What is a possible material type for equipment grounding conductors?

Mineral insulated cable, particularly in a steel alloy type, is indeed a viable material for equipment grounding conductors. This type of cable is designed to provide both mechanical protection and electrical conductivity through its metal components. The steel alloy creates a robust and durable grounding system that is resistant to environmental factors, making it suitable for various applications where grounding integrity is crucial.

On the other hand, while copper is a standard choice for grounding conductors due to its excellent conductivity, the selection "solid copper only" does not account for the diversity of materials and configurations available for grounding. "AWG wire only" is too vague and does not specify the type of material, and "plastic coated wire" typically lacks the conductive qualities necessary for grounding. Therefore, mineral insulated cable stands out as an appropriate choice for this application.