It is also very important to never forget that it is with almost with all certainty that you can get enough current to flow through the ground form one point of contact to another to trip a breaker. The NEC requires that when a single ground rod is driven that there is 25ohms or less resistance. If one applies that to an ungrounded delta where 2 lines go to ground in different locations in a facility us 25 ohms as an example of the L-L resistance to determine if enougn current will flow to trip a breaker, not. The resistance may very likely be much higher.
Remember that GF indicators of any type are worthless unless somebody is notified and that person has the qualifications to locate the failure.
