As what JValdes saying but let me add one more thing is check the poco supply sometime they will supply the open delta format or open wye so check out the can[s] if you see just two cans both not same size that is open delta but if you see 3 cans if two are same and third one is diffrent that genrally it is delta but some case they used same size all the way thru with cans so watch for secondary taps that is surefire hint the first and third can will have no netural hook up at all but if this is on underground service the bet is off due the transformer set up.
What ya have to do is go back to the main panel and check the voltage on main breaker to make sure you have straght 240 v delta some case you will run into corner grouned delta [ not the case if ya have 4 wire service ]
Merci, Marc
