......Experience has shown that voltage surges due to utility switching, lightning strikes or other transient phenomena were the cause of a good many failures of GFCIs and other electrical equipment. An interesting factor is that the surges responsible for damaging a GFCI also caused the GFCI to trip. The natural assumption that users were resetting these damaged GFCIs was considered. After a damaged GFCI was reset, power could be delivered without GFCI protection, just like an ordinary receptacle. Perhaps users were not testing their GFCIs after such an event, or if they were tested, the information was ignored. The natural tendency may have been for the user to assume that if the power returns, all is well......