CNC Dan
Veteran Member
I see three black wires entering the box. One is a ground and goes to a wire nut, allong with a bare copper wire that goes to the box screw, and another short black wire that goes to the outlet ground connection.well I see both hot wires from the outlet connecting to a single incoming wire. In other words there's two outlets connected on with one incoming wire so is three wires under one wire nut. There's no way in the world you can have 240 that way I'm not sure how you're reading it.
The other two black wires go to the remaining outlet connections, as they should.
I would try turning the breaker off and on a few times. Or check the connections at the outlet and circuit breaker. A lose connection can pass enough current to get a voltmeter reading, but not enough to feed your welder.