How is that accomplished without some sort of earth ground?
The equipment grounds are bonded to the grounded conductors at the service equipment which provides continuity back to the transformer but not to earth.
Understood.
So it getting it from the transformer which has an earth ground …hopefuly?
Ground rods and connections to a water pipe electrode having nothing to do with opening the OCPD when there is a ground fault. As Chuck stated this is accomplished solely by the connection of the EGC’s to the system neutral.
What is required for the receptacles to be grounded is an EGC back to the panel where the main bonding jumper connects the EGC’s to the neutral conductor.
I don’t think anyone was saying that was the right way to go, but it will provide continuity to ground from the ground socket of the receptacle and give a good reading on a three light tester. I’m not sure what you will get on a circuit analyzer, whether it will show as OK or a bootleg.
Check your equipment I had a bad tester. Ideal tester saved me from bad report.