This is because this water heater has two sets of electric heating, the first set is good. When you shift to the second gear, the second set of electric heating has destroyed the insulation to the ground, resulting in electric jump. You can measure the recombination with a multimeter or a shaking table. Electric heating must be right. It is recommended to replace and reorganize the electric heater, which costs tens of dollars. In this way, you have removed two sets of heating wires. The mark is wrapped. Plug it in again and try to jump. If you don't jump, the electric heater must be broken. If you jump, especially when you don't turn it on, the power cord is grounded. Use a multimeter to measure one pin of the plug and the housing, and test whether the other pin and the housing are connected. It shouldn't work. If it works, that's right. In this case, please replace the power cord and plug.