I really don't know of any way of checking. I know that some utility companies require the high leg to be C phase in the meter. In the panelboards,

B phase gets the extra bracing so putting the high leg anywhere else could be a problem.

Looking at my oldest code book (1978) 384-3(f) "...The B phase shall be that phase having a higher voltage to ground."

Few things are harder to put up with than the annoyance of a good example.