Panels & wiring
Federal Pacific, Zinsco and Challenger: the three panels we will not add breakers to
Why we quote these as a replacement instead of doing the cheap thing you asked for.
Somebody calls because they want two more circuits for a finished basement. We open the panel, and it is a Federal Pacific Stab-Lok. Now we are having a different conversation than the one they wanted, and it is worth explaining why.
A circuit breaker has one job. When current exceeds what the wire in the wall can carry, it opens. Everything else about your electrical system assumes that this happens. Federal Pacific Stab-Lok breakers, along with Zinsco and Challenger, have a long-documented record of failing to trip under overload — sometimes jamming in the on position entirely. A breaker that does not trip is not a degraded component. It is the removal of the only thing standing between an overloaded conductor and the framing around it.
The second problem is that there is no upgrade path. Modern AFCI and GFCI breakers — the ones code now requires across most of a house — are not manufactured for these panels. Even the replacement standard breakers you can find are usually old stock or third-party units of uncertain provenance. There is no way to bring one of these panels to current protection standards while it stays on the wall.
What we do instead is quote the panel as a replacement, with the grounding electrode system verified, code-required AFCI and GFCI protection, a typed circuit directory, and the permit and inspection handled. You get the two basement circuits as well. It costs more than adding two breakers. It is also the only version of the job that is honest.
If you want to know what you have: the panel door has a brand label, and you can photograph it without removing anything. Do not take the cover off — the conductors feeding the main lugs stay live with the main breaker off.