Many home electrical appliances use 220 volts; to ensure safety, they must connect their outer metal shells to the ground wire to be very good. Especially washing machines and refrigerators, when using, must comply with the above requirements.
There are many types of washing machines, and there are roller type, agitator type, water jet type, wave cake type, vibration pattern, etc. All washing machines come with electric motors and control circuits; they are all powered by electricity. Besides, when the washing machine operates, it must be exposed to a large amount of tap water, the working environment is relatively humid.
Everyone knows water is a conductor of electricity. A person who touches electrified water will cause electric shock. Suppose the electric motors or circuits in the washing machine are damp or otherwise cause their insulation performance to below. In that case, electrical leakage occurs, then the metal part of the washing machine outer case is charged, also can make metal drum and all kinds of mechanism to move, stir, roll and so on the metal in the washing machine is charged. At that time, the water in the washing bucket will also bring electricity. If the user’s hand reaches the drum, comes into contact with the water in it, or accidentally touches the metal outer casing of the washing machine, there is a possibility of an electric shock, which can be fatal.
Of course, before the factory was shipped, the manufacturer checked its electrical insulation performance. The insulation resistance between the live part and the non-live metal of the washing machine, in the state of water flushing or overflow, must be more than 1000 kilometers, sufficient to prevent electrical leaks, preventing the user from an electrifying jerk. But to prevent uncertainty, we still have to apply a simple electrical shock prevention measure to ground the washing machine.
After the washing machine is properly grounded, when an electrical leak occurs, the human body touches metal components that should not carry electricity and will also be safe. Because electricity has the property that it always chooses a path with small resistance, compared with the human body’s resistance, the resistance of the ground wire is much smaller, current will pass through the ground wire and into the ground.
For the ground wire to be truly protective, it must be well connected to the ground, and its resistance should not be greater than 4 ohms.
Refrigerators are similar to washing machines, often exposed to frozen water or water, and relatively humid operating environment. The refrigerators’ compressor and control circuits are also likely to leak, causing the metal part of the refrigerator’s exterior to carry electricity. Therefore, to prevent uncertainties, the refrigerator’s metal outer shell must also be perfectly connected to the ground wire.
Household electrical appliances with a metal outer shell such as microwave oven, air conditioner, rice cooker, ventilation fan, electric kettle, electric heater, fan, etc., also pay attention to the good ground connection. Also, like listening to equipment, television, stereo, video, etc. Since the machine’s power passes through an electronic circuit that is completely isolated from the cabinet, there may be no need to connect the ground wire.