How do you check a 240v 2 phase outlet?

Answer 1

There is no 2 phase outlet. Most outlets, including 240V such are your dryer or range in your house, are single phase. There are 3 phase outlets defined also. 2 phase is an obsolete system that was used in the early days of electric power before 3 phase was universally accepted.

That said, with a voltmeter you should have around 120V between each hot and neutral or ground, and 240V between the hots. Which plug is hot and neutral depends on what kind of outlet it is. See the source below for pictures. The neutral is labeled W (for white).

Answer 2

Phase to Phase with volt meter