Re:ALL devices and connections to the same ground (Score 1)

Ground is shared by all 3 phases. I've measured between neutral & ground & hot & ground on each of the 3 available phases (at the outlet & breaker box) and all is well. The Home Depot circuit tester shows all ok as well. I have not used an oscilloscope on it, that may yield some interesting clues. I shall try that. (I'll have to haul my museum piece of an oscope into work for that one). Thanks.