It's not leakage, the power of the electrical appliance is high, which exceeds the load range of the switch or the switch is loose. Poor contact will cause heat and burn the switch. In this case, the protector will not trip. Change the switch with good quality and tighten the connector, because the water heater has high power, there will be electric sparks at the contact of the switch every time, and long-term ablation will lead to poor contact. Dude, if you change it yourself, be sure to turn off the main power. If you are satisfied, you will get points.