Next time I'm over there I'll take some close ups. It's actually both a diverter and choke. I should put more diverters further out on the fenceline.
http://www.gallagherusa.com/electric-fencing/permanent.component.aspx?mktprodid=1360
That rig connects to the fenceline, then I have leadout wire from it to the charger, there is also a knife cut out switch. Diverters allow the electricity to arc and ground. The choke is supposed to form an electromagnetic field when lightning goes around the coil and reverses the direction. I used to use 3/4" HDPE pipe, now I PowerFlex posts.
My mom and I used to build some fences back when I was in Jr. High/High School in the 90's. We took over as a Gallagher Dealer when the guy who built our first high tensile fence retired. I didn't do much of it while I was in college and living out of state before returning home, but I've learned everything I could the last few years and make a much better fence now. Now I have people asking me to build for them and I'm going to try doing some part time contracting again. I really would like to get a post driver with a rock spike, I'm eyeballing this Vector brand. The Shaver I have is good most of the time, but it's terrible when I hit rocks and clay. It's also challenging sometimes, at least in my soil, to get posts in at the exact angle I want with the Shaver. Also, the shaver doesn't sink an 8' post quite deep enough, the driver bottoms out.
Those stone walls you see, not sure how old they are, this was one of the original 13 colonies, but was Massachusets then. I'm farming some fields that were farmed before the Revolution. Gorham was founded in 1736.