What are safety precautions intended for during work or testing?

Safety precautions during work or testing are primarily focused on ensuring the safety of personnel and equipment. The correct choice highlights the importance of isolation and grounding, which are critical measures to prevent electrical hazards. These precautions help in creating a safe working environment by ensuring that equipment is de-energized and that there are proper grounding practices in place to mitigate potential electrical shock or other related hazards.

By isolating systems and ensuring proper grounding, the risk of accidents during operation or maintenance is significantly reduced. This focus on safety is paramount in electrical work, where the potential for serious injuries is particularly high. The other options, while relevant to operational effectiveness in different contexts, do not specifically address the safety measures required during work or testing in a power substation environment.