Grounding of the units: Attach a ground wire from one of the threaded studs (A) at the bottom of the housing, to the mounting plate (B). This helps to reduce the potential difference that exists between conductive parts and the earth. Equipment Protection: Grounding protects substation. 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. 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. The voltage, system arrangement, loads connected, and continuity of. Ground fault current magnitudes depend on the system grounding method.