The electric water heater shows that the leakage protection is turned on when the water is cut off. Power failure of water heater is leakage protection, and equipment leakage leads to power failure of leakage switch. Water heater refers to a device that changes the temperature of cold water into hot water in a certain period of time through various physical principles. According to different principles, it can be divided into electric water heaters, gas water heaters, solar water heaters, magnetic water heaters, air water heaters and so on. A complete household multifunctional water heater consists of two main parts: the refrigerating gas part and the heating water part, which are closely related.