26 mm 2 (10 AWG) ground wire must be used, and in all other markets a 6 mm 2 must be used. The objective of these three grounding systems is identical regarding protection of people and equipment - mastery of insulation fault effects. The concept is a simple one: provide a path for ground current via a resistance that limits the current magnitude, and. Abstract: System grounding considerations affect many aspects of an electrical system. During fault conditions, low impedance results in high fault current flow, causing overcurrent protective. The first letter T of TT grounding power supply system indicates that the neutral point of the power system is directly grounded, and the second t indicates that the metal conductive part exposed by the load equipment is not connected with the live body, but directly connected with the ground.