Chico Home Inspector – Zinsco Electrical Panel

Probably one of the least favorite issues for a home buyer’s Real Estate Agent to read in an inspection report is anything about a Zinsco Breaker Panel. I have seen more than one cringe during a re-cap when the buyer was present and I mentioned “we do have a Zinsco Elecrtical Panel.”

So what is the issue with these electrical panels?


Zinsco was originally the West Coast division of the Frank Adam Electric Company, whose main facility was in St Louis, Missouri, the company became independent as the Zinsmeyer Company following the onset of the Great Depression. The younger Zinsmeyer took over the company from his father in 1943 and renamed it Zinsco.

The company was sold in 1973 to GTE-Sylvania, who continued to manufacture breakers and panels to the original Zinsco design for some years; this product line is now discontinued.


A typical vertical Zinsco sub panel

Zinsco electrical equipment is considered obsolete, due to a design flaw in which the circuit breaker’s connection to the bus bar becomes loose, causing arcing and subsequent overheating. Long term exposure to this heat can cause the breaker to fuse to the bus bar, making it impossible to remove. Even worse, it can cause the breaker’s contacts to fuse together, thus preventing the breaker from tripping even in an overcurrent situation, thereby causing a potential fire hazard.

Aftermarket replacements for the Zinsco breakers are available; however, it may be more cost effective simply to replace the entire panel with a more modern and safer design from another manufacturer (such as Eaton, GE, Siemens, or Square-D), depending on the number of breakers to be replaced. If the bus bar shows signs of corrosion, or if any of the breakers show signs of overheating, the panel should be replaced entirely. Many electricians advocate replacement of the panel in any case, due to its historically poor reliability.

Other Variants:

This is a Zinsco Panel “re-branded” as GTE Sylvania.

In 1973 Zinsco was sold to GTE – Sylvania which continued manufacturing the electrical panels and breakers using the same designs (and flaws).

As such, you may see a “generic” Zinsco warning on an inspection even if the panel has a GTE or GTE Sylvania sticker on it.

As you can see here, when this breaker was removed from the panel the aluminum bus bar shows significant damage from arching. This damage can not be seen by simply looking at the panel with the cover off.

Why your inspector can’t say the Zinsco panel in a home is “safe”.

The majority of the issues with Zinsco breaker panels are internal and / or hidden unless each breaker is removed and inspected. Not only does this go beyond the typical home inspection, removing the breakers from a Zinsco panel can contribute to future bus bar issues.

Is this a deal killer?

Absolutely not! Replacing a main or sub panel is not inexpensive, but when looking at the total cost of a home purchase or sale the cost is very inconsequential and an improvement to safety that will last the life of the home.

Choosing the right home inspector can be difficult. Unlike most professionals you hire, you probably won’t meet me until your inspection appointment--after you've hired me. Furthermore, different inspectors have varying qualifications, equipment, experience, reporting methods, and pricing.

One thing that’s certain is that a home inspection requires a lot of work. Ultimately, a thorough inspection depends heavily on the individual inspector’s effort. If you honor me by permitting me to inspect your new home, I guarantee that I will give you my very best effort.

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