Surely you've seen them: bright colored balls strung on overhead electrical power lines.
These are called "aerial visibility marker balls" or "aerial marker balls" and they usually come in "International Danger Orange" color (yes, that's the official name of the color). These marker balls are used to make power lines and wires visible to low flying helicopters and aircrafts.
But have you ever wondered how these balls get put up there in the first place?
If the power lines are being put up, the balls are installed on the wires as the lines are being erected but for existing power lines, a helicopter and a brave operator are called for.
From Core77:
But in the case of existing wires, aerial marker balls are installed, ironically, by helicopter. A guy sits on the side of a platform over the skids and hangs onto the ball. Arriving at the right spot on the power line—which is pre-marked on a separate, earlier trip with spraypaint—he then has to open the ball like Pac-Man, muscle it over the wire and bolt it shut. He then wraps some attaching wires on the sides around the power line itself.
Sometimes the ball is so large and heavy that it has to go up in two trips. Because it's not like it's mounted in a bomb rack; the installer has to hang onto it. Despite its name, this SpanLite model made by P&R Tech can be up to 51 pounds and due to installation requirements, it's carried up and hooked up one half at a time, with the helicopter touching down in between.