26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. If you've ever found yourself scratching your head over whether that metal door on your distribution cabinet really needs a grounding wire, you're not alone. In factories, construction sites, and even commercial buildings, this question pops up all the time. Grounding of the units: Attach a ground wire from one of. When inspecting the interior of a stainless steel outdoor electrical box distribution box, pay attention to the copper or tin-plated terminals on the base plate or side walls. There is a hole enabling you to bolt it to an appropriate backpanel or enclosure stud. Preparation: First, you need to prepare some necessary tools, including grounding wire, grounding rod, voltmeter, insulating gloves and insulating tools. Make sure all tools are intact to prevent accidents during the grounding.