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*Federal Pacific Electric "Stab-Lok" breakers

Federal Pacific Electric "Stab-Lok" service panels and breakers are a latent hazard and can fail, leading to electrical fires. The problem is that some double-pole (240-Volt) FPE circuit breakers and possibly also some single-pole units simply may not work. We also have reports that independent of the breaker problems, there have been panel and panel-bus fires and arcing failures in some equipment.

A latent hazard exists where FPE Stab-Lok circuit breakers continue in use. The hazard is worst for double-pole breakers. Published reports of actual tests that were performed indicate that under certain conditions it is possible for one leg of these circuits to attempt to trip the breaker, resulting in a jammed breaker which will afterward not trip under any load condition.

Some common household appliances are powered by a two-pole 240V circuit (protected by the type of breaker under discussion) but use two or more independent 120V sub-circuits inside the appliance. Two obvious cases are electric clothes dryers and ranges. If, for example, the low-heat (110V) heater in a dryer were to short to the dryer case, a serious over current would occur on one "leg" of the circuit.

Another wiring practice, using a single two-pole breaker to power a split circuit which uses a shared neutral, such as may be installed in kitchens in some areas, is nearly certain to have each leg of the circuit loaded independently and thus subject to single-leg overloading and subsequent breaker jamming. A breaker which jams and then fails to trip under this condition is a serious fire hazard.