Fairly sure IAEI used to sell a brown-and-white booklet on history of the NEC, with some very controversial early times with respect to system and equipment grounding. In bryan’s initial post—if the service is ungrounded 480V [or possibly even 240V] 3ø 3-wire, there used to be some “liberties” permitted with these circuits, before the nowadays well-understood need for limiting potential difference between enclosures and raceways [where first-fault overcurrent- device operation is not an issue.] I may be nuts talking about it, but that’s nothing new—the nuts part anyways.
