I have a question concerning the typical operation of the elements in an electric hot water heater. A typical heater has dual elements, each element being rated at 4500 Watts. From what I have been able to determine (research on the Internet) a 30 amp 240 volt circuit is the typical circuit required to power an average size water heater. A 30 amp, 240 volt circuit would provide 7200 watts of power. What is the sequence of operation of the dual elements to keep from over loading a 30 amp circuit. The above information is all assumptions. Would someone please give me a good explanation of how the heater operates electrically?