step voltage

When lightning strikes, a voltage drop occurs in the ground that propagates in all directions from the point of impact of the lightning. This voltage drop depends on the magnitude of the impact current, the earth resistance and the distance from the impact location.

The voltage drop is a potential difference that propagates across the earth's surface and is greater the farther apart the earth points used to determine the potential. The potential difference can be determined per unit length and may well be several kilovolts per meter near the point of impact.

The step voltage is the voltage related to the step width of a human. The larger the step width, the higher; the smaller the step width, the smaller the potential difference between the two legs. When lightning strikes and the step size is large, the potential difference between the two legs flows down the human body. Therefore, a small step size is required during thunderstorms in order to avoid this potential equalization, which can be life-threatening.