Which of the following is NOT a type of grounding electrode?

The correct answer is insulated conductor, as it does not serve the function of a grounding electrode. Grounding electrodes are specifically designed to connect the electrical system of a building to the earth, providing a safe pathway for electrical faults and surges.

Concrete-encased electrodes, ground rods, and direct burial electrodes all fulfill this purpose. A concrete-encased electrode is typically rebar or a grounding conductor embedded in concrete, effectively grounding the structure. Ground rods are metal rods driven into the ground to create an electrical connection with the earth. Direct burial electrodes are installed directly in the ground and serve to ground electrical systems.

In contrast, an insulated conductor is a wire or cable that has insulation to prevent electrical contact and does not function to ground an electrical system. Instead of providing a direct pathway to the earth, it serves as a safe conduit for electrical current when insulated. Thus, it does not qualify as a grounding electrode, which is why it is the correct answer to the question.