GFCI Question

[Jeff S. Vogan]

I cant find the past posts regarding this issue, but I am running in to this almost daily. A city in my area now does "occupancy inspections" which are basically safety inspections, on all real estate transactions before the city will turn the water on to the house. Nothing new, same stuff we have been pointing out for years, only now the sellers HAVE to fix the problems to complete the transaction. The city's inspection requires GFCI outlets for all recepticles on countertop areas in the kitchen, the bathroom, etc. My question is, many, many houses around here are older and have ungrounded electrical systems. The sellers are simply buying GFCI outlets and installing them in to the old 2-wire recepticles, and when I test them with my tester, they won't trip. Do they still provide GFCI protection, or is it simply being passed by the city without working properly? Sorry such a long, drawn out question!!!

[Bruce A. King]

GFCI's work fine without a ground. Your tester uses a ground so it will not test, just use the test button on the outlet.

[Michael R. Boyett]

Yes, they are providing GFCI protection. A GFCI works by measuring the current balance between the Hot and Neutral wires and tripping if there is an imbalance of 5ma more or less. A ground is not required for the GFCI to operate but the outlet should be labeled "No Eqpt Gnd Present" to show the user that the Ground pin is not connected to Ground. Unfortunately, our little handheld GFCI testers simulate a ground fault using the Ground pin, which again is not connected, so that's why it won't trip the GFCI. Test it using the integral Test button and it should trip the GFCI. (Bruce beat me to it... )

[Allen L. Catterton]

Let me begin by stating that I was not an electrician in a past trade but I have a good understanding and training to run general tests and be able to call out defects in the system.

What I am hearing is that if a GFCI installed with 2 wire cabling, without a ground, functions properly as a safety device.

My question is, if an appliance or device (such as a hair dryer) has a 2 pin polarized plug, (with one of the male prongs being larger than the other) then the GFCI will disengage properly if there is a short in the appliance, creating an imbalance in the system. Is this correct?

Secondly, if a home is wired with 2 wire cabling, (no ground wire), has GFCI’s installed and the appliance plug has a ground pin, (3 prong plug) then the appliance is not grounded. Is it considered a safety defect if the outlets are not labeled to reflect this?

Thanks

[Speedy Petey]

My question is, if an appliance or device (such as a hair dryer) has a 2 pin polarized plug, (with one of the male prongs being larger than the other) then the GFCI will disengage properly if there is a short in the appliance, creating an imbalance in the system. Is this correct?[/quote]No. A GFI will NOT usually trip on a short circuit. A short is a line to neutral, or line to ground fault yes, but it is NOT a ground fault that the device is looking for.
A GFI monitors current in and out if there is any imbalance between what is coming in and what is going out the device trips. A short circuit is not this type of fault.
If there is an imbalance tehn the current must be going somewhere, but not enough to trip a circuit breaker. With this type of fault the GFI can only assume the current imbalance is going through you so it trips. A nuisance trip is when it is not going through you.

Originally Posted by acatterton

Secondly, if a home is wired with 2 wire cabling, (no ground wire), has GFCI’s installed and the appliance plug has a ground pin, (3 prong plug) then the appliance is not grounded. Is it considered a safety defect if the outlets are not labeled to reflect this?

Yes, it is considered a "safety defect" only if the receptacles in question are not labeled.