What is the minimum AWG size for an impedance grounding conductor made of aluminum?

The minimum American Wire Gauge (AWG) size for an impedance grounding conductor made of aluminum is indeed 6. This requirement is based on the National Electrical Code (NEC) guidelines, which dictate the appropriate sizing of grounding conductors to ensure safety and effectiveness in grounding systems.

Aluminum has different conductivity properties compared to copper, necessitating a larger wire size to carry the same current effectively. The NEC specifies that for grounding conductors, especially those used in impedance grounded systems, the size must be adequate to handle fault currents without excessive voltage drop or overheating.

Choosing a grounding conductor that is too small can lead to unsafe conditions during a fault condition. A size of 6 AWG aluminum ensures that the grounding system will have a low impedance path to ground, facilitating the proper operation of overcurrent devices and helping to prevent electrical shock hazards.

Other wire sizes such as 4, 8, or 10 AWG do not meet the NEC's prescribed requirements for aluminum grounding conductors when considering safety and system reliability in impedance grounding applications.