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Zinsco Q20 Miniature Circuit Breaker
- 20A
- 1 Pole
- Plug-On
Zinsco
Q20
Miniature Circuit Breaker
Brand
Zinsco
SKU
Q20
Quantity
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Zinsco Q20 - 20A 1 Pole Miniature Circuit Breaker
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Description
Engineered for older residential applications, the Zinsco Q20 delivers 20 amps of thermal-magnetic protection. This single-pole component utilizes classic Magnetrip technology to safeguard household wiring. Designed specifically for vintage Zinsco load centers, it mounts securely without aftermarket adapters. This exact fitment is often cross-referenced with the UBIZ20 substitute model. The recognizable red color-coded handle allows for quick visual identification of the 20A rating.Specifications
| Brand | Zinsco |
|---|---|
| Part Number | Q20-R |
| Series | Q |
| Amperage | 20A |
| Poles | 1 |
| Mounting Style | Plug-On |
| Voltage | 120/240VAC |
| Phase | 1 |
| AIC Rating | 10kA @ 120/240VAC |
| Frame Type | Q |
|---|---|
| Terminal Type | Lugs |
| For Use With | Zinsco Load Centers |
| Wire Gauge | 14-8 AWG (Cu/Al) |
| Max Wire | 8 AWG |
| Min Wire | 14 AWG |
| Trip Technology | Thermal Magnetic |
|---|---|
| Trip Function Code | LI |
| Trip Function | Long-Time, Instantaneous |
| Trip Adjustability | Fixed |
| Standards | UL 489, SWD, HACR Rated |
|---|---|
| Approval | UL |
| Temp Rating | 40C |
| Construction Features | Magnetrip, Color-Coded Handle (Red) |
Product FAQs
10 answersWhat load centers are compatible with the Zinsco Q20 circuit breaker?
The Q20 is designed exclusively for vintage Zinsco Q-style load centers. It is not compatible with modern panels from other manufacturers.
Can I use a Zinsco Q20 in a Sylvania electrical panel?
Yes, if the Sylvania panel was manufactured after GTE Sylvania acquired Zinsco and is designed to accept Q-frame or Magnetrip circuit breakers. Always verify the panel label for approved breaker types.
What is the modern replacement for the obsolete Zinsco Q20 circuit breaker?
Connecticut Electric manufactures a direct replacement for the Q20 under the catalog number UBIZ20. This replacement is ETL listed to UL 489 standards for use in Zinsco panels.
Are Zinsco Q20 and QC20 circuit breakers interchangeable?
No. The Q20 is a 1-pole breaker, while the QC20 is a 2-pole configuration. They serve different applications and cannot be swapped.
Are there known safety issues with vintage Zinsco circuit breakers?
Yes. Vintage Zinsco breakers and panels have documented failure modes, including breakers failing to trip during overloads and clips arcing or welding to the bus bar. Many electricians recommend full panel replacement.
Can I install a generator interlock kit on a Zinsco panel using a Q20 breaker?
Installing interlock kits on vintage Zinsco panels is strongly discouraged by safety professionals. The documented risk of breakers failing to trip or welding to the bus bar makes them unsafe for generator backfeeding.
How does the Zinsco Q20 connect to the panel bus bar?
The Q20 uses a plug-on connection with a clip that snaps onto the panel bus bar. Ensure the bus bar is free of pitting, melting, or corrosion before installation, as these are common issues in older Zinsco panels.
What wire materials are approved for the Zinsco Q20 lugs?
The terminal lugs on the Q20 are rated for both copper and aluminum conductors ranging from 14 AWG to 8 AWG. When using aluminum wire, apply a listed oxide inhibitor to prevent corrosion.
What does the LI trip function on the Zinsco Q20 indicate?
The LI designation means the thermal-magnetic trip unit provides Long-Time thermal protection against sustained overloads and Instantaneous magnetic protection against short circuits.
Can a single-pole Zinsco Q20 be used for a 240V appliance?
No. The 1-pole Q20 provides 120V to neutral for standard branch circuits. A 2-pole breaker is required to supply 240V to heavy appliances, even though the breaker carries a 120/240VAC system rating.
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Reviews
Review summary
Customers rate this product 5.0 out of 5 based on 47 reviews.
Reviews Summary
Generated by AI from 91 most recent customer reviews
Last updated 8/1/25
Customers say these circuit breakers arrive quickly and match their specifications perfectly. Many reviews mention success finding hard-to-locate specialty breakers through this supplier. Common feedback includes praise for the accurate product descriptions, reliable shipping, and competitive pricing. While some note occasional stock limitations, users consistently report the breakers fit and function as intended.
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Rating
47 reviews
- CGCrocefissa G.Verified BuyerReviewingSiemens Q115 - 15A 1 Pole Miniature Circuit BreakerI recommend this productRated 5 out of 5 stars9/18/26Quick delivery and great price.
The circuit breakers are at a great cost.
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The product was exactly what I needed and it arrived on time.
- DQDon Q.Verified BuyerReviewingSiemens Q3100 - 100A 3 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars9/14/26Siemens breaker
Great customer experience, great prices and fast shipping... Definitely will be buying her again.
- CSChristopher S.Verified BuyerRated 5 out of 5 stars8/12/26Siemens 60
Perfect new condition
- GSGeorge S.Verified BuyerReviewingSiemens Q2150B - 150A 2 Pole Molded Case Circuit BreakerI recommend this productRated 5 out of 5 stars3/4/26Great service
Every time I call or go online you have the parts I'm looking for.