Rod and pipe grounding electrodes shall not be less than __________ in length.

The correct answer indicates that rod and pipe grounding electrodes must be a minimum of 8 feet in length. This requirement is standard in electrical codes, as a grounding electrode that is at least 8 feet long is generally considered sufficient to ensure a good electrical connection with the earth. The length helps to provide a reliable ground path for fault currents and helps mitigate the risk of electric shock, equipment damage, and electrical fires.

The regulation reflects the need for effective grounding practices that enhance safety and system reliability. Grounding electrodes that meet or exceed this length are more likely to achieve adequate contact with the soil, which is essential for integrating a grounding system effectively. Therefore, installing electrodes with this minimum length helps ensure compliance with safety standards and is crucial for electrical systems' overall performance and protection.