While the length is an issue isn’t the expansion problem resolved by it being wrapped in a helical pattern? You basically have a spring at that point which can

While the length is an issue isn’t the expansion problem resolved by it being wrapped in a helical pattern? You basically have a spring at that point which can contract and expand with less stress than a pretensioned straight wire fixed at two points since it can slide across and rotate around the power line. For repairs I’m guessing there will be no or very limited splicing you can have connectors at each pole and simply run a new fiber if you have a fiber break mid line the main reason for splicing fibers today in below ground installations is that pulling them out requires you to dig up a whole bunch of dirt if it’s just plug and let the robot rewrap the fiber along the power line I think it’s cheaper to do just that.