kosketusjännitteessä

Kosketusjännitteessä describes the potential difference that exists between two points on the surface of the Earth or within a conductive medium when a current flows through it. This phenomenon is particularly relevant in electrical safety, especially concerning ground faults and the operation of electrical grounding systems.

When an electrical fault occurs, such as a live wire coming into contact with a conductive object, current flows to the ground. This flow of current through the earth creates a voltage gradient, meaning the electrical potential is not uniform across the ground. The potential difference between any two points on the ground surface accessible to a person or animal is the touch voltage. If this voltage is sufficiently high, it can cause a dangerous current to flow through the body, leading to electric shock.

Factors influencing touch voltage include the magnitude of the fault current, the resistivity of the soil, the arrangement and size of grounding electrodes, and the distance between the points of contact. Safety measures like equipotential bonding, grounding grids, and overcurrent protection devices are designed to limit touch voltages to safe levels, thereby minimizing the risk of electrical injury. Understanding touch voltage is crucial for designing and maintaining safe electrical installations, particularly in areas with higher fault current risks, such as substations or industrial sites.