How is touch voltage defined?

Touch voltage is defined as the potential difference between a grounded metallic structure and a point on the earth's surface. This definition is crucial in the context of electrical safety, as it highlights the importance of grounding in preventing dangerous electrical shocks. When a person comes into contact with a metallic structure that is grounded, the touch voltage can indicate the risk of electric shock if there is a fault in the electrical system.

Understanding touch voltage is essential for ensuring safety in electrical installations, particularly in scenarios where equipment may become energized. By knowing that touch voltage is the potential difference relative to the earth's surface, electricians can evaluate the risks associated with various installations and implement necessary safety measures, such as using proper grounding techniques and ensuring that all equipment is safely bonded.

The other definitions do not adequately describe touch voltage. The notion of voltage difference between grounded objects or average potential on a live circuit doesn't capture the significance of how grounding systems can affect safety. Understanding the direct link between a grounded structure and the earth helps in assessing potential shock hazards effectively.