In article ,
Cydrome Leader wrote:
Well, technically, a GFCI device doesn't need a ground prong or a ground
to function. Notice I say GCFI devive, not receptacle. Take for instance
hair dryers or electric blankets these days. They have a GFCI module in
the plug, which is polarized, but not grounded.

On the other hand, if you're installing a GFCI outlet, they all have
ground prongs, and to not ground it would be improper. Downstream outlets
could be old receptacles with no ground prong, if you're doing some sort
of retrofit or hacky upgrade. I have no doubt both have been done by
people at home, but a real electrician would do the same might be a
different story. Anybody know what the NEC says about this?

Ummm... as I pointed out a week or so ago, the Consumer Products
Safety Commission *specifically* points out that you can use a GFCI
receptacle on a circuit which has no ground. It will protect its own
jacks, and any other outlets which are wired "downstream", against
ground faults.

This is an accepted and approved method for adding safety to a
two-wire circuit which has no ground wire accessible.

I agree, it's not as good a solution as re-wiring with a good
ground... but it's a lot better than leaving a two-wire circuit
without ground-fault protection!

The CPSC (and I believe the NEC) requires that any GFCI outlets which
don't have an actual ground, must be installed with a sticker which
says so, so that the user is aware that the ground prong is "open".