Zinsco Electrical Panels
Updated: Apr 12, 2020
I was inspecting a well-built 1960’s home on Forbes Avenue in San Jose (before we all started to shelter in place) which was going great until I reached the main electrical panel. Darn it… A Zinsco…
What’s a Zinsco?
Zinsco or Zinsco-Sylvania is a brand of electrical panel that was commonly installed up to the early 1980's. Production was halted when design flaws were discovered. The deficiencies were serious enough to be considered both a fire and electrical shock risk. The design of the panel includes aluminum bus bars, which are subject to corrosion and overheating as energy demands increase. Bus bars are metal bars (typically copper) that are usually hidden and are what the breakers clip on to. Once a breaker becomes taxed and melts at the bus bar connection, the breaker may not be able to trip and power continues to energize the panel and associated downline circuits. At this point, the panel cannot be shut off manually and power is continued to be supplied to the panel until the service can be terminated or wires melt. It is estimated that 20% of Zinsco panels are damaged. Further evaluation by a licensed electrician to confirm the integrity of the system is recommended. Due to the age of these panels (and any other panels 50 or so years old) replacement may be prudent.
The issue with Zinsco panels is that they can look fine from the outside. You may hire an electrician to take off the panel cover (not something that you should do) and the breakers and wires all look good with no visible problems or scorch marks. However, the damage is usually out of view and hidden and in the area where the breaker connects to the bus bar. Some of the breakers may be welded to the bus bar and not be able to be removed at all. Some breakers will fall apart as they are removed since they have been subjected to high heat over time.
I don’t intend to be an alarmist, but if your electrical panel has even a one percent chance of being a hazard, it may be worth the peace of mind to have it looked over.
There are other panels that have been found to be problematic, including Federal Pacific. Try Googling “Is my electrical panel safe?” and you will get some good websites that will provide you with additional information.
See you soon!