The secondary side is solidly grounded and connected with MV grounding. It is a 4-wire system and the LV neutral is multiple grounded at all cable terminations, at MV / LV substations, distribution pillars, and consumer locations. 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. Distribution transformers have DYn11 connections. If the. Safety of Personnel: By safely channeling fault currents into the ground, proper grounding helps to reduce the risk of electric shock to personnel. This helps to reduce the potential difference that exists between conductive parts and the earth. Equipment Protection: Grounding protects substation. A sub panel is a secondary distribution point that receives power from the main service panel, allowing for the extension of electrical service to a remote area of a building or a separate structure like a garage or shed.