. If you want more details just look up NEC art 555.72 {2005 editon }

it do allow triphase supply to used in larger RV parks and some POCO may limited the single phase supply to their transfomer size.

I know one RV park near me in Wisconsin do have triphase supply { the newer section of the park do have it the old section still on 1Ø supply but the transfomer is pretty big for our POCO 125 KW single can. you can imaged the size of secondary conductors blink

Merci,Marc

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)