Is the 3-phase being supplied from the PoCo pole in a wye or delta configuration? has there been any recent work by the PoCo on the pole with the transformers? There is a possibility that the transformer phases on the secondary side of the pole have been hooked up in correctly. This gives a 200v+ reading between the phases at the transformers, while still maintaining the 120v to ground. This does not explain the 0v volt reading between the A and C phases. Some more information is needed as to the type of 3-phase configuration and the setup.
(3 or 4 wire). In my opinion though, this is a PoCo problem. If you can get me some some more info, I will look into it more.
