I notice a new high voltage transmission line being built a few miles away here in the western U.S. has all of the newly installed carrier lines equipped with a "spacer" between each. This appears to be a semi'flexible fiber glass bar about 12 iches or so long and maybe 1 inch in diameter. The installation of the lines involves the use of a helicopter to actually place the lines on the towers some 75 to 100 feet above the ground level. I had the opportunity to talk to one of the highly skilled pilots (the operations is something to behold) the purpose of the "spacers" and he said it was to keep the lines from performing "line slap" in high winds. It's also called "line gallop" and is more pervasive if ice has accumulated on the lines...
The lines slap together momentarily causing a breaker switch at a line station to quickly open and then close once it determines there's not an actual short for which the breaker is the main protection...