When asking a similar question I have received two answers:
- a lightning line does exist topmost on the local distribution
poles that (i assume) were grounded from the poles
- no, said a lineman-cowboy (they have rodeo competitions)
in the grids he's worked on (rural) they do not have lightning
lines on top.
(two different explanations yet I was also told by an EE i think
it was, that the lightning line was, locally, topmost wire, though
now am thoroughly confused.)