Two electrical panel brands worth knowing about

Most electrical panels are fine at any age. Two brands are not, and both were installed widely in Southern California during the postwar building boom, so we find them constantly in houses from the 1950s through the 1970s.

Federal Pacific Stab-Lok

Federal Pacific Electric sold Stab-Lok panels for decades. Testing later found that a meaningful proportion of the breakers failed to trip on overload. A breaker that does not trip leaves the wiring to heat up under a fault, which is exactly what breakers exist to prevent.

You identify them by the Federal Pacific or FPE name on the panel and by the distinctive breakers, usually with a thin red or orange stripe on the toggle.

Zinsco

Zinsco, later sold under the GTE-Sylvania name, has a different failure. The breakers connect to an aluminum bus bar, and the connection corrodes and overheats. The breaker can weld itself to the bus, at which point the handle moves but the circuit never opens. Burned bus bars behind the breakers are a common finding.

These often have colorful breaker handles, blue, green, red, in a panel labeled Zinsco or Sylvania.

What we do about it

We report the brand, note the condition of what is visible with the dead front cover off, and recommend evaluation by a licensed electrician. We do not declare the panel unsafe on brand alone, because a given panel may be working, and we cannot test whether an individual breaker will trip.

What we can report is physical evidence: heat discoloration on the bus, melted breaker bodies, aluminum branch wiring, double tapped breakers, missing knockouts, and oversized breakers protecting undersized wire. Those findings are independent of the brand and often decide the recommendation on their own.

The cost

Replacement parts for these panels are mostly aftermarket and their reliability is debated, so the usual recommendation is replacing the panel. A panel replacement in San Diego generally runs a few thousand dollars, more if the service is being upgraded from 100 to 200 amps, if the meter or the service drop has to be redone, or if the panel is being relocated. It requires a permit and an inspection, and the utility has to disconnect and reconnect.

Insurance is a practical reason people deal with these. Some carriers will not write a policy on a house with an FPE or Zinsco panel, or they price it accordingly. That comes up during escrow often enough that it is worth knowing before you are under contract.

Aluminum branch wiring

A related item from the same era. Between roughly 1965 and 1973, single strand aluminum was used for branch circuits in some houses. It expands, contracts and oxidizes at connections, which loosens terminations. Where we find it, the remedy is proper connectors at every device by an electrician familiar with the method.