26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. There are several factors that make substation grounding absolutely necessary. SEC Distribution System extends from the MV (33 kV, 13. Each DISTRIBUTION BOX and controller must be grounded. Grounding of the units: Attach a ground wire from one of. Abstract: System grounding considerations affect many aspects of an electrical system. We then analyze the behavior of ungrounded systems under ground fault. Grounding systems aren't just boxes and wires – they're the silent bodyguards protecting people and equipment from electrical disasters.