A supplementary grounding electrode is required when the only grounding electrode available is _________.

A supplementary grounding electrode is required when the only grounding electrode available is _________.

• A. Building steel
• B. A concrete-encased electrode
• C. A ground ring
• D. A metal underground water pipe

Answer: (D)

The requirement for a supplementary grounding electrode is primarily focused on ensuring the reliability and effectiveness of the grounding system. When the only grounding electrode available is a metal underground water pipe, it is essential to install a supplementary grounding electrode due to potential concerns regarding the continuity and integrity of that connection over time. Metal underground water pipes can present risks related to corrosion, physical damage, or other factors that may degrade their electrical conductivity, particularly if they are not in continuous contact with the earth along their entire length. If the connection to the water pipe is compromised, the grounding may become ineffective, leading to safety hazards and electrical system malfunctions. By requiring a supplementary grounding electrode in such cases, the electrical system ensures a more dependable path for fault currents and enhances overall safety. Other grounding electrodes like building steel, a concrete-encased electrode, or a ground ring may offer greater reliability and effectiveness on their own, as they are typically set in a way that maintains a more consistent electrical connection to the ground. Hence, these options do not necessitate the same requirement for a supplementary grounding electrode.

The requirement for a supplementary grounding electrode is primarily focused on ensuring the reliability and effectiveness of the grounding system. When the only grounding electrode available is a metal underground water pipe, it is essential to install a supplementary grounding electrode due to potential concerns regarding the continuity and integrity of that connection over time.

Metal underground water pipes can present risks related to corrosion, physical damage, or other factors that may degrade their electrical conductivity, particularly if they are not in continuous contact with the earth along their entire length. If the connection to the water pipe is compromised, the grounding may become ineffective, leading to safety hazards and electrical system malfunctions. By requiring a supplementary grounding electrode in such cases, the electrical system ensures a more dependable path for fault currents and enhances overall safety.

Other grounding electrodes like building steel, a concrete-encased electrode, or a ground ring may offer greater reliability and effectiveness on their own, as they are typically set in a way that maintains a more consistent electrical connection to the ground. Hence, these options do not necessitate the same requirement for a supplementary grounding electrode.