What is the purpose of a ground wire in electrical installations?

The purpose of a ground wire in electrical installations is to provide a safe path for fault current. When there is a fault in the electrical system, such as a short circuit or a malfunctioning device, excess current can flow through the ground wire. This grounding helps to ensure that any dangerous electrical energy is directed safely into the ground, thus preventing electric shock hazards and equipment damage. Grounding systems also improve overall electrical safety by stabilizing voltage levels and reducing the risk of electrical fires.

In contrast, the other options do not capture the true purpose of a ground wire. Increasing electrical voltage, controlling the flow of electricity, and measuring current are functions related to circuit design and operation rather than the protective role that grounding plays in safely managing fault currents in electrical systems.