Warning

[mike31154]

GFI device will trip without having a ground as well. That's the whole premise behind it actually protecting us from shock. If you contact the hot lead of a GFI protected circuit & sufficient current leaks through your body to an external ground, like a wet floor, it will trip since some current is going through your body instead of back through the neutral wire. The GFI current threshold is so low that it will trip the circuit before the current through your body is enough to be harmful. This will happen whether there is a ground prong present on the electrical receptacle or not. It's also why it's acceptable (even advisable for personal protection) to replace an old two prong receptacle in older circuits using no ground wire with a 3 prong GFI receptacle. The ground prong in this case is not connected to anything, but the GFI can still protect you by sensing a current leak through you to another grounded surface. Hope that makes sense.