Please see attached short video that explains how a GFCI works and how to test for proper function. I’m not sure if this came from you or someone else but I use it often for training purposes. As I’m sure you know GFCI measure the difference between feed and return wire – when 5 mA difference it will activate. The ground should not have anything to do with how well the GFCI functions. I would suggest that test will indicated as to whether the GFCI will function properly.
Thanks for the share TC!
