What he says is this: 5m from the satellite dish there's a _support_ for the OH power line, and the support is grounded to the lightning conductor. Now he asks whether it is advisable to ground the satellite dish support to the lightning conductor as well. Nothing to do with the OH wires themselves.
Anyway, 90V, 9mA is way too much for something like that. You could try to find the source by unplugging each part of the system until you've found the faulty part.
