Jadnashua
Retired Defense Industry Engineer xxx
Remember, the magic to this protection is having the same current on both the hot and the neutral. WHen you give it a second path, that will rarely be the case, and the GFCI will trip. It only needs to be 5ma variation between what goes out on the hot that must return on the neutral to trip the thing. Nothing's absolute, but it will be safer. If you want it as safe as possible, tear the wiring out or abandon it and run new with a functional ground, but a GFCI gets pretty close. Some things, like common mode noise suppression and surge protection wants that grounded connector. While a surge suppressor will still offer some protection (neutral-hot, but not neutral-ground or hot-ground paths), it's still better than nothing.
