Abstract: In an electrical construction, grounding refers to a work for connecting a part of an electrical circuit or electrical equipment to the ground using a conductor. Since the ground maintains approximately the same potential, circuit parts connected to the ground through a low-resistance conductor may be considered to have a uniform potential value, and a conductor connecting an electric device to the ground is called a grounding conductor or grounding wire. The grounding wire is used with an insulating coating formed on the wire for the purpose of safety in processing. In the underground, the grounding wire is used in the form of a bare wire without the insulation coating for the purpose of close contact with the ground. The grounding wire can be used as a single wire when the size is small, however, if the size becomes large, several strands of wires are twisted and used in the form of a stranded wire.

Abstract: Electrical equipment is grounded in order to suppress ground potential rise in a healthy phase due to a failure of a line in a distribution line, to reduce abnormal voltages or prevent the occurrence of abnormal voltages caused by lightning surges, etc., to operate a protective relay when a ground fault occurs, or the like. Grounding is installed by burying a grounding electrode such as a copper rod in the ground and connecting the electrical equipment to be protected with a grounding line, and at this time, a reference value of grounding resistance varies according to the equipment. When grounding electrical equipment such as lightning arresters and transformers, it is necessary to lower a grounding resistance value, but a problem occurs when installing grounding by digging a pit in an urban area to erect an electric pole in that it is difficult to lower the grounding resistance value since it is difficult to install grounding in parallel because roads are paved.