What are the coloured balls that are attached to power lines for? © Getty Images

What are the coloured balls that are attached to power lines for?

These coloured balls are known as marker balls and they're designed to stand out and act as visual warning signs.

Asked by: Claire Buckley, Ireland

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The coloured balls on overhead electricity cables act as visual warnings for low flying aircraft. They are most often used when cables cross major highways or deep gullies or valleys. To aid visibility, the colours are chosen to provide the greatest possible contrast with the background terrain. Where more than one cable is strung between the pylons, the coloured balls are mounted on the highest.


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