[LazyPup]

I am sure that Hayzee will be able to give us much more detail on this, but back in the 50's & 60's it was common to install a non-grounded 220v line by only running two conductors, both of which were hot.

if you have a 40/40 breaker it may not have the required bonding clip across the trip handles, but whenever two breakers are placed side by side they are on opposite legs which would provide 220v.

A double pole breaker is basically two single pole breakers sharing a common housing and the trip handles are bonded together so that if either leg trips it will also trip the opposite leg.