Why don’t birds sitting on power lines get electrocuted?
The damaging effects of electrocution are due to an electric current flowing through your body. Electricity won’t flow into a bird sitting on a high voltage wire because there is nowhere for the electricity to go after the bird, except into the air. So the bird is safe if it is standing on one wire. If it landed with a foot on two different wires, then …zap! Electricity would travel from one wire, through the bird and into the other wire. Similarly, if the bird touched an object in contact with the ground, the electricity could flow from the wire through the bird on its way to the ground. In this case, the bird has “earthed” the wire. High voltage wires are well spaced and well away from the ground, so birds, which are usually small, perch quite safely on one wire.