The general rule requires connecting the grounding terminal of a grounding-type receptacle and a metal box joined to an equipment grounding conductor employing an equipment bonding jumper sized per Table 250. Figure 1 shows how this general rule works. This Grounding Standard describes the technical requirements for grounding the SEC Distribution Network installations. SEC Distribution System extends from the MV (33 kV, 13. 8 kV) feeder outlets of HV / MV Substations down to SEC Customer interface including KWH-Meters and meter boxes. For commercial and industrial systems, the types of power sources generally fall into four broad categories: Utility Service: The system grounding is usually determined by the secondary winding configuration of the. Abstract: Discussed in this recommended practice is the system grounding of industrial and commercial power systems. The recommended practices in this document are intended to provide explanations of how electrical systems operate.