I think the problem is going to be more difficult to fix. If you are reading 115V on each leg to ground, but 0V line to line, then whatever is feeding these lines is on the same phase. Is your distribution panel single phase? I have one of those in my house, why they chose to do this I do not know, but a single hot wire is fed in and jumped to the other phase. This box in my house is full, and runs only receptacles so it doesn't impact me, but if I were to try to do what you have, I would have the same results.