Which of the following is crucial for safety when dealing with electrical installations?

Proper grounding is indeed crucial for safety when dealing with electrical installations. Grounding provides a path for electricity to flow safely into the earth in the event of a fault. This minimizes the risk of electrical shock to individuals working on or near electrical systems. It also helps to stabilize voltage levels by providing a reference point, which is essential for the proper functioning of electrical devices. By ensuring that electrical systems are correctly grounded, the risk of fires, equipment damage, and personal injury is significantly reduced.

In comparison, while personal protective equipment, voltage selection, and load calculation are also important for safety and functionality, they play different roles within the overall electrical system. Personal protective equipment is essential for individual safety but does not address the system's grounding needs. Voltage selection must be appropriate to avoid equipment damage and ensure safety but relies on effective grounding to manage potential overloads or faults. Load calculation ensures that circuits are adequately designed to handle expected usage, yet it too must be accompanied by proper grounding to ensure overall safety in operation.