Millions of U.S. and Canadian homes were built with circuit breaker panels that one expert has questioned as a potential fire hazard. Issues about Federal Pacific Electric’s “Stab-Lok” circuit breakers were first raised with the Consumer Product Safety Commission decades ago. The CPSC closed its investigation of the breakers in 1983 because, it said, the data available to the commission at that time did not establish “that the circuit breakers pose a serious threat of injury to consumers.” In an updated 2011 CPSC news release, however, the commission clarified that the investigation was closed “without making a determination as to the safety of FPE circuit breakers or the accuracy of the manufacturer’s position on the matter.” Now, a man who played a key role in identifying issues with FPE breakers is back with a new claim that Stab-Lok breakers made by other brands may pose a fire hazard as well, and is strongly urging homeowners to replace ­all Stab-Lok-type panels and breakers.