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. 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. Here are the steps on how to ground a power distribution box: 1. Usage: Use this. The fiber distribution box, a crucial component in optical fiber networks, serves a dual purpose of managing and protecting optical fibers while facilitating their efficient distribution.