Energy, High energy, Power systems

Step voltage: what is it?

How a lighting can kill many animals at the same time? The answer is step voltage and the explanation of this phenomena is the post’s subject.

The step voltage phenomena

When a lighting hit a point on Earth, an electric potential is generated on this point. The voltage on soil goes down when its further away from the point where the lighting hit, due to current dissipation. The electric voltage in a point, produced by a lighting, can reach millions of volts, more than enough to break soil’s dielectric, by that, transform it a conductor.

When each one of a person’s feet touch different spots close to impact point, the person suffers a step voltage, because will have a potential difference between the legs, consequently, will have a high current that can be fatal. On four-legged animals, the effect is even greater, therefore, they will have a greater potential difference. Source:

The electric current produced by step voltage is more dangerous to four-legged animals than to two-legged ones. Because this current can pass through vital organs on four-legged animals, while on people, current only passes through bottom part.

step voltage
The soil also can be electrified by a broken wire from transmission line, or by a fault current that passes through a tower or substation to the soil. Source: Electrical Engineering Portal.
birds on wire
Birds on electric wires don’t get electrocuted, because its claws are on the same electric potential. Source: Lucas Kukel.

Protection measures

  • Walk with short steps in risk areas to minimize potential difference between the legs.
  • During storms, people and animals must stay far away from trees, because there is considerable probability of lighting hit the trees.
  • Some risk areas have a grounding metallic mesh (Malha metálica) inside the soil, to minimize potential difference between different distances. Technical standards for implementation must be followed.
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About Pedro Ney Stroski

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