• Good system grounding provides the path for normal load and fault currents while maintaining load and controls temporary overvoltage. Grounding is necessary to assure correct operation of electrical devices, to assure safety. First, we review and compare medium-voltage distribution-system grounding methods. We then analyze the behavior of ungrounded systems under ground fault. Power from factory ground must be installed by a qualified electrician. Each DISTRIBUTION BOX and controller must be grounded. 26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. Whether you're a seasoned pro or just starting out, this comprehensive guide will give you practical.