Powerlines?

Question

Why do some powerlines have those big balls on them? My Dad use to tell me it was so airplanes didn't hit them, but I have never seen an airplane fly that low. So, what is the real reason?

Answer 1

he is right but should include helicopters---you most commonly see them when a line is strung across a valley or near airports

they are using them also near where endangered condors live because quite a few have died because they flew into the wires

Answer 2

Your Dad is correct. It is very important if it is near the flight path of planes.

Answer 3

I'm not quite sure what kind of powerlines you are talking about ... I am interning for an electricity distribution company, so if you give more detail maybe i can answer.

Answer 4

The large globes 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.