If this DIDN'T occur, anyone who touched the box or housing would get a shock - whether you've got a GFCI outlet is irrelevant.A GFCI outlet protects against a short (or more commonly a current leakage) involving YOU and an electrical device plugged into the outlet.You see, both two-prong and three-prong outlets have a hot and neutral wire.The hot wire carries electricity from your electrical panel to the outlet.The ungrounded outlets are easily distinguishable by their two slot configuration verses the newer grounded type of outlets that have the two slots with a hole (ground socket) centered under the slots.
Many ungrounded outlets have been installed in the older homes, but as the years went by the electrical standards have changed and are absolutely required in newer homes.
The neutral wire carries electricity from the outlet back to the electrical panel.
But here’s where they differ: a 3-prong outlet has an additional, 3rd “ground” wire whereas a 2-prong outlet doesn’t.
I've been remodeling an upstairs bedroom in a 100-year old house.
The electrical outlets are all ungrounded; the wiring only has two wires and no conduit.
I've read that as an alternate to re-wiring your entire house to get more protection (and a 3-prong adapter) at your outlets, you can safely (and under code) just replace each outlet with a GFCI outlet (or a central GFCI, I suppose). What level of safety does it provide using a GFCI on an ungrounded circuit versus a grounded circuit?