26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. Each DISTRIBUTION BOX and controller must be grounded. Grounding of the units: Attach a ground wire from one of. Safety of Personnel: By safely channeling fault currents into the ground, proper grounding helps to reduce the risk of electric shock to personnel. This helps to reduce the potential difference that exists between conductive parts and the earth. Grounding is needed for electric safety and it also creates a reference point in a circuit to. Knowledge of the various types of system grounding and performance characteristics is critical when designing or operating an electrical system. The topic of system grounding. In the US, grounding and bonding are regulated by the National Electrical Code (NEC), while in the UK and Europe, they are guided by standards issued by the International Electrotechnical Commission (IEC) and national regulations such as BS 7671 (IET Wiring Regulations).