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ZINSCO SYLVANIA ELECTRICAL PANELS
Zinsco panel or circuit breaker field failure report page: here we provide field failure reports and additional photographs of burned or failed Zinsco and GTE-Sylvania-Zinsco electrical panels and circuit breakers. This website 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.
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Zinsco Panel or Breaker Failure Reports: Collection of Field Failure Reports for Zinsco Circuit Breaker/Panel & Sylvania Electrical Panels
Zinsco Panel / Breaker Failure Rate Data
We [J Simmons] see damage in about 25% of the Zinsco/Sylvania panels that are checked. The problem occurs mostly on circuit breakers feeding circuits that have a steady heavy load on them (like heaters, hot water tank, dryer), and on circuits that are often overloaded such as circuits that supply the kitchen or bathroom.
In houses with Zinsco/Sylvania electrical panels and circuit breakers, I [Simmons] have tested these circuits with up to 30 amps on a 20 amp circuit breaker. The Zinsco circuit breaker will carry the overload for a long time without tripping.
This causes the connection to heat up and start arcing to the buss bar. The problem is primarily in the panels with aluminum buss bars, but also has been seen in the ones with copper buss. Moisture seems to accelerate the process. Readers should also see ZINSCO FAILURE REPORT PROCEDURE to homeowners when a Zinsco Sylvania electrical panel is observed by a contractor, home inspector, or electrician.
The following anecdotal reports of Kearney, Zinsco, & Zinsco-Sylvania circuit breakers & electrical panels describe observations of failures in Zinsco and Zinsco-Sylvania electrical panels, buses, circuit breakers.
Since most home owners and electricians are more focused on immediate electrical repair and safety needs than in taking photographs and writing failure reports, our opinion is that number and frequency of these electrical failure field reports are the "tip of the iceberg" of actual occurrence. (At left, the photo of a burned Zinsco main circuit breaker and burned greased Zinsco electrical panel bus was provided by Washington state electrician J. P. Simmons)
We estimate that only 2% to 5% of electrical failures are recognized and reported to the U.S. CPSC or to researchers such as Daniel Friedman or Jess Aronstein. This opinion is supported by a US CPSC study of failed electrical receptacles.(1).
The citations below are representative of comments observed at Mike Holt's Page on Zinsco Breakers - http://www.mikeholt.com/forum/Forum1/HTML/005092.html as of 3/8/2006. Holt's page contains additional information. Emails were deleted from the text here for privacy.
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Frequently Asked Questions (FAQs) about field reports & photos of Kearney, Zinsco, & Zinsco-Sylvania circuit breaker, panel & bus failures
Question: why do some sources recommend replacing Sylvania/Zinsco panels when the failure rate is less than 100%
I've been reading the information on your site and from what I gather, you cannot tell which panels are "bad" and need to be replaced? Rather, you suggest that ALL Sylvania/Zinsco panels should be replaced? Am I reading the correctly? - C. anon 12/23/2013
Let me say first that we have less data on Sylvania-Zinsco than on some cousin bad-performing electrical equipment such as the FPE Stab-Lok design. But the underlying safety concern is the same: if we have a circuit breaker that does not trip in response to overcurrent when it should the risk of fire, loss, or injury is significant.
If we have a population of hundreds of millions of circuit breakers of various brands among whom the industry no-trip rate is say .0000001, that's a pretty good safety performance level. But if among that population there are some specific brands and designs that have a no trip record of say 65 in 100, that's by comparison a terrible performance.
It is true that among that latter group of 100 cases we don't in advance know which 65 breakers are not going to trip, then by calling for a replacement of all of them (or their panels where the safety and design issues include panel and bus design and components) we're going to replace 35 breakers that would have worked OK.
So how do we reach such an opinion?
It's not by comparing the 35 good guys to the 65 bad guys of brand X. It's by comparing the 100 brand X "guys" with a failure rate enormously worse than any 100 guys chosen among the larger population of brand A,B,C. (To be more accurate, even among A,B,C the failure rates are not all identical, but in general they are significantly different than X).
What we have are field failure reports that identify certain products as performing significantly worse than others assigned to do the same job. Experts like Aronstein have explained that only a very small percentage of electrical field failures are ever reported to anybody and that even among those often the on-site forensic work is inexpert and does not properly trace a fire to its electrical origin (or the electrical origin has been lost in a burn-up). Therefore industry experts take field failures seriously and opine that they almost certainly represent a larger failure number than is actually reported.
There is no doubt that the Zinsco and Sylvania-Zinsco products enjoy a burn problem at the breaker to bus connection and that breakers are reported to not only fail to trip but to actually explode or burn out at the breaker side - a problem that does not appear enough to create such reports among other brands.
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