Zinsco, Stab-Lok and Federal Pacific: What's the issue? 

Why has almost every insurance company taken a stance against Federal Pacific Stab-Lok circuit breakers? Short answer: They are known for starting fires. But you can protect your property from a potential loss by identifying whether your facility has Stab-Lok panels and replacing them with safer equipment.

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The Backstory

Federal Pacific Electric Co. manufactured many types of electrical systems over the years, and not all FPE equipment had problems. However, the circuit breaker panels marketed as Stab-Lok did have problems. Popular from the 1950s to the 1980s, they were installed in many commercial and residential buildings, and many can still be found today.

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The primary issue was the inability of the breakers to trip in an overload or short circuit condition. This failure would allow the excess current to heat up and start fires within the circuit, resulting in loss of property or loss of life. In a 1982 Securities and Exchange Commission Filing, Reliance Electric Co. (the parent company to FPE), documented “a possible defect” in their Stab-Lok breakers and acknowledged that Underwriters Laboratories approval had been obtained “through the use of deceptive and improper practices.” In fact, Underwriters Laboratories ended up revoking their UL Listing for those products manufactured by FPE.