Did you use you little tester or did you use the test button on the Plug.
All directions say to use the test button on the plug That little hand held tester will not work on a two wire system .
That is correct and just the basis that a GFCI senses the difference between amps or current and not ground should help you to see no ground is needed.
Ok, I get it. Yes Roy I did use the test button on my suretest. How can we be sure they will trip from an outside source? Does the test button create the .005 miliamp differance? Not trying to be difficult just making sure I understand it so I can explain it to a client correctly.
You need to carry a ground wire with you to test it with your tester 20 feet of wire with two alligator clips should be enough . You can pick up a yest ground from any tap or metal Heating vent .
This is really more then you as a home Inspector should be doing .
Use the Test button on the GFCI plug or just tell them it should be upgraded by a qualified person.
Great thanks Roy. I believe you are correct about it being beyond the scope.
A gfi doesn’t actually test for a ground fault. It measures the current on the hot and neutral and trips if they are not the same. The test button bypasses the measuring device with the neutral and adds a 5 ma load. It’s a better test because it doesn’t rely on the fault to return on any particular ground. Its sufficient that it just isn’t on the neutral. We aren’t allowed to connect anything from a conductor to ground, so CSA probably wouldn’t pass a device that produced an actual ground fault.
Simply put…
The GFCI simply measures current incoming on the hot wire and compares it to the returning current on the neutral wire. If there is more current going out than coming back, it assumes it’s going to ground and opens the circuit.
Thank you for the explanation Jeff. That has to be the best explanation I have seen. I now fully understand it and can easily explain that to a client.:):)
No problem Greg! 
This is exactly the frustration I have with this allowance. I have had many GFCIs over the years not trip on an outside source but the test button does trip them. How can a test button be better? I don’t trust them(the test buttons) so I’m uncomfortable not being able to test them with an outside source, but how could I recommend that they be upgraded if the NEC allows for an ungrounded GFCI?
Uh, that’s a video on how to push the test button and then reset it. Is that the video you meant to link to?
Yes you said you do not trust the test buttons .
( How can a test button be better? I don’t trust them(the test buttons) so I’m uncomfortable not being able to test them with an outside source, but how could I recommend that they be upgraded if the NEC allows for an ungrounded GFCI? )
Thanks Roy Now I understand how GFCIs work.
OK, Next question. Should we be using a tester that does not work in all situations. It seem to me we should be just using the tester that does not have a test button for the GFCI as the literature seems to say that the builtin test button is the only test that is needed. If this be true then the tester button is redundant and only works if there is a ground. The light read out will tell you that.
Thanks Roy Now I understand how GFCIs work.
OK, Next question. Should we be using a tester that does not work in all situations. It seems to me we should be just using the tester that does not have a test button because the GFCI as the literature seems to say that the built-in test button is the only test that is needed. If this be true then the tester button is redundant and only works if there is a ground.
The light read out will tell if the ground is open.
No because then you could not test the first one in series. This one should be close to the panel and have a proper new grounded GFCI. Any one after this should not be tested for GFCI function with hand tester and only be checked for proper wiring. Hot and neutral.
If you find another one in series there is no problem if it has no ground.
There is one exception and that is when they are not in series with one grounded GFCI.
The Manufactures that I have read say the test button is the proper way to test them . I used the little red tester and if it did not trip then I went to the GFCI button .
The little red tester also told me if it a two wire or two wire with ground system .
The built-in test button is the proper method of testing .
Mine is black but still the same.
I come back to my original issue which is I have had them not trip with an outside tester and then trip using the button on the outlet.
Is that then considered a safe GFCI?
If not then the button is not an adequate test.
YES
The Manufactures that I have read say the test button is the proper way to test them .
The built-in test button is the proper method of testing .