Journeyman Electrician Practice Exam

Which of the following grounding electrodes is not suitable as an effective ground-fault current path?

1. Metal water pipe

2. Building steel

3. Concrete-encased electrode

4. The earth

The correct answer is: The earth

The earth is not considered a suitable grounding electrode for effective ground-fault current paths because it does not provide a low-impedance path back to the source of supply, which is essential for the reliable operation of overcurrent devices and for personnel safety. While grounding systems rely on the earth to disperse excess electric charge from lightning strikes or similar phenomena, the earth itself does not have the properties needed to ensure a proper and instant conduction of ground-fault currents. In contrast, other grounding electrodes like metal water pipes, building steel, and concrete-encased electrodes all provide a direct and reliable path for fault currents to enable the protection mechanisms, such as circuit breakers, to function effectively. These materials also have lower resistance, making them more effective at quickly dissipating fault currents compared to the earth, which can have higher resistance and can be impacted by moisture levels and soil conditions.