A 5500W element like this - http://www.amazon.com/Camco-02963-Heater-Ripple-Element/dp/B000BPG4LI draws 23A at 240V, so wiring it through a 50A breaker (instead of a 30A) at the box won't change what current gets to the element, only the amperage at which the breaker overloads and trips.
Lots...