Yes - here in the States the balls are orange, and are mandated by FAA regulations where lines cross open expanses that helicopters might want to cross. Interestingly, birds won't go near high tension lines (although they sometimes build nests on 69KV poles). The "induction" apparently bothers them as much as it bothers us. Lower voltages don't seem to affect birds much.
Interesting to use windmills for piecework production. They are poorly suited for public grids because they are too intermittent. Some think any windy spot is suitable, but the requirements are daunting. The site must have reasonably predictable winds mostly around the rated speed (presently about 12 m/s or around 25 mph). Since the power output changes with the cube of the wind speed, dropping the wind speed from 12 m/s to 10 m/s means a 40% drop in output - a real budget breaker when you are contracted to deliver so many MW. Here in the States many wind farms too often operate at a loss because of failure-to-deliver penalties, and proposed FERC rules relating to power hygiene (such as phase regulation... wind farms have been bad neighbors on the grids so far) could make that worse. But for producing hydrogen they could theoretically be made to pay off.
Mike