In electrical systems, what is the primary purpose of a ground wire?

The primary purpose of a ground wire is to ensure safety by providing a path for fault currents. In an electrical system, if a fault occurs—such as a short circuit or a malfunction that causes a metal part of the system to become energized—the ground wire offers a low-resistance path for the excess current to flow safely to the ground. This helps to prevent electric shock, fire hazards, and equipment damage by enabling circuit breakers or fuses to detect the fault and disconnect the power supply quickly.

Unlike other options, which focus on functions that are not directly related to safety, the ground wire's role is crucial in protecting both people and equipment from the dangers posed by faulty electrical currents. This safety mechanism is fundamental in electrical systems design and installation, ensuring that any potentially dangerous fault currents are effectively diverted away from users and sensitive equipment.