I was having a talk with an acquaintance who claims to be a licensed electrician (also claims to be a "master electrician", whatever that means.) I distinctly remember reading somewhere that a GFCI receptacle can be installed in house wiring where there is no ground wire. I can't remember where I read that, so I couldn't prove it to him. The books we looked at (the ones available in the home store where I bumped into him) all show grounding in the examples of course. He insists grounding is required for GFCI to work.

I also asked him about how the GFCI mechanism works, and he seemed to have a complete misunderstanding of the fundamental principles involved, so I don't trust his other answer either. He seems to think it relies on rerouting unsafe current out to ground (basically the way any grounded device works). It seems to me that since the device monitors incoming current versus outgoing current in the device, a ground wire should have nothing to do with it working correctly.

I'd like to find a definitive answer to this though. It might be this passage in "Code Check Complete" (Taunton Press), but I wanted to make sure that by "equipment" they mean the GFCI receptacle itself, and not the thing you're plugging in.

"A GFCI will operate properly without an equipment ground. The receptacle should be labeled "no equipment ground" & any downstream protected receptacles should also have that label as well as a label stating that they are GFCI protected. Labels are not required for properly grounded GFCI-protected receptacles."

 

First of all, any "electrician" that talks about electricity being "rerouted to ground" is no electrician, regardless what licenses he may (or may not) have. Electricity is NEVER routed to ground although lightning strikes do travel from the earth to the clouds.

Ground Fault Circuit Interrupters DO compare the current flow on the "hot" and "neutral" conductors and IF there is a current imbalance of more than 6 milliamperes (0.006 amperes) the GFCI will cut the current flow. An equipment ground connection is NOT required for this function.

Code requires that any circuit that has GFCI but no equipment ground must be labeled as such. Some equipment, mostly electronic, requires an equipment ground for proper functioning of the equipment but not having the equipment ground has NO EFFECT on the working of the GFCI.