How much surface area must a plate electrode have in direct contact with the earth?

The correct choice regarding the surface area required for a plate electrode in direct contact with the earth is based on the National Electrical Code (NEC) and other industry standards. A plate electrode must have a minimum surface area to ensure adequate grounding and bonding that can effectively dissipate fault currents and provide a safe pathway for electrical surges.

The minimum surface area of 2 square feet is sufficient for a plate electrode because it allows for proper electrical contact with the ground, which is essential in maintaining effective grounding systems. This size strikes a balance between providing enough contact area to achieve low resistance to earth ground while also being practical in terms of installation and material use.

In contrast, other options either fall short of this requirement or go beyond what's necessary for most applications, thus not aligning with typical standards for grounding practices. The specified minimum surface area requirement helps maintain safety and effectiveness in grounding systems.