If I get sent back to this same house this week I am going to get the capacity of the tank and size of each element. It was not a large tank, probably about 50 gal. It is simply designed to have a fast recovery time; therefore both elements can be on at the same time. (I guess people who spend 250K for a house don't want cold showers!) Seams to me we could have run only one feed since these elements are wired in parallel. 50amp if the elements are 4500w each or a 60 amp feed if the elements are 5500w. I am going to guess that during rough-in the usual 30amp 240v water heater circuit was run, than the plumbers come and install a water heater with elements that can both be on at the same time. Therefore, boss says, to save time, install a second 30amp feed and j-box with the usual flex to heater connection.