Understanding Step and Touch Voltage Hazards
Step and touch voltages are the primary cause of electrical fatalities at high-voltage facilities. This article explains the physics of these hazards and the engineering measures used to mitigate them.
When a fault occurs at a high-voltage electrical facility, large amounts of current flow into the earth through the grounding system. This current creates voltage gradients in the soil that can be hazardous to personnel in the vicinity of the fault.
Step voltage is the voltage between two points on the earth's surface separated by one pace (approximately one meter), in the direction of maximum potential gradient. Touch voltage is the voltage between a grounded metallic structure and the surface of the earth at the point where a person is standing while touching the structure.