Apparently during World War II, Zinsco switched from using copper bus bars to aluminum, and that did not always work out.
This is just a public service announcement that what you see in a given Zinsco panel may not be the original bus bar. There are copper replacements available:
A Legacy (Replacement) Replacement Busbar for Type R & Q 125 AMP, 12/24 Circuit Zinsco Electrical Panels, part number SKU: UBIZRBK12 from Connecticut Electric Inc.
The CE UBI line also includes replacement wire-in-wire out and busbar based Zinsco breakers, newly manufactured and ETL tested to UL489 standards just like any other residential branch breaker. These are available a HomeDepot, Lowes, etc.
This is more about apartment buildings that might have 50x or 100x the panels you have in a single family house, combined with modest loads, no budget, and no history of problems over time.
And realize that the worst breakers on that chart are not FPE, not Zinsco, and in fact sold at supply houses and home depot regularly to this day. You might take out an old reliable Zinsco and get a modern breaker that performs worse. Private message me if you want a key to the article (IEEE rules mean the study authors could not name the vendors involved). Trust me you’ve heard of the vendors I speak of.
Fuses were so much less problematic in this way. They just can’t jam up, even if the case gets distorted.
Insurance will often accept retrofits in my area. Unfortunately the insurance company rules are inconsistent, shifting, and absolutely capable of taking a working performing panel and replacing it with an enshitified or fake new product that performs worse, introducing new vulnerability.
I was not attempting to ignite the insurance issue, just to make people aware that calling out a zinsco as having an aluminum busbar may be factually incorrect. Do what you want with the information.
I’ve heard about this and remember going down a rabbit hole years ago wondering if maybe the panels didn’t all need to be replaced. In the end, by now they’re past the useful life of any panel and we’re on solid ground recommending replacement.
The sad reality is that even if a reasonable fix exists the contractors want the bigger dollars of a full replacement so recommending anything less is an uphill battle. And this goes far beyond just electric panels.
Tin coated, which is how copper is made compatible with either copper or aluminum conductors. You can see the same thing in split bolts, T-Taps, H-Taps, and various other dual rated connectors (CU*AL).
I had a case where the problem was main fuses were replaced with the a cheap modern breaker, that then did not match the needed calculations for the rest of the system. What a mess – they ended up needing to replace the entire service for the multifamily building. Some old things DO NOT need to be replaced, and you’re buying off more trouble than benefit. Finding the line is… hard… defending that line can be even harder. A lot of the old equipment – not all – is way more solid and better built than today’s enshitified versions.
Good to know, but I wonder how the average labor cost of the parts replacement compares with the cost of panel replacement and not to mention, all the other benefits of panel replacement?
True. The commonly heard life expectancy of a forty years for service panels and components seems more directed at creating work than identifying a problem, but maybe I am too cynical. One the other hand, some old panels that worked just fine in their “youth” have not aged so well.
Marc: And fuses are less than 1%. And Murray is the worst of the pack, worse than Federal Pacific’s post 1960 product. Let’s debate fuse and breaker safety in another thread. Here I was just trying to make a PSA about the copper vs. aluminum bus bars.
I worked for a property management company in East Tennessee and multiple units had Zinsco panels in them. At the time the property manager was looking for a similar option to retrofit the current panels, even though I had recommended a complete replacement. In my professional opinion, zinsco or not , it’s risky retrofitting a panel and if you’re gonna spend that kind of time and money, you should just replace it.
@earmada3
It’s risky messing with any building system that’s performing. The chance of nicking a wire, creating a new place for screws to penetrate a wire, the risk of the work itself, and of course the cost. It’s a tradeoff for each decision maker to make. With newer Federal Pacific Breakers (not the original factory, but later in the production cycle) we have very clear evidence backed up by objective tests, of the friction jamming issue. With the other brands the evidence is anecdotal and paper thin. With fuses we have strong evidence of the lack of aging effects and continued reliable operation to and past the century mark.
Note that NFPA70B, and the technical manual of many of the breaker suppliers, mandates yearly cycling of the breaker to reduce the risk of future friction failure and to distribute the internal lubrication. With the bad FPE breakers, apparently, they get worse if exercised.
