26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. On the US market, a 5. • Good system grounding provides the path for normal load and fault currents while maintaining load and controls temporary overvoltage. Good equipment grounding ensures personnel safety. Most North American distribution systems have a neutral that acts as a return conductor and as an equipment. This subpart contains requirements for the grounding of electric systems, circuits, and equipment. Circuits are grounded to limit excessive voltage from lightning, transient surges, and unintentional contact with higher voltage lines, and to limit the voltage to ground during normal operation. Each DISTRIBUTION BOX and controller must be grounded.