What device is used to check if each line conductor is de-energized before installing protective grounds?

To ensure the safety of personnel when installing protective grounds, it is crucial to determine whether each line conductor is de-energized. The high-voltage voltmeter is designed to measure the presence of voltage in high-voltage systems, making it the appropriate device for this task. This tool is capable of safely detecting voltage levels and confirming that conductors are not carrying electrical current before work is undertaken.

Using a high-voltage voltmeter helps technicians avoid accidental shocks or injuries that could occur if a conductor is mistakenly thought to be de-energized when it is not. This is critical in high-voltage applications where standard testing equipment might not be adequate for the voltage levels present.

In contrast, while an ohmmeter is used for measuring resistance and could indicate continuity in a circuit, it does not provide a means for checking if a line conductor is energized. Similarly, a multimeter, though versatile and useful for various measurements, may not be suitable for high-voltage testing without appropriate settings or limitations. Finally, a clamp-on ground-resistance tester measures the resistance of grounding systems rather than determining the energization status of line conductors. Thus, the high-voltage voltmeter is the correct choice for ensuring electrical safety prior to work.