Eli5: How are birds able to sit on electric fences and wires and not get electrocuted?


Eli5: How are birds able to sit on electric fences and wires and not get electrocuted?

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Electricity wants to go to ground or something with high electrical potential. So if you’re not touching the ground (or another wire), it would prefer to stay in the wire. Compared to the wire, a bird would be less conductive, so it stays on its current path. If the bird touched another wire, that would be potentially giving the current in the first wire another path.

Electricity follows the path of least resistance to the ground.
a bird is more resisty than the rest of the wire, even before you add the insulation to make it more resisty.
When you touch the wire, your feet are touching the ground.
Rather than going all the rest of the way, with all the resistance that needs, your body is shorter path to the ground, and hence the path of least resistance is you. So you become the conductor and get electrocuted.

Think of the wire as a pipe with water flowing through it, except when something touches the pipe, they connect to it. A bird on a wire is like hooking a glass soda bottle up to the side of a pressurized pipe. Sure a tiny bit of water will probably flow in the bottle, but it’ll quickly reach the point there is too much pressure in the bottle to take any more in. The bottle is a dead end for any water flowing into it.

What if a bird somehow has one leg on a wire and one leg on the ground. Then it’s no longer a dead end. Electricity can flow from the leg touching the wire to the leg touching the ground like a pipe. Since the ground can take lots and lots of electrical charge, it’s like a very big balloon that can take all the water the pipe has to give. This flowing of electricity through one leg and out the other would be deadly for the bird because not only would it paralyze muscles but it’ll heat it up until it probably catches fire.

Electricians often use the same principle when working on potentially electrified wires by touching them with only one hand at a time. So long as it’s one hand their body is like a bottle. Touching with two hands and they can potentially become like a pipe.

They’re not touching the ground.

You only get shocked from an electric wire because your body is offering the electricity a shortcut to the ground vs having to keep being forced along the wire. A bird’s body doesn’t provide such a shortcut, so there’s no reason (or available path) for current to flow through them.