kosketusjännitteeltä

Kosketusjännite refers to the voltage that appears across a person's body when they touch an electrically energized object while simultaneously being in contact with an earthed surface. In electrical safety, understanding and mitigating kosketusjännite is crucial to prevent electric shock.

When an electrical fault occurs, such as a live wire coming into contact with the metal casing of an appliance, the casing can become energized. If a person then touches this energized casing and is also in contact with the ground, a path for current to flow through their body is established. The voltage difference between the energized object and the ground is the kosketusjännite. The magnitude of this voltage depends on factors like the fault current, the resistance of the earth connection, and the resistance of the person's body and footwear.

The danger of kosketusjännite lies in the current that flows through the body. Even relatively low voltages can cause significant current flow if the body's resistance is low. This current can disrupt the heart's rhythm, cause muscle contractions, and lead to severe injury or death. Electrical safety systems, such as residual current devices (RCDs) or ground fault circuit interrupters (GFCIs), are designed to detect such leakage currents and quickly interrupt the power supply, thereby limiting the duration and severity of exposure to kosketusjännite. Proper grounding of electrical installations is also a fundamental measure to reduce the risk by providing a low-resistance path for fault current, thus minimizing the voltage rise on conductive parts.