vermilye wrote:
Part of the confusion of what capability is built into a GFCI is because the original design of a GFCI only detected the difference between the hot & neutral, but newer ones have a circuit added that detects ground/neutral faults. I don't remember the year this addition was made; I have a request at Mike Holt's forum that may provide an answer. If I get an answer, I'll post the information here.
Grounded neutral detection has been part of the UL specification for GFCIs since at least the 1993 edition of the spec, possibly longer. It is not a new thing at all.