Birds like power lines because they like being high up and having an unobstructed view of prey or oncoming danger. Standing on a wire put them at no short term risk unless they have one foot on two lines with different currents. Then they catch fire and cause a fire. Longer term it does throw off their quantum time and cause mitochondrial inefficiency but it is not perceptible to the bird.......but if done over and over it will shorten its life. While on the wire, if the bird touches anything "grounded," meaning anything with no voltage, such as the earth's surface or the wooden pole (which is also grounded), the current would instantly flow through the bird's body to reach the ground, and the bird would be immediately electrocuted. When birds are standing on a single phase power line with both feet on the wire, they actually do get electric shock. However, it is in the nano-voltage range so they don't perceive any sensation but it does alter their SCN. Even though they do not complete a path to ground, they are in fact in parallel circuit with the power line. Since the power line has not 0 ohm of resistance, even between the bird's legs, some electric current is deviated into the bird and it gets fried. That is Ohm's law that is found in classic physics! To experimentally show it, you could replace the part of wire between the bird's legs with a Gigaohm resistor, and then observe what happens to the bird. It gets electrocuted. If it touches another phase wire it also gets fried. The power lines on poles are not insulated wires, i.e., they do not have insulation wrapped around them. They can’t! They would overheat under high load (current carrying) conditions. Overhead power lines are generally made of stranded aluminum conductors with steel reinforcing core wires (ACSR), although some older conductors are still copper. The insulation comes into play at the ceramic insulators that hold the wires away from the wooden or metal poles/towers. As long as the insulators are intact and relatively clean, the voltage potential is maintained and there is no path to ground. Birds are safe on electified conductors as long as they are only in contact with a single phase. Often, the larger birds, such as hawks and owls, will sit on pole tops. When they take off, their wing tips may brush across two phases, it is deadly for them and can cause forest fires. Since electricity always follow all the given paths, but how much current flows through those paths depends of their resistance of the circuit. Most of the current in a single phase high voltage wire stays in the wire and does not pass into the bird.
Topic: Birds on electric wires (Read 9109 times)
