Have you ever seen those big yellow, orange, white or red balls hanging from power lines? Well, those balls are visibility markers. They weigh about 17 pounds each, and you will often find them near mountain passes, in deep valley areas, near major freeway crossings and around airports.

Visibility markers are placed on power lines to make the conductor crossings visible to aircraft pilots. The conductors and skyline wires become almost invisible against the terrain when flying. Moreover, helicopters and small planes often fly low in mountain passes or over freeways while approaching airports.

Spherical visibility markers, specifically in “aviation orange, white or yellow,” are required by the Federal Aviation Administration, like those near airports. Southern California Edison has identified additional power lines within its service area that are particularly hard for pilots to see and proactively installed visibility markers as enhanced safety measures.

So, next time you’re driving past power lines with marker balls, you can proudly share that they’re used for the safety of flying aircraft and are critical to protecting the electrical infrastructure.