Tom,
I can't find the 7 years reference, but here is a quote from a study by Levition.
"The GFCI Circuit Breaker Field Study, sponsored by The Leviton Institute, reviewed data from 13,380 building inspections and found that 15 percent, on average, of GFCIs were inoperative when tested.he study looked at both GFCI circuit breakers and GFCI receptacles, and found similar failure rates for each. The data suggested that lightning strikes are one likely culprit in many inoperative GFCIs. The study found a much higher incidence of failure in areas where lightning is prevalent. In those regions, as many as 58.2 percent of GFCIs were found to be inoperative."
Note that the high failure rate in is areas where lighting is common. I assume that this is due to spikes damaging the electronics.
Don(resqcapt19)
