I am aware it is illegal, and I know the reason is that it leaves one wire hot when the circuit dies. Someone not realizing that could easily contact the live wire. And I know that reason I can't do it for myself is that the next owner will not know about it. But if I swear on my Mother's grave that I will convert it to 120v before selling the house....
I have a bunch of extra 15a 120v breakers, but would have to buy a 15a 240v. As I see it, the circuit is open whenever either breaker is open. If the live wire somehow leaks to the ground wire, that will trip the other breaker. I just don't see any potential danger here. Am I overlooking something?