Key takeaways
- Federal Pacific Stab-Lok and Zinsco panels were installed widely from the 1950s into the 1980s, which covers a large share of San Antonio's mid-century housing stock.
- Both brands share the same core failure: a breaker that looks fine and stays on when it should trip, which removes the protection the panel exists to provide.
- The Consumer Product Safety Commission closed its Federal Pacific investigation in 1983 on resource grounds, not on a finding that the panels were safe. There was never a recall.
- Insurers treat both brands as an underwriting problem, and replacement is considered maintenance, so the cost falls on the homeowner rather than a claim.
There are two panel brands we look for the moment we open a panel door in an older San Antonio home. Federal Pacific Electric, usually branded Stab-Lok on the breakers, and Zinsco. Both were installed widely from the 1950s into the 1980s, which covers a large stretch of this city's housing stock, from the postwar neighborhoods on the northeast side to the 1970s subdivisions that filled in around them. Both have a documented history of the same failure, and both cause the same problem with insurance. Here is the straight version.
What is actually wrong with these panels?
A circuit breaker has one job. When current on a circuit exceeds what the wire behind it can safely carry, the breaker opens and cuts power. Everything else about a panel is housekeeping. If the breaker does not open, the wire keeps heating, and the protection you believe you have is not there.
That is the failure both brands are known for. Independent testing of Federal Pacific Stab-Lok breakers found failure-to-trip rates far above what the listing standard allows. Zinsco arrives at the same place by a different road: the breakers connect to an aluminum bus, that aluminum oxidizes and heats at the connection, and over years of expansion and contraction the connection degrades until the breaker can effectively weld itself to the bus. A welded breaker cannot trip. Worse, its handle can still be moved to off while the connection behind it stays live.
This is why we treat these panels differently from a panel that is merely old or merely full. A 1960s panel from a sound manufacturer that is undersized for a modern house is a capacity problem, and capacity problems announce themselves by tripping. These two are the opposite. The complaint we hear most about Federal Pacific and Zinsco panels is that they never trip, and the homeowner reads that as a good sign.
Was there ever a recall?
No, and the history matters because it is often told wrong in both directions. The Consumer Product Safety Commission investigated Federal Pacific Stab-Lok breakers and closed the investigation in 1983 without a recall. The closing statement is a resource decision, not a clean bill of health: the agency cited its budget and the cost and uncertainty of continuing, against other known hazards it also had to address. Nobody at the agency concluded the breakers were safe. They concluded the agency could not afford to finish proving they were not.
So when someone tells you there was never a recall, they are right. When they tell you that means the panel is fine, they are filling in a blank the record does not fill in.
How do I tell if I have one?
Federal Pacific panels usually carry the FPE or Federal Pacific Electric name on the panel label, and the breakers are marked Stab-Lok. The most recognizable tell is the breaker toggle: black, with a red or orange stripe across the top. Zinsco panels are branded Zinsco or, on later units, Sylvania-Zinsco or GTE-Sylvania, and the breakers commonly have colorful markings on the toggles rather than the uniform look of a modern panel.
The identification is straightforward for an electrician and it takes a few minutes. What we would ask you not to do is pull the panel cover off yourself to look. The cover is the last thing between you and the service conductors, which are live even with the main breaker off. Read the label on the door, take a photo of the breaker faces if you can do it without opening anything, and let someone qualified confirm the rest.
An electrical inspection is the clean way to settle it. We identify the panel and breakers, check the bus and the connections for heat damage, and give you a written report with photos instead of a verbal opinion at the truck.
Why does my insurance company care so much?
Because carriers underwrite on loss history, and these two brands sit on the list of things that correlate with electrical fires. In practice that means a Texas homeowner with one of these panels can be declined on a new policy, or renewed once and then nonrenewed, or asked to document that the panel has been replaced by a licensed electrician within a set window.
The part that catches people off guard is the money. Insurance covers sudden, accidental loss. Replacing a panel that has not failed yet is maintenance, and maintenance is the homeowner's cost. So the carrier can create the deadline without paying for the work.
If you have already received a letter about it, the sequence and your options are worth understanding before you start calling contractors. We wrote that up separately in what it means when your insurer flags your wiring.
What does replacing one of these panels involve?
It is a service change, not a box swap. The new panel has to be sized to the home's real load, the grounding and bonding brought to current code, the branch circuits landed and labeled correctly, and the work permitted and inspected. In San Antonio the city has adopted the 2023 National Electrical Code, and the electrical permit is pulled by a registered contractor, not by you.
There is a utility step too. Replacing a panel usually means the power comes off at the meter and goes back on afterward, which is coordinated work with CPS Energy. That coordination is part of the job, and it is one of the reasons a panel replacement is a scheduled full day rather than an afternoon.
The cost drivers are the same ones that move any service change: where the panel and meter sit, whether the meter can and mast come along with it, and the state of the grounding. We broke those down in what a panel upgrade costs in San Antonio, and we handle the work itself as a panel upgrade.
Is there any reason to wait?
One honest reason, and it is a scheduling reason rather than a safety one. If you are already planning a service upgrade, an EV circuit, solar, or an addition inside the next year, doing the panel once, at the right size, beats doing it twice. Tell us what is coming and we will size for it now.
What is not a reason to wait: the panel has never given you trouble. With these two brands specifically, an uneventful history is not evidence the protection works. It is the absence of a test.
We replace these panels across the metro, and they turn up most in the neighborhoods that were built out during their production run, from Windcrest and Kirby on the northeast side to established areas like Alamo Heights. Send us a photo of your panel label and we will tell you what you have.