does a gfci need a ground to be effective?REPLACING A TWO PRONG OUTLET WITH A THREE PRONG GFCI
Nope, it will operate just fine in a ungrounded system. Although it has the word ground in it’s name it has nothing to do with the operation of the device itself. Also GFCI circuit breakers require a neutral connection to operate but not a ground.
A grounding-type receptacle without a ground is a safe installation as long as the GFCI protection circuitry within the device has not failed from shorts and voltage transients. To insure proper GFCI protection, test the GFCI monthly in accordance with the manufactures instructions and if the GFCI test does not operate properly, replace the GFCI protection device.
Read here for more information;
http://www.mikeholt.com/mojonewsarchive/All-HTML/HTML/GFCI-Receptacles-Without-Ground~19991230.php
When I test GFCI with an outside source they never trip if there is no ground. Why is this? How do I know for sure they are not a safety hazard? Any help with this would be valuable to me and many others with the same issue. I use the ideal circuit tester with the short cord. Can’t think of the item # right now.
The reason that it won’t trip is because of your testing method. If it’s a GFCI receptacle just press the TEST button. Your tester requires an EGC to cause the 4-6ma current imbalance which the GFCI circuitry will read. No EGC, no imbalance, therefore incorrect test results. Although it now appears that the GFCI device doesn’t work it may actually be working just fine.
Thank you Robert, is there a better method to test them? I have called them up before as defective and reported that they be replaced. If I just use the test button and they react properly I will mark them acceptable correct?
The Test button is the recommended way to properly test a GFCI.
Also if a GFCI is open ground it should be labeled “no equipment ground”
Do that with you night night (errrr 3-light tester) plugged in … 
Why must there always be a “better way” of doing things?
Is pushing the test button too sissified? Something that the homeowner could do just won’t cut it?
“Man-Up”! Put a 10d finish nail in the plug and stick your ***** (what-ever) in the sink of water!
** Just kidding! Don’t do this at home, leave it to the “experts”!
So what if you test the gfci outlet with the button on it, it works, but then you test the down stream outlets with the “night lite” but can’t get them to trip?
Simplest explanation would be that the downstream receptacle is ungrounded.
Trip the gfci with the test button and then check the downstream ones to see if they are off.
As posted; Stick your “body parts” in the plug and see what happens…
Push the button and see if the power turns off elsewhere.
What more do you want?
It don’t work with an external tester without a D a m n Ground.
AS POSTED.
You need one of NACHI’s letters advising that you need more damn training (like many of us got)…
Why are you asking us? We are not “NACHI Certified” these days.
If your not a moron CMI that has nothing to do but collect boyscout Merritt badges, you don’t qualify here.
But till they kick me out, I can still say stupid s h i t and advise the world that Burkson is as worthless pile of dog crap.
I’m ignoring the rest of that post as it adds nothing to the question.
I know it won’t “work with an external tester without a D a m n Ground”
What I’m saying is that with “a D a m n Ground”, if the down stream outlets don’t trip the GFCI how do you KNOW they’re protected.
Yes when the GFCI trips there’s no power but will a ground fault in those down stream outlets cause it to trip?
Good question. You could use a solenoid style tester (AKA Wiggy) and test from the hot to a good known ground. The imbalance of the current from the tester will trip the upstream GFCI. I sometimes use an extension cord plugged into a grounded receptacle or test to a grounded water pipe. A high impedance testing device like a digital multi-meter (DMM) won’t work in this test because the current imbalance imposed isn’t great enough to trip the GFCI.
If your 3-light tester indicated the non-gfci outlet is grounded, and you push the gfci test button on the 3-light but nothing trips it’s not protected.
Yes … a GFCI detects a difference between the hot and neutral wires. If there is fault and current starts flowing from the hot wire, it should detect the hot-neutral current difference and trip.
You know, when you do step# 1.