26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. On the US market, a 5. Each DISTRIBUTION BOX and controller must be grounded. Grounding of the units: Attach a ground wire from one of. Today, we're diving deep into the world of distribution box grounding, breaking down the standards, and shining a light on those sneaky mistakes that even experienced electricians sometimes make. The neutral conductor is typically the grounded conductor connected to the system's neutral point, carrying current under normal operation. Key Words - Grounding, Earthing, Safety, Surge Protec-tion, NESC, Neutral-to-Earth Voltage, Ground Currents, Stray Voltage.