i may as well throw in the proverbial monkey wrench here that seems to follow your Q, (hey, it's for science fer chisssakes)
the poco would agree with you, where N & G exist as one uninsulated conductor
they'd have little reservation placing meters on steel track housing incorporating a common mettalic h2o supply, ph service, cable, or other mutual interconnections.
heck, within our own trades scope, we could run an unisulated N&G combo overhead areial triplex to an outbuilding 5' away via 250.32 couldn't we?, as long as that outbuilding had such bonded to an GEC.
i've always viewed those pad mounted x-formers close to buildings and within reach of meters with similar concern
section #1 of art 250 delve's into theoretical aspects here, with potential reparations...
C-H posted a great noodle pdf here
as to the grander scheme, those countries that do not include the evil noodle
have circumvented this problem completely, foriegn devils!, always getting a leg up on us eh?
[This message has been edited by sparky (edited 01-08-2004).]