Proper grounding for electrical systems is very important for the safety of the linemen, cablemen, groundmen, and the public. Correct operation of protective devices is dependent on the grounding installation. The National Electrical Safety Code (ANSI-C2 Standard) specifies the grounding methods for electrical supply and communications facilities. The National Electrical Code (NFPA-70 Standard) specifies the grounding methods for all facilities that are within or on public or private buildings or other structures.

The grounded static wires for transmission lines and the grounded neutral wire for primary distribution circuits originate at substations. The static wires for transmission lines will normally originate and terminate at a substation. The substation may be located at a generating station.

The substation grounding system governs the proper functioning of the whole grounding installation and provides the means by which grounding currents are conducted to remote earth. It is very important that the substation ground have a low-ground resistance, adequate current-carrying capacity, and safety features for personnel. The substation grounding system normally consists of buried conductors and driven ground rods interconnected to form a continuous-grid network. The surface of the substation is usually covered with crushed rock or concrete to control the potential gradient when large currents are discharged to ground and to increase the contact resistance to the feet of personnel in the substation. Substation equipment should be connected to the ground grid with large conductors to minimize the grounding resistance and limit the potential between the equipment and the ground surface to a...