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What are those orange balls on some power lines? – Maggie, age 8, West Chester, Pennsylvania

What are those orange balls on some power lines? – Maggie, age 8, West Chester, Pennsylvania

Have you ever looked up while driving on a highway and spotted those big orange balls hanging on power lines? They look a bit like giant toy beads strung along the electric wires.

What in the world are those overgrown basketballs doing up there?

I’m a professor who teaches about and researches power systems, the big networks that move electricity from power plants to our homes, schools and businesses.

Those big orange balls don’t help with electricity flow or improve the efficiency of the power lines, but they do have a very important job. Officially called aviation marker balls or spherical markers, they’re there to help pilots see power lines so airplanes and helicopters don’t crash into them. They’re like bright warning signs in the sky, protecting pilots, passengers and people on the ground below.

Big round warning signs in the sky

Power lines can be very hard to see from an airplane or helicopter, especially when pilots are flying low. Thin metal wires can visually blend into the background of........

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