Ungrounded Ground-Fault Receptacles

"Is there any benefit to installing a GFCI outlet to an older circuit that has no ground wire?"

A GFCI (ground-fault circuit interrupter) reduces the risk of electrocution by constantly measuring & comparing the current coming in on the hot wire with the current going out on the neutral. Any difference in the current means that electricity is flowing back to the source on some path other than the neutral wire. That other path may be through your body to the ground, & that is what a GFCI is designed to prevent.

A GFCI works as well without an equipment grounding conductor (ground) as far as preventing electrocution, But beware of using computers or other electronics on this ungrounded circuit, however. GFCI will protect people from shock, but will not protect equipment from lightning/ spike damage even with a surge protector & electronics also use the ground to dissipate static charge.

Any outlets downstream of an ungrounded GFCI outlets that have ground slots should also be labeled "no equipment ground".

Posted by John Goad on 02/21/2008 05:39 AM

Comments (8)

gfci, groundfault receptacle, electrical, electrical repair

8 Comments on Ungrounded Ground-Fault Receptacles

FEB

2008

Thanks for the great piece of advice, I wasn't aware of this. Are you able to test to see if a GFI has a ground wire? Thanks for the posting.

I didn't know this either. I wonder how many of my computers and big items have no ground wire.

If your home was built in the last 30-40 years more than likely you have a ground wire, however, there could also be other contributing factors that could leave a circuit with an open ground. If you want to be sure you can get a 3 light plug in tester for 5-10 dollars at the hardware store to check the circuit. If your house is older than 40 years & the tester shows a grounded circuit I would recommend remover one of the cover plates & double checking for a ground wire, people have been known to run a jumper from the neutral to the ground on the outlet which will give a correct reading on the outlet, but in actuality is a false ground.

John, I would just add that the GFCI receptacle itself should also be labeled "no ground"

That was what I meant by saying they should "also" be labeled no equipment ground, but after rereading it I can see where that was not clear. Thanks for the feedback.

John, the English language is funny like that. Re-reading what you wrote it can be taken either way. I find myself being "caught" in those kinds of word issues all of the time.

OCT

Does the current NEC require GFCI protection at a marina shore power, twist lock outlet?

DEC

Good post, John. Regards,

Leave a response…

Name:

Email:
(optional)

Comment:

What does the graphic say?