The Zinsco Electrical Panel, Zinsco Circuit Breakers - Is This Product OK to Use?

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Zinsco panel and breaker safety opinions:

Here we report email correspondence from a reader whose view is that the Zinsco material has been too one-sided in its criticism of that product.

We include comments by industry experts who respond with explanation of the actual hazards and real failure occurrences of this product.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Zinsco Electrical Panels are "Not so Bad" according to one correspondent

Zinsco breaker burnup (C) J P Simmons & D J FriedmanThis 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.

Our experience and advice indicate that Zinsco and Zinsco-Sylvania circuit breakers of the design described here do not offer the level of overcurrent and fire protection provided by most other electrical panels and circuit breakers.

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.

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 0.01%. That is, these product failures appear to occur at more than 2500 times more often than those of similar competitive equipment.

With the exception of the more seriously failing FPE Stab-Lok electrical panels, we have not received a large 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 are at greater risk of fire or other electrical hazard. [Other than FPE (first offender) and Zinsco, we have received a small number of Challenger and Bulldog Pushmatic complaints, along with other more rare reports under other brands.]

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.

Watch out: while opinions about aluminum components in electrical panels flash below, more significant are the actual Zinsco failure mechanism discussed at GTE-SYLVANIA-ZINSCO FAILURE MECHANISM and the actual reports & descriptions of field failures seen at ZINSCO FAILURE REPORTS.

The principal failure in Zinsco & GTE-Sylvania Zinsco electrical panels appears to be overheating and corrosion developing at the circuit-breaker-to-bus connection, resulting in overheating, failure to trip, and even circuit breaker explosions.

Older background Zinsco correspondence from an electrical panel retailer / reader who has a different point of view

Newest correspondence is at the top of this text, with minor edits to text for public presentation or clarity. Reader Doug H's remarks are in italics.

Email Discussion Re: Zinsco and Zinsco-Sylvania circuit breakers

D Friedman to Doug H:



Regarding your statement, below,

Bottom line is aluminum seems to be a light duty product for light duty service, and preforms well so long as one doesn't use it for anything different, however people seem to do that so i'm not one to always blame the product for what the people do.

Watch out: the above remark is dangerously confusing and inaccurate:

Aluminum electrical wiring is a case in point for generic problems with aluminum at electrical connections. See ALUMINUM WIRING HAZARDS.

Aluminum electrical components in panels, buses, connectors, often perform usually acceptably - but in the case of Zinsco, where failiures have been independently tested and found ocurring roughly 2500 times more frequent than with competitive products, we just can't say it's all the same or that the Zinsco problem is due to mis-use of the equipment.

The problem is not one of mis-use or "performs so well so long as ..." as you indicate - that argument is defeated by the observation that aluminum material in electrical panels performs so inconsistently comparing Zinsco, for example, with GE panels using similar aluminum components.

To say that the Zinsco failures are occurring because people use those panels improperly is to infer that people who buy a Zinsco product use differently than people who buy a GE, Siemens, ITE, or other products of similar rating and use.




Doug H. to D Friedman

Doug comments: Bottom line is aluminum seems to be a light duty product for light duty service, and preforms well so long as one doesn't use it for anything different, however people seem to do that so i'm not one to always blame the product for what the people do.


From D Friedman to Doug H:

I wanted to add, FYI, two other thoughts for us to discuss

DF: 1. Lots of electrical panels have aluminum components - but only Zinsco shows the failures that you see in the articles that I've posted

Doug comments: [Point well taken, but i beg to differ. Many electrical panels with Aluminum are having troubles. Aluminum may be cheaper and run cooler, but it seems to have issues under heavier loads now doesn't it?]

Daniel replies to Doug's comment: because equipment failures occur under normal loads and because the failure mechanism of aluminum wiring is traced to microfretting that occurs under normal loads, that's not an accurate conclusion.

Further, as I point out in a later message above in this thread, if failures occur on product brand A and not on similar product brand B, to claim that A's problems are due to load or usage is to claim that for some reason consumes use brand A differently than they use brand B - a claim that has no supporting evidence.

DF: 2. It is not at all the case that the only choice between a Zinsco panel and others is to go to a costly copper bus 200A panel - at Home Depot I have bought a 100A GE panel, complete with circuit breakers already in the box, for less than $100.

Doug comments: Yes, but is a crappy made in China box really better than a crappy Zinsco box. LOL. But in seriousness the Zinsco 200 amp, aluminum bussbar panel, would need to be replaced with an equivilent 200 amp copper busbar panel, and it's not as much the cost of the $250 panel as it is the cost of the labor. Just a lot to ask of a homeowner that has a Zinsco 200 amp aluminum bussbar panel, in an all gas home, that doesn't come even near to over-loading the light duty panel.

Daniel replies to Doug: nothing in our content specifies a requirement to change panel material, cost, price point - *any* electrical product must perform as rated and certified. If a product does not, it is not giving the level of protection afforded by industry standards, nor by its competitors.


Daniel F. to Doug H:

I appreciate the professional level of discussion,
I am continuing to review and work on this, and when I update the text I'll ask you to take a look at it.

Doug Comments: You are a polite person with good manners. Somebody raised you right. But not necessary for me to critique your websight. It is your business and i really shouldn't be messing in it. Just my dad was a school councelor, so he taught us kids how education is 'suppossed' to work. Meaning gathering as much info as possible, and giving both sides the story, without leading the wittness.

Only through this can people make good decisions based on their own individual circumsatnaces. There doesn't seem to be a one fix for everything in this world.

DF continues: I'm unclear about whether the problem of bus burnups and breaker burnups is due to the level of amps draw - with these arguments in mind:

1. the problem may instead be due to scoring the bus when the breaker is inserted, or due to an innate connection design problem between the breaker and bus, or due to a no-trip problem inside the breaker; Aronstein's work on microarcing that underlies the aluminum wiring overheat problem might be going on with this product as well. [Yes i agree. Many causes possible, but most usually, if not most always, burnouts are caused by heat resulting from a poor connection. Even a light load on a bad connection seems to eventually fail]

2. regardless of the price point, no circuit breaker should burn up the bus or burn up itself in usage - at overcurrent, the breaker has to trip, period, so if a circuit is overloaded the breaker has to open the circuit; regardless of its cost.

[Yes, i knew all along this is the basis of your article, and it is a valid and just point, however the argument to this is often times the device is being used for something it's not intended to do, which may cause the breaker to be damaged, thus it can't trip as it should, thus forcing a burnout.

A good example is the 20% rule. One shouldn't continuously load a circuit with more than 80% of it's capacity, less premature failure is eminant, and if one does load a circuit with a constant 95% it won't be enough to trip the breaker, but will be enough to eventually damage the breaker, thus it may not be able to trip when it needs to. It is kinda the un-written rule that one can't push electrical at it's maximum limit continuously or you may damage the protection device itself]

So we'd be on thin ice to say it's "ok" to use this product so long as we don't use it at the amperage ratings that either are approved for the product (drawing 20A on a 20A breaker, for example), or so long as there is never an overcurrent (drawing more than 20A) at which you are going to depend on the breaker to do its job - trip.

Doug Comments: Made me LOL. (laugh out loud) Yeah that would be like saying it works fine so long as it's not asked to do the very thing it was built to do. Good one

Daniel Comments: so we agree, that it would be ridiculous to assert that the Zinsco problems are occuring only because the equipment is being mis-used.

DF original note continues: those concerns stated, my review first will address whether we're inaccurately stating what advice home inspectors should give to consumers. I certainly agree that this particular failure has not been as deeply studied as the FPE problem.

[In my personal opinion i think there just needs to be a little wiggle room, for the way things are now the Inspectors pretty much have to condemn the panel, even if it is operating in a light-duty enviroment as it was intended. Lets face it. Aluminum tends to be a light duty product, that seems to preform well under light duty applications, so the panels work fine in many applications, but that point wasn't ever made. That was all i was getting at]

Doug commented: In closing it's not un-usual to find top grade, bolt in style breakers, in commercial boxes burn out at the high grade copper bussbars, but the problem is usually somebody not obeying the 20% rule, and i might add the breakers, lines, and damage tend to look just like the one in your photo of the Zinsco, yet these were high grade commercial boxes doing the same thing, which was why i questioned this from the start.

I was kinda wondering what people were doing to this Zinsco panel to cause this to happen. Is it the panel or the people? Hope this helps you in some odd way. LOL

Daniel comments: in sum, it is a faulty argument to blame equipment failures on mis-use when the failure occurs dramatically more often in one brand or product than among its similar competitors.



Doug H. to D Friedman:

Hi Dan,

Local person says: "Your GTE-Sylvania-Zinsco electrical panel has an aluminum bussbar, thus was a nice affordable panel in it's day, for light duty usage, such as dwellings that are plumbed with natural gas. It has preformed well and will continue to preform well in your natural gas home, so long as future tenants don't convert the high-demand appliances over to electric."

This is in no way to be mis-construed as to saying the product is safe or not safe, for most everything can be abused, but the years of un-interupted service at your home and other's homes do seem to say the product preforms as it should when used properly, however if continually over-loaded with high-demand usage, then failure is naturally going to occur, which has been documented on the following website"

Here's the problem.

Home Inspectors are 'not' writing these electrical panels up as preforming less than competitors, but instead writing them up as being a fire hazards and making them be replaced to pass inspection, then quoting your websight as their basis.

Now I understand what you are doing. Trying to educate and protect the public. Which is a good and worthy thing. Plus a thankless job for the most part. So may I thank you up front for all you do to make the world a better place.

Ok now. I'm all for nice modern 200 amp panels with copper bussbars, and personally think all breakers should be of the bolt in style to prevent loose connections that normally cause the burn outs, but the probem is these Zinsco panels were an affordable, light duty box, for low-cost housing, thus many are out there, and have preformed well when used for there intended purpose, but your article doesn't give that side of the story.

Basically the Zinsco panel isn't a grade 'A' panel, but neither do I believe it is an 'F' panel as the inspectors seem to say, and no where on your site is there anyway to show the inspectors the other side the story, thus many poor people in affordable housing are being forced to upgrade to brand new expensive 200 amp copper bussbar electrical panels that they can't afford, even though they already have a 200 amp aluminum bussbar panel that has preformed well in their dwelling just as it was intended to do under light duty usage that their all gas home provides.

Somehow, unless the product has a high failure rate under the designed usage, then both sides of the story need to be given on the product, which your sight doesn't seem to do.

Maybe you need to say it preforms well under light duty usage, but with the aluminum buss bar has a high failure rate under modern high-demand loads such as electric heat, electric oven, electric hot tub, thus panel should be upgraded before converting to these high-demand type appliances.

And i've seen the photos on your websight, but that breaker was obviously rode hard for a long time to make the wires burn back and all that damage. This wasn't a quick burn or a light load. Something is usually pulling allot of power for a long time to cause that kinda look.

Anyways sorry this is so long, and i like your websight, but it just isn't 'un-biased' as education is supposed to be, thus inspectors are using it as a way to force new expensive electrical panels onto people.

I'm not sure i worded this right, but i hope you grasp the point of giving both sides the story, so as people can make a good decision based on the level of their living, rather than a 200 amp, copper bussbar, electrical panel just be forced on everybody, do to one sided websites.

With Sincerity, Doug

From: Daniel Friedman
To: 'Doug H'
Sent: Thursday, October 29, 2009 3:03 PM
Subject: RE: Zinsco and Zinsco-Sylvania circuit breakers

Thank you for your note, it is an important one and a fair question to ask.

To be clear, we are not comparing Zinsco residential equipment with commercial or other special-grade items, but rather to all of the other residential grade equipment in the marketplace, regardless of bus design or materials. With the exception of FPE Stab-Lok, which performs worse and has been more thoroughly studied, there are only infinitesimally few field reports of the kind of bus and breaker burn-ups among other residential products like those reports we receive from electricians, home inspectors, home owners, and builders for Zinsco.

By no means do we suggest that a replacement 200A panel is a requirement where service ampacity requirements are adequatge at lower levels, nor have we specified a requirement for a copper bus panel - not for low income people nor anyone else - the electrical panel size and ampacity are chosen based on the actual building load and usage according to well documented procedures.

The panel ampacity or panel size has nothing to do with the Zinsco question - a product by the way that appears in a range of ampacities itself. It would be a misrepresentation of our information to suggest that we make any such perscription, and if there is text anywhere in our content that is confusing on that point, we would be pleased to correct it.

We will review our text to make sure that this point of view is clear to our readers.

But with the present data on Zinsco - you can readily read the field reports and see the failure photos for yourself and see reports of Zinsco faiures at 2500 times greater than typically experienced in the industry - an informed professional cannot claim that a Zinsco panel offers the same level of overcurrent protection that is afforded by its competitors priced in the same range and of the same panel ampacity.

Daniel Friedman

From: Doug H
Sent: Thursday, October 29, 2009 11:20 AM
To: Daniel Friedman

Subject: Zinsco and Zinsco-Sylvania circuit breakers

RE: Zinsco and Zinsco-Sylvania circuit breakers of the design described here do not offer the level of overcurrent and fire protection provided by most other electrical panels and circuit breakers. This means homes with this equipment are at greater risk of fire or other electrical hazard.

Yes, this is true, but those boxes are 'not' designed for heavy duty use. They are a cost affordable box for 'residentual' usage where electrical demand is normal, meaning they work well in moderate homes, that are 'not' all-electric, thus don't have electric heat, electric ovens, electric water heaters, electric hot tubs, and other hi-demand devices.

You need to add to your article this 'fact' and state they are perfectly safe when properly used.

This may be America, but we can't all afford a nice 200 amp, copper buss panel now can we, but your article forces low-income people to put such expensive things into their moderate homes before they can sell them now don't you?

Your article is 'not' un-biased.
It does 'not' offer both pros and cons.
It is 'not' a just article.
It should 'not' be used by home inspectors.

With sincerity, Doug

More Zinsco Advice

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 see ZINSCO FAILURE REPORT PROCEDURE to homeowners when a Zinsco Sylvania™ electrical panel is observed by a contractor, home inspector, or electrician.

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 anecdotal evidence. See ZINSCO FAILURE PHOTOGRAPHS and ZINSCO FAILURE REPORTS.

Repair advice (replace the equipment) is provided at ZINSCO REPLACEMENT PANELS and at REPAIR ELECTRICIANS we list electricians who have informed us that they have specific experience with this equipment. Lots of other licensed electricians are also qualified to replace electrical panels; it's best if your electrician is one who is familiar with this issue.

To the best of our knowledge, replacement of this electrical equipment is not required by law, or building code, but it is recommended by experts who are familiar with the occurence of field failures with this product. As described at ZINSCO FAILURE REPORT PROCEDURE, based on that experience and on actual field failure reports we strongly recommend that the electrical panel be replaced.

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 ZINSCO FAILURE REPORTS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


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