Grounding is electrical staff is familiar with electrical safety measures. And all kinds of electrical systems are in the earth, the earth is a conductor, electrical systems must be equipotential connection with the earth, in order to avoid it, and to the potential difference between the cause of all sorts of electrical hazards and ensure normal operation of the electric system. For equipotential earth or close to the earth potential, to make electrical connection with the earth, but there is no electrical connection terminals on the earth, for this to be buried in the earth surface grounding terminals and lead to ground reference potential to gain ground potential, which is called earth. Due to a number of European grounding electrodes with the earth connection resistance or grounding resistance, and have great potential, on its therefore connected to earth ground, such as the potential effect is not very ideal. Along with the progress of the electricity technology, the grounding assigned with a new concept, grounding is not only limited to the connection of the earth, and take the place of the earth conductor connected with potential for reference potential and earthing conductor. Syria by aircraft electrical system connection with metal fuselage, and like a car electrical system and metal body connection, a connection can be considered as equipotential connection, also can be considered with instead of the grounding conductor connection and implementation of the earth. It is not to earth potential as the reference potential and potential body or body as the reference potential, because of its connection for metal connection, the connection just a few milliohm resistance, so its equipotential effect is superior to the traditional connected to earth ground. Building of equipotential connection also played a connected with instead of the conductor of the earth and the ground, however, building electrical devices is always need to be connected to earth ground, otherwise such as lightning current and electrostatic charge will not discharge National People's Congress, its lead to electrical hazards will be eliminated. Of course with the earth grounding is not specifically to make artificial grounding connection, often said in the building electric installation grounding device by the grounding, grounding line and the mother of three parts, it is used to achieve the purpose of the electric system connected to the earth. Direct contact with the earth, realizes the electrical connection in the metal objects for grounding in some electrical grounding electrodes can be assigned to this function, such as for the system grounding, protective grounding or signal. Grounding device of earthing resistance value should be able to always meet the requirements of the electrical system grounding resistance of various electrical systems have their different grounding requirements, in terms of the shock of the power distribution system, for example, according to the type with type in dry places within TT system and the protection of the IT system grounding RA earthing resistance value should meet the requirements of the following two type respectively. Grounding device of the various components of should have enough cross section, the normal leakage current and the grounding fault current can safely pass on the part of the allowed minimum cross section, the material of grounding device and specifications in its environment should have quite resistant to mechanical damage, corrosion and other harmful affect the ability of the grounding device is outside of our country's traditional underground into a number of Angle steel or steel tube, artificial grounding, actually this is not the practice of the economic and reasonable, because the soil for this kind of steel grounding pole (including galvanized steel grounding) has corrosion effect, with the number of years is due to corrosion and failure, had to be set up.