Sparky:
Looks like no one wants to touch this topic.
There are "quite a few" 3 wire sub-panels floating around here in NJ, and we are a stste that has had inspections for a long time.
I can't find any documentation to either support or refute the situation.
In 21 years I know that any sub-panel that we installed was 4 wire for single phase, and five wire for 3 phase/4 wire. It was always "hot/hot/neutral/ground" or"h/h/h/n/g"
Another "old-timer" favorite used to be the "bare" neutral for the service. Never was fond of that either. Kind of goes with the "undersized neutral" school of thought. I have a tough time trying to figure the economics of having 3-500 MCM feeders, and a 250 MCM neutral. Yes, it's great if the majority of the connected load is 3 phase stuff, but why in an office bldg., or a resi complex?? Seems to me that it's more of a pain in the axx to have two sizes of wire.
But, that's my personal humble opinion.
Hey, if you read this soon...Happy New Year, and be safe.
John
