what's the name of balls on power electric lines?

Answer 1

The large balls are known as aircraft warning markers. They are used to make the power lines more visible to pilots. When you or I look up at the wires, they are seen against the blue (or gray) sky. When pilots look down, the wires tend to blend in with the ground.

The balls generally range is size from 30" to 52" in diameter.

You'll often see the markers on wires that are inline with the end of a runway. While there is plenty of clearance for the planes and their glide slope, many locations put up the markers anyway. They will also appear over large river crossings where it is common for pilots to fly along the path of the river.

Any structure that exceeds an overall height of 200 feet (ft) above the surrounding terrain should normally be marked. The FAA may also recommend marking a structure of lesser height located within 20,000 ft of an airport or 5,000 ft of a heliport.

Answer 2

Aircraft warning markers

Answer 3

arc insulators