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. Each DISTRIBUTION BOX and controller must be grounded. Grounding of the units: Attach a ground wire from one of. Grounding is a mechanism to protect distribution equipment and people under normal operating conditions, abnormal operational (overcurrent and overvoltage) responses, and hazardous conditions such as shocks. Whether you're a seasoned pro or just starting out, this comprehensive guide will give you practical. An earthing system (internationally ) or grounding system (US) connects specific parts of an electric power system, such as the conductive surfaces of equipment, with the ground for safety and functional purposes.