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 <. Power from factory ground must be installed by a qualified electrician. 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. 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. Whether you're a seasoned pro or just starting out, this comprehensive guide will give you practical. The grounding system provides a low-impedance path for fault current and limits the voltage rise on the normally non-current-carrying metallic components of the electrical distribution system.