Pilot wire systems used to be employed more here in the past. Out here in rural Norfolk where a lot of distribution is overhead, if you look around the poles you'll often see an extra bracket, now minus its insulator, where a pilot wire for the street lighting through some tiny hamlet once ran.
There's even a spot a few miles from me where the pilot wire is still in place -- Noticeably thinner than the other four (3P+N) conductors. I'm not even sure if that wire has just been abandoned and the lights changed to photocells or individual timers, or whether it's still actually in use.
