This Zinsco electrical panel article discusses the electrical, fire, and shock hazards associated with Zinsco electrical components, circuit breakers, electrical panels, including certain Sylvania electrical panels and breakers which are in fact of the same product design and origin.
We include advice on how to identify Zinsco, Sylvania Zinsco, and Kearney electrical panels and circuit breakers, and repair or replacement advice for those products.
Green links show where you are. © Copyright 2015 InspectApedia.com, All Rights Reserved.
With the exception of the more seriously failing FPE Stab-Lok electrical panels, we have not received any significant number of field failure reports concerning other electrical panel brands that also use aluminum parts and that are or were priced in the same range as Zinsco. This means homes with this equipment may be at greater risk of fire or other electrical hazard.
Limited test results reported by J. Aronstein indicate that the central Zinsco electrical panel and circuit breaker failure problem appears to be burnups at the clip-to-bus connections such as shown in our photo of a burned Zinsco electrical panel bus and breaker. The few circuit breakers tested by Dr. Aronstein were reported to trip within normal overcurrent limits. However a circuit breaker whose bus connection burns can lead to overheating damage to the circuit breaker itself, rendering it non-functional.
Photo (left) of a burned and failed Zinsco main circuit breaker, courtesy of J. P. Simmons - Mr. Electric. Simmons adds: "In this case the failure damaged the main wire to a mobile home also (you can see the melted wire to the left of the main). This is a good example of why I do not like to see anyone remove these breakers. You can not tell how bad they are damaged by looking at them.
Building owners or electricians encountering problems with this equipment are asked to contact us to add that information to our electrical failure data base in an effort to develop accurate safety information which is then shared with appropriate federal and state agencies. Thanks to Mr. James Simmons, a licensed electrician with extensive field experience and the contributor of most of the photos and case reports at this web page.
Where Zinsco electrical panels and Zinsco circuit breakers are in use, arcing, contact-point burn, and even circuit breaker case blow-out have been observed in the field.
Our photo (above left) illustrates a burned-up electrical receptacle whose circuit was protected by a Zinsco circuit breaker that failed to trip and in fact had burned itself in the panel.
A principal Zinsco™ circuit breaker (or Sylvania™ or GTE-Sylvania™ or Kearney™ electrical panel using this circuit breaker) point of failure appears to be at the point of contact where the circuit breaker contacts clip onto the electrical panel bus, combined with the use of an aluminum electrical panel bus.
As described at ZINSCO FAILURE REPORT PROCEDURE, expert testing on this equipment has shown that circuit breakers do not trip about 25% of the time when exposed to overcurrent - risking overheating, fire and other hazards. The failure rate of competitive-brand circuit breakers is much less than 1%.
Readers wanting to read specific advice on what to do if their building contains a Zinsco electrical panel should first read ADVICE FOR ZINSCO OWNERS, then also
In addition to advice on identifying Zinsco™ panels, inspecting Zinsco electrical panels, and repair/replacement
advice, we provide field photographs of
circuit breaker failures: overheating, burnups, failures to trip, overcurrent protection failure.
This document includes field reports of failures and additional
Repair advice (replace the equipment) is provided
Replacement Zinsco circuit breakers and replacement copper-plated bus bars for Zinsco / Zinsco-Sylvania electrical panels are advertised. Without evidence of a design change in the product or support from independent expert testing, the effectiveness of these replacements is not clear.
As a not-for-profit activity, we have been collecting information and field failure reports for Zinsco/Sylvania electrical components since 1996 in an effort to develop credible failure-rate information which is then shared with the U.S. CPSC and with other electrical failure researchers and educators.
Continue reading at GTE-SYLVANIA-ZINSCO FAILURE MECHANISM or select a topic from the More Reading links shown below.
Suggested citation for this web page
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs) about Zinsco & Zinsco-Sylvania electrical panels and circuit breakers
Question: I am selling my house and it has a Zinsco electrical panel - are they all a fire hazard risk?
I am selling my house and just had an inspection done. I have a zinsco circuit breaker panel and would like to know is every model the same and are all of the circuit breaker panels a fire hazard risk? - Suzanne
Thanks for the important Zinsco breaker model question. We don't know if there are Zinsco-brand circuit breakers whose design is different from the ones discussed here (I don't think so), and we don't yet know if there are age or model differences among Zinsco circuit breakers and their performance, because not enough Zinsco breaker testing has yet been completed.
Question: How do I identify a Zinsco electrical Panel or a Sylvania Zinsco Panel & How do I know if My Panel is Bad?
How do I know if my Sylvania electrical breaker is a Zinsco? - Marie
How do I know if my Sylvania electrical panel is bad? - Wallace
Wallace: unfortunately it is not possible nor even safe to try to assure the safety of certain electrical problems by visual inspecting (you can't see hidden problems behind or even inside the circuit breaker) nor by testing in place the circuit breakers (you risk starting a building fire, and even a "tests-ok" breaker may fail the next time it is subjected to an overcurrent). Worse, testing in some cases (FPE in particular) can significantly INCREASE the chances that in the future the breaker will fail to trip.
Marie: see IDENTIFY ZINSCO ELECTRICAL PANELS for help in identifying Zinsco brand electrical panels and circuit breakers.
Question: My Zinsco Main Breaker is in the "Off" Position but power is still on in my panel. Help?
Have a zinsco 100 amp service, turn the main off but still get power have very little cash. So I can't replace it at this time, if I replace the main, is it safe to still use this panel? Is it safe to add new breakers? - Tim
If you still have power when the main electric panel disconnect is in the "OFF" position then this is a VERY dangerous condition as you cannot, using normal homeowner controls, turn off electrical power in an emergency, and more, it is likely that the main disconnect is not going to trip on a large overcurrent and so is not protecting the equipment and building from an electrical fire.
Question: Single Breaker Zinsco-Sylvania 100A Main Service Switch feeds a new GE Panel. Isn't this OK?
I have a Sylvania panel on an exterior wall that simply has 100 amp service to the main breaker and then a single 100 amp breaker on the branch that leads to a new GE panel inside the house with its own 100 amp main breaker.
All power comes off of the GE panel. That being said, this seems safe as to take out the Sylvania I would just have a wire from the meter to the GE panel, which would provide no overcurrent protection anyway. With the Zinsco/Sylvania I have two additional breakers to try to trip if for some reason the 100 amp main in the GE failed, plus I can kill power to the GE panel from the outside if ever I needed to in case of a fire.
Does this sounds fine or is the Sylvania still a problem? - Bob Welderman
Reply: The service entry cable between meter and new panel may be under-protected
First off. Thank you for the response. To be more specific. The wire from the meter to the Sylvania is about 4 feet and then the one from the Sylvania to the GE is about 4-6 feet as it is just on the other side of the wall. The breaker from the Sylvania to the GE is a brand new refurbished one that was tested by the electrical supplier about a year ago. - Bob.
Comment: testing by the electrical supplier? Unusual. But the basic electrical failure risk remains.
Bob, in the arrangement you've described, it is the SEC between the Zinsco-Sylvania breaker and the new GE panel that is left unprotected should a short occur in that wire or should the main breaker in the GE panel fail to trip. I agree that the risk that remains in those components is likely to be lower in frequency than risks of the need to trip a circuit breaker protecting an individual branch circuit in the building. However, because of the chances of a higher current draw at a major failure in a panel or in an SEC, the protection of that wiring is very important. Indeed we attended a house fire that occurred in just those circumstances - an SEC or main panel short.
Just to be clear, the main switch protects equipment that is downstream from itself.
At this point, if I understand your schema, the service entry cable passes from meter to Zinsco-Sylvania breaker and from there to a main panel of another brand. So the risk of a no-trip or burnup in the service panel is less than before when Zinsco breakers were in use in that location.
Nevertheless, it's the main switch that does the heavy lifting when safety and shorts are concerned.
Question: where can I buy replacement electrical panel covers for a Zinsco ?
looking for two electric panel covers for zinsco 14" w x 20 L - Hank Vance
Hank, take a look at the article ZINSCO REPLACEMENT PANELS - This article describes replacement electrical panels and covers.
Question: was there a Sylvania Panel recall?
Sylvania Panel GRTE, 390-205-08, 380-025-15, e-52977, albiz (20-20)-c. Home Inspection comments this could be a recall item. Please advise 650-576-0777 Thank you, B Oliveira - 12/19/11
Brenda, I'm not sure what advice you are asking; please be sure to read the above articles on the hazards of Zinsco and Zinsco-Sylvania electrical panels and circuit breakers. Simply deciding on the presence or absence of a safety hazard based on whether or not there was a product recall is unreliable.
Question: What is Sylvania-Zinsco's responsibility for a faulty product?
What is Sylvania-Zinsco's responsibility for a faulty product? Were there any recall notices? Is there any compensation for their faulty product? - G Butler 5/7/12
The assignment of responsibility for product defects is a legal and technical question that we InspectAPedia do not directly address. We report on building and environmental inspection, diagnosis, and repair topics with as much impartiality as possible. I agree that it's a fair question nevertheless, and as with other controversial product defects such as the FPE Stab-Lok hazard, we will report if there are product recalls or legal actions in the matter.
Question: where do I find a licensed electrician to do Zinsco Panel Replacements?
Where to find licensed electrician for zinsco panel in my area - David Rue 5/16/12
David, ANY licensed electrician can replace a Zinsco electrical panel. The reason we like to use electricians who know about the Zinsco hazard is to avoid wasting time with someone who makes the mistake of telling you there is no possible hazard.
At DIRECTORY OF ELECTRICIANS we list some, not all, electricians who assert that they have experience with Aluminum wiring, FPE, and Zinsco electrical equipment repairs or replacements. There are no listing fees and InspectApedia has no business nor other financial relations with any topic or service provider discussed here.
Question: Zinsco Field Failure Report 7/15/12
I am a Master Electrician in Florida. I recently received a call from a customer who was having a new central A/C installed. The Installer told him that the Main 100A Zinsco breaker was turned off, but the house still had power. I assessed the situation, and told the homeowner he needed a service change. I would not even attempt to touch the service disconnect. I had the Power Company disconnect the power at the transformer, before I started.
When it was safe, I attempted to remove the old Zinsco breaker, and it crumbled in my hands. If someone had attempted to work the breaker they would have been subject to a terrific arc flash - burn - explosion. I,m glad I took the safety first approach. Hank Kline DeBary FL. - Hank Kline 7/15/2012
Thanks so much for your important Zinsco field failure report Hank. It illustrates how one real-world experience is worth a dozen arm-waving speculations from a few writers who think we've made the whole thing up. Glad you knew to be safe.
Question: is there a recall on Zinsco Electrical Panels / Circuit Breakers - or recourse?
Is there a recall or some recourse from the company that manufactured the faulty Zinsco Electric Panel / Circuit Breaker? Do you have a contact for the company? Thanks! - Cynthia 7/23/12
Sorry, Cynthia, no.
Question: is it safe to replace a Zinsco-design electrical panel if I have the electric company drop power at the meter?
I have a Zinsco Panel it is listed as a Sylvania but looks exactly like the photo above. I have a friend that is a electrician and told me he would replace the panel with a new square D 200 amp service. If I have the power company turn my meter off then no power will be running through the panel how is this job still dangerous? - Ryan 8/23/2012
Question: Reader comment: burned-up Zinsco Circuit Breaker Photos
We suggested they immediately get a licensed electrician to come out and replace the panel, but they just wanted to replace the breaker, worryingly enough.
The truly scary part, though, is that apparently this breaker was not the one that originally failed, it was set on fire by the failure of the adjacent breaker. One can only imagine what that one must have looked like, if there was anything left of it.
Feel free to include the photos in the Zinsco section of the website, if you'd like. I think I may end up making a display case in the store for this and a similarly failed FPE breaker. Maybe it'll give people a hint as to why we recommend that they replace these panels.
On a somewhat related note, I regularly recommend your site to customers with electrical safety questions, as does my father (a licensed electrician with over 40 years in the industry). Thanks for all the work you've put into it, and for trying to bring electrical safety issues to people's attention. - A.K.
Thank you for the Zinsco burn-up photos and the case report of another Zinsco circuit breaker failure. Your report is a reminder of Aronstein's frequent caveat that unless the remains of a fire are examined by a very expert forensic expert, we can not always be sure exactly what went wrong.
Nevertheless in the case you describe, and considering that based on an impartial review of the history of Zinsco product failures and field reports, our OPINION is that the product is defective, suffering from both design and performance issues.
What that fancy talk means in plain English is that simply installing a "replacement breaker" into a Zinsco panel is not a safe repair since it does nothing to address the design and product failure issues in the product. As with a few other replacement circuit breaker lines like FPE, there is unfortunately not a shred of independent test data nor field data that would support just replacing the breaker. Replacing the panel is what one should recommend.
The stumbling block for electricians and their customers is that too often all the customer has noticed is that power has been lost on one or two circuits in the building (where a breaker melted or failed to trip until the circuit wiring burned up). The customer figures that "all I need is a new $7.00 circuit breaker" and treats with suspicion the electricians's suggestion that the panel should be replaced.
To offer impartial assistance in problems like this you are welcome to provide your customers with printed copies of InspectApedia articles that you find helpful, and for a few cases listed just below we also provide special web pages that can be freely copied to other websites so long as they are not modified without our permission. Your email prompted us to make a new hazard summary page for Zinsco, Kearney, Zinsco-Sylvania electrical panels & circuit breakers
CONTACT US if you have suggestions for that material or if you have questions or content suggestions about other material at InspectApedia. Working together we're smarter than working alone. Thanks again, Daniel
Question: does voltage drop between zinsco terminal and busbar indicate trouble?
(Mar 8, 2014) Tom Hons said:
Would doing a voltage drop measurement from the screw terminal of a Zinsco circuit breaker to the busbar it is attached to while putting a load on that circuit, tell the condition of the breaker's connection to the busbar? I measured it with no load and it was .005volts and with a load of 3 portable 120volt heaters on, it was 0.131 to .149volt.
That's an interesting question, Tom. I'm not sure of the answer, as there could be multiple explanations for a voltage drop including a defect inside the breaker itself, a poor wire-to-screw connection, etc. Worse I have no confidence that the type of measurement you are making is at all reliable in testing the safety of a circuit breaker.
Breakers are tested by experts by applying a known load or overcurrent to determine the trip point of the breaker under various conditions.
Measurements of resistance (which means taking the panel off line) between various points can be an indicator of trouble: oxidation or other poor connection problems;
The trip curves for circuit breakers are a function of time and current. At higher overcurrents the time to trip gets shorter and shorter until at a dead short the trip time is in milliseconds. DO NOT try these tests on an installed system - the risk is burning down the building or getting shocked.
But absence of a measurement of voltage drop nor increased resistance is definitely no assurance that a breaker will necessarily perform as needed.
Question: The cover of my breaker panel says Zinsco but how would I actually know if its internal guts are ZInsco?
(Aug 5, 2014) Tony B. said:
HI i think i may have a zinsco panel at least the outside metal cover says it is but how would i actually tell if the internals are Zinsco or not can you help me identify this please.
In the More Reading article links above see
IDENTIFY GTE SYLVANIA-ZINSCO PANELS
for photos and text that help you identify Zinsco equipment. You will see that the breaker connectors and bus bars onto whichg they clamp are not like other electrical panel designs.
You are also welcome to use the email found at our CONTACT link to send us photos of your electrical equipment for comment.
Check the FAQs just above, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References
More Reading, found near the top of this page suggest articles closely related to this one.