This Zinsco electrical panel article gives the complete chronological history of the Zinsco brand of electrical panels and circuit breakers, including Zinsco, Sylvania Zinsco, and Kearney electrical panels and circuit breakers.

In this article series we discuss: the hazards of Zinsco or Zinsco-Sylvania electric panels; Zinsco & Zinsco/Sylvania electrical panel identification guides & Kearney electrical panel identification guide. Independent testing of Zinsco breakers confirms failures.

Zinsco History, Age, Dates & Patents for Zinsco Electrical Panels & GTE-Sylvania Zinsco Electrical Panels

Zinsco electrical equipment was sold in the U.S. from 1935 to 1984. and its antecedents date from 1891 with the design of Frank Adams electrical panels.

Watch out: Zinsco electric panels, including their currently-sold versions and replacement breakers do not meet the safety and performance of most electrical panels sold under most other brands.

Photo: label in a Frdank Adam electrical panel.

[Click to enlarge any image]

See ZINSCO SAFETY PRECAUTIONS GTE Sylvania Zinsco Electrical Panel Safety Precautions for Homeowners and Home Buyers and also,

ZINSCO/SYLVANIA ELECTRICAL PANELS discusses these latent safety hazards in homes.

Chronological History of Zinsco Electrical Panels

• 1891 Frank Adam Electrical Panels

  Frank Adams Electrical panels were installed in buildings in the U.S. roughly between 1900 and 1950, possibly as late as 1970. Contact us if you have photos of a Frank Adams electrical panel or other details.

  Frank Adam Electric, founded in 1891 in St. Louis MO, descended from a watch and surveying equipment manufacturer, Blacker and Adam Watch Co.

  Emile Zinsmeyer, founder of what later became Zinsco Electric, was employed at Frank Adam's retail sales, moving to California in the 1920's to operate Frank Adams business there.

  Zinsmeyer purchased Adams' stock in California in 1929, founding Zinsmeyer Co. with family members and continuing to operate in California. - Source: Historical report indicates that Frank Adam Electric, formed in 1891, operated on the U.S. west coast. - Heather Hill to Mike Holt, note posted at Mike's forum, no longer on-line (2018).
  
  Frank Adam Electric Co. continued to operate, as indicated in some of the patent citations we include below showing inventions assigned to Frank Adam Electric Co. ranging from 1906 to at least 1965.
  
  See details at IDENITFY FRANK ADAM ELECTRICAL PANELS
  

• 1903: Adams, Frank. "Electric canal system." U.S. Patent 728,823, issued May 26, 1903.
• 1905: Adams, Frank. "Electric railway." U.S. Patent 807,984, issued December 19
• 1906, Adam, Frederick B., Service Entrance Box, U.S. Patent 851726, issued April 30, 1906, assigned to Frank Adam Electric Co.

• 1929 (est) Zinsmeyer Electric formed by Emile Zinsmeyer, from Frank Adams' CA stock. Emile Martin Zinsmeyer. According to a Wikipedia writer, the forerunner of Zinsco was a west coast division of Frank Adam Electric Company, re-named Zinsmeyer Company after 1929.
  
  The rest of this Zinsco history and list of dates was collected by the author [DF] from patents and news articles.
• 1934: Green, Floyd S. "Circuit interrupting and protecting apparatus." U.S. Patent 1,966,716, issued July 17, 1934. Assigned to Frank Adam Electric Co.
  
  Green, Floyd S. "Dead front safety switch." U.S. Patent 1,962,867, issued June 12, 1934.
• 1943 Zinsco Electric formed: Martin Zinsmeyer purchased the Zinsmeyer company from his father, renaming it Zinsco Electrical Company as appears in the following patents.
• 31 May 1946 - priority date: Patent :Zina, Roy Stanley. "Electrical panel board switch." U.S. Patent 2,530,548, issued November 21, 1950. Original assignee: Zinsco Electrical Products. Additional patent citations and assigns continue through the 1960's to 1968.
• 1949: Patent: William, Myers John. "Electrical bus structure." U.S. Patent 2,477,523, issued July 26, 1949. Assigned to Zinsmeyer Company.
  Excerpt:
  This invention relates to panel boards, switch boards, and similar electrical service installations such as employed in factories, theatres, and other installations for the distribution of electricity to the various circuits.
  
  More specifically, the present invention relates to the bus structure employed in such switchboards and panel boards for the distribution of electrical current from the current supply cables to the various switches and circuit breakers which control the circuits or to any other electrical instruments or devices which are commonly mounted in switchboards and panel boards.
• 1950: Speck, Ernst. "Circuit breaker." U.S. Patent 2,502,537, issued April 4, 1950.
• 1959: Green, Floyd S. "Panel board." U.S. Patent 2,576,396, issued November 27, 1951. Assigned to Frank Adam Electric Co.
  Means of mounting various devices in an electrical panel board.
• 1959: Locher, Ross E. "Multiple circuit breaker." U.S. Patent 2,878,332, issued March 17, 1959. and also "Interlock mount for switch." U.S. Patent 2,869,043, issued January 13, 1959. Assigned to Zinsco Electrical Products
• 1961 Ellegood, Pruett W. "Distribution switchboard." U.S. Patent 2,997,627, issued August 22, 1961. - assigned to Frank Adam Electric Co.
• 1964: "Terminal for circuit breaker switch or the like." U.S. Patent 3,138,421, issued June 23, 1964. Assigned to Zinsco Electrical Products
• 1965: Hercules, L.A., FRANK ADAM ELECTRIC CO, 1965. Enclosed switch with defeatable door interlock. U.S. Patent 3,188,410. Assigned to Frank Adam Electric Co.
  
  See FRANK ADAM ELECTRICAL PANELS for example photos of Frank Adam panels, a split bus panel design, and Frank Adam panel identification labels.
• 1966 "Meter pedestal." U.S. Patent 3,286,133, issued November 15, 1966. assigned to Zinsco Electrical Products and
• "Electrical distribution box and neutral." U.S. Patent 3,265,937, issued August 9, 1966. - Sturdivan's patent sketch is shown at left. Assigned to Zinsco Electrical Products
• 9 June 1972: Patent: Mendel, J., and R. Whitaker. "Ground fault protection system." U.S. Patent 3,727,106, issued April 10, 1973. Assigned to Zinsco Electrical Products
• 1972: "Ground fault detector circuit." U.S. Patent 3,700,967, issued October 24, 1972. Assigned to Zinsco Electrical Products
• 1973: Zinsco Electric sold to GTE-Sylvania Electric who continued to manufacture the original breaker-design. GTE-Sylvania marketed electrical panels of the original Zinsco design under the Zinsco brand as well as under the GTE-Sylvania Zinsco brand.
• 1976: Gehrs, Donald F., and David T. Higgins. "Electrical bussing and jumper assembly." U.S. Patent 3,995,103, issued November 30, 1976. Assigned to Zinsco Electrical Products
• Challenger Electrical Equipment Corporation purchased the GTE-Sylvania Zinsco brand

Photo above: a Zinsco electric meter base.

• 1984 Zinsco GTE-Sylvania product line sold to Verizon possibly via Challenger Electric
• Undated: sales of Challenger Electric to Westinghouse - Westinghouse Electric Corporation purchased the Zinsco design & brands from Challenger [or Verizon?]
• Undated: sale of the Zinsco product line by Westinghouse to Cutler Hammer - Cutler Hammer Corporation purchased the Zinsco design & brands from Westinghouse Electric. See CUTLER HAMMER ELECTRICAL PANELS
• Eaton purchased / merged with Cutler Hammer form that present corporation.

• 2011 - 2012: Owner of counterfeit FPE & Zinsco circuit breaker company fined & sentenced to jail
  
  BUSINESS OWNER PLEADS GUILTY TO TRAFFICKING IN COUNTERFEIT CIRCUIT BREAKERS [PDF] - source: U.S. Immigration and Customs Enforcement, retrieved 2018/05/02, original source
  
  Elod Tamas Toldy, owner of Pioneer Breaker and Control Supply sentenced to federal prison for mail fraud and trafficking in counterfeit goods and services for marketing
  
  COUNTERFEIT CIRCUIT BREAKERS on eBay [PDF], under the brand names Zinsco and FPE Stab-Lok. Source: U.S. Immigration and Customs Enforcement, retrieved 2018/05/02, original source https://www.ice.gov/news/releases/texas-business-owner-sentenced-counterfeit-circuit-breaker-scheme - ICE Office of Public Affairs at (202) 732-4242.
  
  Members of the public can report suspected counterfeit operations by calling the U.S. Homeland Security Investigations HSI’s toll-free hotline at: 866-347-2423.
• 2012 Zinsco Red-Tagged in Napa: 20 June 2012, City of Napa, California requires replacement of Zinsco Main Service Panels
  
  REQUIRED SERVICE CHANGES for NEW SOLAR or ANY OTHER NEW APPLIANCE INSTALLATIONS - ZINSCO RED-TAG [PDF] Source: City of Napa, 1600 First St., PO B 660, Napa CA 94559, 20 June 2012
  
  To: Solar Photovoltaic Installers and Mechanical Contractors
  From: Dan Kavarian, Interim Building Official
  Date: June 20, 2012
  
  RE: Required Service Changes for New Solar or Any Other New Appliance Installations
  
  Effective immediately the City of Napa Building Division will require a service upgrade for any Solar Photovoltaic or Any New Appliance installation (i.e. furnace/ac) where the main service is a Zinsco Manufactured meter main.
  
  Due to complications from these service panels in the past and the difficulties acquiring new breakers for future circuits, we have come to the conclusion that we will no longer support the use of these panels in this type of application.
  
  At time of plan submittal the manufacturer of the service main must be shown on the plans and approved prior to permit issuance. If there is an existing Zinsco meter main, you will then be asked to contact PG&E to obtain a service planning request.
  
  All service upgrades must have PG&E approval and be tagged by us prior to reconnect. Your permit will not receive a final inspection if this is an outstanding issue.
  
  Any service upgrades done without PG&E approval will be "RED TAGGED" and the project will be put on hold. If the inspector performs and inspection on your project and a Zinsco meter main is in place and is not identified on the plans, the job will also be stopped and a "RED TAG" will be issued and you will be held responsible for all penalties charged.
  
  
• 2018: Jesse Aronstein ¹, (Life Senior Member, IEEE), & David W. Carrier ² MOLDED CASE CIRCUIT BREAKERS - SOME HOLES IN THE ELECTRICAL SAFETY NET [PDF] Received December 4, 2017, accepted January 24, 2018, date of publication February 7, 2018, date of current version March 15, 2018.
  
  Digital Object Identifier 10.1109/ACCESS.2018.2803298 1 Consulting Engineer, Schenectady, NY 12309, USA, 2 SUNY Dutchess Community College, Poughkeepsie, NY 12601, USA, Corresponding author: Jesse Aronstein (AronsteinJ@verizon.net)

Watch out: OPINION: we do not recommend installing "replacement" Zinsco circuit breakers as there some indications that the performance and safety of those devices may be poor.

Mike Holt has provided excerpts of a history of Zinsco Electric quoting the company founder's great-grandaughter Heather Hill (un-dated). - http://codeforum.mikeholt.com/

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-07-19 by Alice Arriola

Is anyone able to tell me the year and model number of this panel?

This Q&A were posted originally at

IDENTIFY GTE SYLVANIA-ZINSCO PANELS 

On 2023-07-19 by InspectApedia Publisher (mod) - what is the age of this Zinsco Panel?

@Alice Arriola,

Thanks for the question that I'll re-state for other readers as "How Old is This Zinsco Electrical Panel?"

That's an older Zinsco electrical panel label, NOT a later GE-Sylvania-Zinsco panel (the subject of this page where you are posting).

Probably original to the building where it is installed.

See more help on getting an accurate idea of the age of your Zinsco panel at

ZINSCO ELECTRICAL PANEL HISTORY & AGE

https://inspectapedia.com/electric/Zinsco-Electrical-Panel-Age.php

and at

ELECTRICAL PANEL AGE inspectapedia.com/electric/Electrical-Panel-Age.php

PLEASE TELL US: the country and city and age of the building where this electrical panel is installed.

And post photos of any other labels on the panel and a photo giving full view of its breakers.

Watch out: I notice that Los Angeles appears on your Zinsco label. As we note above on this page,since 2012, the City of Napa, California requires replacement of Zinsco Main Service Panels

Watch out: I also see a bit of rust in that panel - it may be rust/water damaged so adds that hazard to the general Zinsco circuit breaker hazard discussed in this article series.

 

On 2020-07-24 by Clint

Can anyone identify this type of electrical panel? Thanks.

Can anyone identify this type of electrical panel?

On 2020-07-24 by (mod) - replace unreliable Outdoor Zinsco electrical panel

Clint

The red and green breakers are characteristic of a Zinsco brand electrical panel.

Watch out: you can confirm the panel ID and read about specific Zinsco safetyconcerns

at ZINSCO SYLVANIA ELECTRICAL PANELS

Near the end of that page at the more-reading article list you'll see articles on how to identify several versions of Zinsco, Zinsco-Sylvania, & Zinsco-Kearney panels.

...

Continue reading  at ELECTRICAL PANEL AGE from CONTEXT CLUES - answer these questions to permit a reasonable guess at electrical panel age, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ELECTRICAL PANEL AGE
• ZINSCO SYLVANIA ELECTRICAL PANELS - home
  • IDENTIFY ZINSCO ELECTRICAL PANELS
  • ZINSCO CIRCUIT BREAKER TEST REPORT
  • ZINSCO SUMMARY PAGE for Reproduction

Suggested citation for this web page

ZINSCO ELECTRICAL PANEL HISTORY & AGE at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to ELECTRICAL INSPECTION & TESTING

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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