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ZINSCO SYLVANIA ELECTRICAL PANELS
Here we describe the real hazards of multi wire branch circuits and single pole circuit breakers where FPE Stab-Lok® equipment is installed. We define "latent safety hazard." This document explains the latent electric shock and fire hazards associated with Federal Pacific Electric Stab-Lok® electric panels and circuit breakers. Federal Pacific Electric "Stab-Lok® " service panels and breakers are dangerous and can fail, leading to electrical fires. The problem is that some 240-Volt FPE circuit breakers and possibly also some 120-Volt units simply may not work.
Replacement FPE Stab-Lok® circuit breakers are unlikely to reduce the failure risk of this equipment. We recommend that residential FPE Stab-Lok® electrical panels be replaced entirely or the entire panel bus assembly be replaced, regardless of FPE model number or FPE year of manufacture. We do not sell circuit breakers nor any other products.
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Special Notice: Multiwire Branch Circuits - warning: to avoid overheating neutral wire and shock hazards involving multiwire branch circuits, it is important to assure that each of the individual circuits is on opposite poles (in the panel) from the other.
In most panels this is accomplished, in fact forced, by using a 240-V common-trip-tie breaker (ganged together switches) which forces individual circuits onto opposite poles. However in FPE panels, the panel bus design does not provide this assurance. -- Rex Cauldwell
See Multiwire Branch Electrical Circuits and Split-Wired Receptacles - Electrical Wiring Safety Requirements - Note this is background on multi-wire circuits and is not FPE specific except that since I recommend wiring these circuits with double pole breakers and double pole FPE breakers don't trip very well, it's an important concept.
It is possible that there are similar failures among single-pole (120V) breakers. At least one case of a single-pole 120-Volt FPE GFCI breaker which failed to trip has been reported.
Furthermore, simply purchasing new circuit breakers of the same type from the same manufacturer may not correct the problem. And only special FPE breakers fit in the FPE "Stab-Lok® " electric panel.
When this issue was examined in the early 1980's, FPE's opinion was that the chances of an overload occurring on only a single pole of a 240-volt breaker were very small. In our view there are some very common real-world examples where single-pole loading in a 240-volt breaker might include failures: multi-wire branch circuits and in electric clothes dryers where one of the heating elements shorts to the steel case of the dryer.
The circuit breakers do not directly cause an electrical fire. Some other failure must occur which in turn causes an overload of the circuit "protected" by the FPE breaker. When the breaker fails to trip in response to the overload it has failed to provide the protection intended, and a fire may result. That indirection is why we call this a "latent safety defect."
Why we call this a "latent safety defect" rather than just "hazardous" or "dangerous" needs more explanation. Unfortunately, some people who stand to face big costs grasp at fine distinctions about the failure mechanism in order to avoid facing the problem.
When a defect is itself likely to cause injury directly, such as live wires poking out of the wall by the bathroom sink, we call it a "hazard."
When a defect does not directly cause the injury or loss, such as a circuit breaker which may fail to trip when something else is causing an unsafe overcurrent, we call it a "latent safety defect.
Either way, it's still a problem that needs prompt attention.
Is this a linguistic debate or is it really an issue in the field? You bet it's an issue. Recently during an examination by a Maryland home inspector (citations 4,5 below) an FPE panel, was observed and flagged as a potential hazard which should be remedied. The property owner, concerned about his sale, complained and threatened to sue the inspector. This was not an isolated case.
We were able to provide the inspectors with referral to Dr. Jess Aronstein, an engineer in Poughkeepsie, New York, who in turn provided supporting documentation: reports on this problem, a bibliography, and a press release from FPE.
In another example of the dangers of this "latent safety defect," Dr. Aronstein reported that during a disturbance in a jail, a guard hit a gang-switch in an FPE "Stab-Lok® " load center in the cell block area. The breaker did not trip. Rather, it shorted to ground in the switch, blowing a hole in the cover plate. (Citations 6,7)
Building inspectors and renovators often face the discovery of a product which is potentially harmful, which should be replaced, but for which there is little public documentation to justify their position.
Disagreement among people affected by this issue means that it's necessary to be able to cite actual research and actual real-world fire and failure reports.
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