Ground Current
Definition
The spread of lightning strike current outward through the soil from the grounded strike point, generating potential differences that can damage electrical equipment connected to grounded utilities and injure animals and people standing in the field.
- Mechanism
- Current spreads radially through soil from strike point
- Hazard
- Potential-difference injury to standing animals and people (step potential)
- Risk zone
- Decreases with distance from strike point, highest nearby
- Equipment risk
- Damages grounded electrical/utility equipment via surge
Common questions
How is ground current different from a direct lightning strike injury?+
A direct strike delivers current through the body itself. Ground current instead creates a voltage gradient across the soil, and a person or animal standing with legs apart bridges that gradient, taking a shock proportional to their stride length, often without ever being struck directly.
Why are livestock especially vulnerable to ground current?+
Four-legged animals have a longer stride between front and back feet than the distance between a human's two feet, so they intercept a larger potential difference. This is why lightning strikes near a field commonly kill several animals clustered together while leaving people nearby unharmed.
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