Yes sorry plastic water pipe, so we’ll have to go galvanised conduit then.
Thanks I’m all to familiar with waterproofing joins and connectors, I do it with my antenna connections all the time. I have my own little method I worked out over time, a combo of rubber tape and insulation tape to make it both water and UV proof.
Not really. As @Phil.g00 explained you need a conductor and galvanised wire will be as good enough.
Anyway it will be a lot easier and cheaper to run next to your cable to check if it works…
I would not trust just another wire on top. You want to prevent any and all energy transfer into the electrical wire, kind of a faraday cage if you will.
Groetnis
That cable has design insulation of, say, 2kV, and as the lightning has to break into the cable and break out of it again, we can effectively double that value. Anyway, suffice it to say it represents a massively higher impedance than continuous bloudraad.
The charge isn’t from everywhere. It is bottlenecked at the fence gate and heads up the cable to its destination.
Sure, a surrounding metal conduit will provide the same electrical outcome. But it will not provide a better one at (a hundred times?), the cost.
I’ll debate that bloudraad will last longer in the ground as well
You only need a wire from the charge point to the discharge point to short out the impedance of the cable’s insulation.
Swallows sit on live telephone wires without current going up one leg and down the other and electrocuting themselves.
That little stretch of wire between their feet shorts them out and gives them Faraday cage protection. That is what needs to be replicated here.
That is all a Faraday cage does; it exploits how a low impedance carries all the current when it is in parallel with a far higher impedance.
That far higher impedance being… you? 
from cigarette packed calculator to bloudraad… makes sense 