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. 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. Grounding of the units: Attach a ground wire from one of. Sometimes if I have a 3 or 4-gang plastic nail-on switch box that has a bunch of NM cables, when I'm making up the box rather than using a big blue wire-nut for my grounds I'll separate the grounds into 2 groups and use red/tan wirenuts instead, especially if there's 2 circuits in the box. However, the key to. Here are the steps on how to ground a power distribution box: 1. Make sure all tools are intact to prevent accidents during the grounding.