Moderator Post (s) for this thread: >Very strangebyHandyman on 12/10/2008
Wire size depends on Total amps on the circuit and how far away the heaters are from the panel. Breaker size also uses the same basic things also. As for your shortage in panel space,you can use a piggy-back breaker to give you more circuits. It has has two circuits that fit into one panel space. If you are still unsure consult your local IBEW contractor. Good Luck!!