The metal box of the distribution box, the electrical installation board, and the metal base and casing of the electrical appliances in the box must be grounded. The protective neutral wire should be reliably connected through the terminal board. 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. Which NEC rules apply to electrical cabinet doors? Let's unpack a few key standards that apply: NEC 250. 28 (Box Materials): Metal boxes. Here are the steps on how to ground a power distribution box: 1. Preparation: First, you need to prepare some necessary tools, including grounding wire, grounding rod, voltmeter, insulating gloves and insulating tools. Avoid installing in a humid and corrosive environment to prevent equipment damage.