A couple of topics here got me to thinking some more about multiple services to a building.

Suppose you have a commercial building fed with 277/480V Wye. O.K, so perhaps in most cases there would be a customer-owned xfmr to get local 120/208 service, but what if the PoCo provides a separate 120/208V Wye (or a 1-ph 3-w 120/240V supply).

If the NEC requires neutral-ground bonding at each main panel, how does the PoCo feel about having the neutrals of two different services effectively connected together in this way?

In my experience, the power company enforces the grounding of the neutral at the building as part of their pre-energization tests, even when there is no other AHJ. In the un-inspected areas I have experienced, the PoCo lineman will make sure the neutral is bonded to ground before he runs the service lateral. . .anything else may well be ignored, but not that. I take that as evidence that the PoCo is all for the neutral ground bond even when it cross neutrals different systems.

Al

There really cannot be any true N isolation with the N&G practice used here, be it under one roof, or having a common municipal bond.

Yeah, that's pretty much what I was thinking from the recent posts on this.

I can see more of this discussion arising in the U.K. with the increasing use of PME (i.e. bonded N-G).

There has been, ROP's as i understand, as to a N-G separation back to the serving X-former. The NEC has dictated 'codes' for many other trades, but that seems to stop at the utilities, who seem impenetrable.

Something like the U.K. system in my diagram #1, you mean? I have to confess that I like that system a lot, although I wouldn't be adverse to installing a ground rod at each house as well, just to be certain.

What's ROP by the way?

Way off the subject, but we have a "Regional Occupational Program"(ROP) in the high schools here, which teaches mainly agricultural occupations.
Here in North Orange County, it is abbreviated as NO CROP

Scott, soundslike a federal program

Paul; http://www.nfpa.org/Codes/National_Electrical_CodeR__NEC/Proposals/necpdf/A250.PDF
ROP= Report on Proposal, anyone can write and submit one, but it usually needs to be of indisputable quailty to amount to an NEC change.

there are ROC's = Report on comments, where there are some points of views that are , at least in my opinion, real rippers. One individual's letter on the recent change of 'fixture' to 'lumiaire' eluded to plumbers mistakenly mounting toilets on kitchen cielings , absolute 5-star ripper!

Scott [electure],

Haven't heard about NOCROP for years!!! I learned Diesel Mechanics in 1982-3 at Loara High School in a NOCROP program.
Give me a call sometime

As to this thread;

I have seen a few PoCo supplied systems / services as described. Seems to me that the whole thing would be as any other type of "Dual Services" or even SDS [Separately Derived System] would be - as far as the Grounding / Grounding Electrode System is concerned.

Just my thoughts.

Scott SET.