·Ground Line, Null Line and Live Line
The earth is a good conductor. Ground line forms short-circuit connection with the earth through the buried electrode. Electricity transmission is a three-phase approach. There is a neutral wire, the current of it is zero when three-phase equilibrium, commonly known as "null line". Another feature of null line is that it short connect with ground line in the system total distribution input, the voltage is nearly zero. The voltage between three-phase line and null line is 220V, which can produce shock to human body, commonly known as "Line Wire." There are strict standards for installation and permutation of electrical wiring. It is very important to correctly assemble the ground line, null line and live line according to the standards.