There is no power supply on the surface of the appliance, so there can be no current.

Mainly to prevent static electricity. Electrostatic contact with human body will produce instantaneous current, which will do some harm to human body. As for the specific damage, it depends on the amount of static electricity. This kind of situation is often encountered in daily life, especially when the weather is dry, two people will get an electric shock when they touch each other. In addition, some metals with high friction will be charged with static electricity.

How did static electricity come from? There are two main situations. One is friction, friction between objects, friction between metal and air. Take off your sweater in winter and touch the handle of the car when it is dry. You'll feel an electric shock.

The other is that the electric field will also form static electricity, mainly household appliances, which has a high probability of forming static electricity.

When the electric field is formed, the potential is high and the potential is low. No matter whether the high or low part passes through air or other contact, some charges will be lost, so that the surface of household appliances will be charged with static electricity when the electric field disappears. The grounding wire is used to release static electricity in time.