Attach a ground wire from one of the threaded studs (A) at the bottom of the housing, to the mounting plate (B). The ground resistance between all system parts shall be <. 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. Grounding is necessary to assure correct operation of electrical devices, to assure safety. Power from factory ground must be installed by a qualified electrician. 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. Knowledge of the various types of system grounding and performance characteristics is critical when designing or operating an electrical system. The voltage, system arrangement, loads connected, and continuity of. IPMENT, STRUCTURES, ETC. IN ELECTRICAL STATIONS INCLUDING TRANSMISSION AND DISTRIBUTION SUBSTAT GR THAN 8 FT FROM THE FENCE. THE FENCE SHALL BE GROUNDED SEPARATELY FROM THE GRID UNLESS OTHERWISE NOTED ON THE A PROPRIATE PROJECT DRAWING.