The ground wire, also known as the lightning protection line, refers to the wire used to introduce current into the earth; when the electrical equipment leaks, the current enters the earth through the ground wire. The symbol of the ground line is E (Earth); it can be divided into two types: power supply ground and circuit ground.
According to China's current standards, the third line copper clad steel of GB2681 according to the color of the circuit, generally should be the phase line - A phase yellow, B phase green, C phase red. Zero line - light blue, ground line is yellow and green, if it is a three-hole socket, the left side is the zero line, the middle (top) is the ground line, and the right side is the fire line.
The longer of the three legs is grounded and can be called a grounding leg. The other two shorter legs are used to connect household appliances to the circuit, which can be called conductive feet. When designing the power plug, the grounding foot is intentionally designed to be several millimeters longer than the conductive leg in consideration of the safety of the user.
This is because when the three-pin plug is inserted, the grounding pin first contacts the grounding wire in the socket, so that the grounding protection can be formed first, and then the power is turned on; otherwise, when the three-pin plug is pulled out, the conductive pin first and the conductive terminal in the power socket Separate, disconnected after the grounding foot. If the metal casing of the household appliance is charged due to insulation damage, etc., the grounding pin will form a grounding short-circuit current, so that the metal casing of the household appliance is grounded and discharged to the ground, so that people are not subjected to electric shock and play a role of safety protection. .