I inspected a house yesteday that had a few GFCI outlets in the kitchen and all the rest of thle outlets in the house were labeled as GFCI with no ground for equipment being used. My tester showed open ground & would not trip any GFCI device.
Ther were also a couple of 2 prong outlets in one bedroom. Is this just a way of converting the house from 2 prong to 3 prong & is it safe or meet code.
The house was built in 1956
Roy Drangstveit
It meets code, and it is better than replacing two prong with three prong outlets, but not the best. Take a couple of hours and watch this http://www.nachi.tv/episode53, BTW, your tester won’t trip the GFCI in this case because it uses the ground to create the short. You would have to test using the GFCI device buttons themselves (which is really the best way to test them anyway.)
Bad = replace 2 prong with 3 prong = violation and unsafe
Better = replace 2 prong with 3 prong GFCI/labels = acceptable by NEC and safer, but not great
Best = re-wire with appropriate romex = acceptable by NEC as well as appropriate.
A GFCI should still trip without a ground.
Not with the “traffic light” tester, it won’t, without a ground. Some guys plug the tester into an adaptor and run a seperate ground wire to something metallic and grounded when testing load side 3-prong receptacles that are served with a GFCI but not grounded.
From yesterday PM, this kitchen outlet, brand new 2007 construction, no ground, tester button useless, works with the built-in button. Somebody in sub-trades gets a slap to the head. 
Also, the AFCI breaker in the panel does NOT trip with the test button. Is that a faulty unit?
John Kogel
www.allsafehome.ca
Also kinda makes you wonder why they used all the mini’s with plenty of space left.
Jeff