With the massive caveat that I don't have a first principles understanding of any of this: I don't thing any individual load in your oven takes both legs and th

With the massive caveat that I don't have a first principles understanding of any of this: I don't thing any individual load in your oven takes both legs and the neutral to do work. They're all either 120v or 208v single phase. Aside: a lot of motors can run on either 240v single phase or 208v single phase (or, presumably, anything in between?). Take a look at Grainger or McMaster-Carr.