What is the purpose of a counterpoise in grounding systems?

The purpose of a counterpoise in grounding systems is to help ground a structure by providing an additional return path for electrical currents. This is particularly important in situations where driven ground rods may not be effective, such as in sandy or rocky soils with poor conductivity. A counterpoise typically consists of a network of conductors placed either on or just below the surface of the ground, forming a low-resistance path that can help dissipate fault currents safely into the earth. By doing so, it enhances the overall grounding effectiveness, helping to protect both people and equipment from electrical faults.

In contrast, while a wire or grid above ground could potentially serve as a shock prevention measure, it does not directly fulfill the counterpoise's primary role in anchoring the electrical system to the ground. Similarly, a device that enhances electrical insulation or a protective cover for electrical equipment serves different functions unrelated to grounding. Therefore, option B accurately captures the core function of a counterpoise in these systems.