26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. 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. Grounding of the units: Attach a ground wire from one of. Abstract: System grounding considerations affect many aspects of an electrical system. However, high-impedance ground fault detection is difficult in multigrounded four-wire systems, in which the relay measures the ground fault current combined with the unbalance. Whether you're a seasoned pro or just starting out, this comprehensive guide will give you practical insights into proper grounding techniques, with a special focus on how selecting quality materials from a reliable building material supplier impacts your entire system's safety and longevity. It is not a final EPRI technical report. Copyright © 2017 Electric Power Research Institute, Inc.