What type of grounding electrode is required if the only available grounding electrode is a metal underground water pipe?

The correct answer for the required type of grounding electrode when the only available grounding electrode is a metal underground water pipe is a ground rod. Metal underground water pipes are considered effective grounding electrodes in electrical installations, as they can provide a low-resistance path to ground. However, the recommendation to supplement with a ground rod arises from the need to ensure redundancy and compliance with grounding requirements.

A ground rod serves as an additional grounding electrode that can enhance the grounding system's reliability. It is especially useful in situations where the water pipe alone might not provide sufficient grounding due to corrosion or other factors. By using a ground rod in conjunction with the metal underground water pipe, the system can achieve better grounding performance, which is critical for safety and equipment protection.

The other options, such as a concrete-encased electrode or steel reinforcing bar, while effective grounding methods in certain applications, are not specifically related to the condition of relying solely on a metal underground water pipe. A Ufer ground is a form of grounding using concrete encasement, but it would not be applicable when the only available option is a metal water pipe.

In this case, the logical approach is to utilize a ground rod as an additional grounding measure alongside the existing water pipe, ensuring compliance with grounding and