Zinsco QB243040 - 40A 3 Pole Molded Case Circuit Breaker
New
Quantity
| Brand | Zinsco |
|---|---|
| Part Number | QB243040 |
| Series | QB |
| Amperage | 40A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | QB |
|---|---|
| Terminal Type | Lugs |
| For Use With | Zinsco Panelboards |
| Wire Gauge | 14-6 AWG (Al/Cu) |
| Max Wire | 6 AWG |
| Min Wire | 14 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Accessories | Load Side Lugs Included |
|---|---|
| Standards | UL 489 |
| Approval | UL |
| Temp Rating | 40C |
| Construction Features | Magnetrip, Color Coded Handle (Grey), Common Trip |
Quantity
Zinsco QB243040 - 40A 3 Pole Molded Case Circuit Breaker
Re-Certified
Quantity
| Brand | Zinsco |
|---|---|
| Series | QB |
| Amperage | 40A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | QB |
|---|---|
| Terminal Type | Lugs |
| For Use With | Zinsco Panelboards |
| Wire Gauge | 14-6 AWG (Al/Cu) |
| Max Wire | 6 AWG |
| Min Wire | 14 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Accessories | Load Side Lugs Included |
|---|---|
| Standards | UL 489 |
| Approval | UL |
| Temp Rating | 40C |
| Construction Features | Magnetrip, Color Coded Handle (Grey), Common Trip |
Description
A drop-in replacement for obsolete Zinsco commercial and industrial panelboards, the QB243040 is a 40-amp, three-pole molded case circuit breaker. It delivers reliable thermal-magnetic protection for aging electrical systems. This bolt-on MCCB mounts into existing Zinsco enclosures, eliminating the need for costly panel replacements or adapter kits. It can also be cross-referenced with the UBIZ243040 substitute.Specifications
| Brand | Zinsco |
|---|---|
| Series | QB |
| Amperage | 40A |
| Poles | 3 |
| Mounting Style | Bolt-On |
| Voltage | 240VAC |
| Phase | 3 |
| AIC Rating | 10kA @ 240VAC |
| Frame Type | QB |
|---|---|
| Terminal Type | Lugs |
| For Use With | Zinsco Panelboards |
| Wire Gauge | 14-6 AWG (Al/Cu) |
| Max Wire | 6 AWG |
| Min Wire | 14 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Accessories | Load Side Lugs Included |
|---|---|
| Standards | UL 489 |
| Approval | UL |
| Temp Rating | 40C |
| Construction Features | Magnetrip, Color Coded Handle (Grey), Common Trip |
Product FAQs
5 answersWhat type of panelboards are compatible with the Zinsco QB243040?
This breaker is designed for use in obsolete Zinsco commercial and industrial panelboards that accept bolt-on molded case circuit breakers. It mounts directly into existing enclosures without requiring adapter kits.
Is there a modern substitute available for the Zinsco QB243040?
Yes, the UBIZ243040 is a direct cross-reference and drop-in replacement for this specific 40-amp, 3-pole bolt-on breaker.
Does this breaker require a separate mounting kit for installation?
No, the QB243040 features a bolt-on connection type that mounts directly into compatible Zinsco enclosures, eliminating the need for costly panel replacements or adapter kits.
How does the trip mechanism function on the QB243040?
It utilizes a fixed thermal-magnetic trip unit with long-time and instantaneous (LI) functions. The thermal component responds to sustained overloads, while the magnetic component reacts immediately to short circuits.
Are there any safety concerns with installing Zinsco breakers in older panels?
While this bolt-on breaker provides reliable overcurrent protection, many vintage Zinsco panelboards have known design flaws. Licensed electricians should thoroughly inspect the panel busbars for pitting, corrosion, or signs of arcing before installing a replacement breaker.
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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