My hot water heater is on a 30 amp double pole breaker, each wire runs to one of the elements. Any idea of the rating of each Pole? Is 15 amp pole plus 15 amp pole 30 amps? I have a Tranfer box with 2 20 amp poles, Tranfer box is rated for 30 amps so I guess what I'm asking is the double pole 20 amp each pole OK to handle the 30 amp, has #10 wire

Nope... a 30 amp dbl breaker has two indivifual 30 amp breakers. And you need a 30 amp breaker for #10 wire. What's the transfer box for?

Thanks for the info, I found a Reliance Tranfer switch 30 amp , with only 2 30 amp breakers already tied together. My whole house is on a Generator tranfer swith except the HW heater, this will be perfect for my needs.

Just how large of a generator are you using? (or small) Or should I ask how large is your house that a dbl. 30 pole breaker can handle it?