Why birds don’t get electrocuted on wires

The answer is found in the intriguing interaction between physics and biology. Let’s break down exactly what’s happening when a bird lands on a high-voltage wire.

Difference in electrical potential

Why birds don’t get shocked depends on a basic concept in electricity, which is, current only flows through a wire when there is a difference in electrical potential or voltage.

When a bird sits on a power line, both its feet make contact with the wire at the same electrical potential, which is at the same voltage level. There is no significant voltage difference between the points of contact with the bird, so little electrical current will pass through the bird. Birds don’t get electrocuted on power lines because they don’t complete an electrical circuit — they’re not providing a path for electricity to flow from high voltage to low voltage. Their small size, the short distance between their feet, and their isolation from the ground all work together to keep them safe.

If a bird touches both a power line and something grounded (like a utility pole, guy wire, or transformer), it creates the same dangerous situation humans face. (Source: Freepik)

Why humans get electrocuted differently

As humans, we face electrocution risks as  contact with electrical sources is usually accompanied by grounding, thereby establishing a path between the electrical source and the ground. This means persons can be touched by a high-voltage wire, pass the electricity through their bodies, and discharge it into the ground, which maintains the zero electrical potential. This high magnitude of potential difference constitutes a large amount of current flow through the human body, making it fatal.

When birds do get electrocuted

Unfortunately, birds can sometimes get electrocuted. This happens due to one or more of the following reasons: 

Touching multiple wires: If a large bird like an eagle or crane spreads its wings wide enough to simultaneously touch two different power lines carrying different voltages, it creates a path for current to flow between the wires through the bird’s body. This can be fatal.

Touching wire and ground: If a bird touches both a power line and something grounded (like a utility pole, guy wire, or transformer), it creates the same dangerous situation humans face.

Wire-to-wire contact: Birds can be electrocuted if they bridge the gap between a power line and a grounded piece of equipment, or between two lines with different phases of electricity.

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