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 <. In this video, we'll walk you through the process of wiring a home distribution box with a detailed connection diagram. This position is the connection point of the grounding wire in the. Some methods below can add a ground wire when changing from a two-prong to a three-prong outlet. Photos below show how to ground an outlet or a switch under various wiring conditions. 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. In your case, the main panel is the big (but not so big, more below) panel inside.