well one thing about the class 320 socket here in state of Wisconsin it have two verison either 320 [400 amp ] standard meter or we have 600 amp bolt on metering socket i don't have the website for other POCO for that one but my POCO do have one on the listing.

NJ_WVUGrad you may have to talk to the POCO for the listing of other approved meter socket sometime they do listed it

hope it help here

Merci , Marc

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