In short, the answer is YES. An ungrounded GFCI-protected receptacle will still provide the required protection. In other words, you can connect a GFCI outlet on an ungrounded circuit.
Read below to learn more.
What happens if a GFCI does not have a ground?
A GFCI-protected receptacle does not have to be grounded in order to provide protection against a ground fault.
In other words, a GFCI that is not grounded can still prevent someone from being electrocuted in the event of a ground fault.
Why does an ungrounded GFCI-protected outlet not trip when I test it with a GFCI tester?
A GFCI tester such as the one shown below uses the ground wire connected to the receptacle to set up a “fake” ground fault in order to test the GFCI (to see if it will trip).
On a grounded GFCI, when you push the test button on your GFCI tester, a partial short circuit between the hot wire and the ground wire is created. This causes a small amount of electrical current to flow from the hot wire and through the ground wire.
The GFCI will detect a difference in the amount of current that is flowing through the hot wire and the current that is flowing through the neutral wire. This difference in current will cause the GFCI to trip.
On an ungrounded GFCI, there is no ground wire to create this fake ground fault, so the GFCI will not trip. If you don’t understand the concept explained above, you may think that you have a faulty GFCI when you actually have a properly functioning GFCI outlet.
The built-in test button will allow you to test the proper functioning of the GFCI – even on an ungrounded receptacle. Just push the test button and listen for the click.
If you have a tester like that shown above, you can plug it in and make sure the light on the tester goes off when you push the built-in test button on the outlet. If the light goes off, then your GFCI is working just fine.
© 2023 Mike Morgan
This article was written by Mike Morgan, the owner of Morgan Inspection Services. Morgan Inspection Services has been providing home, septic and well inspection services throughout the central Texas area since 2002. He can be reached at 325-998-4663 or at mike@morganinspectionservices.com. No article, or portion thereof, may be reproduced or copied without prior written consent of Mike Morgan.
