Aart, I use a Zareba 10 mile, 1/2 joule low impedance charger. I have an 8' copper clad steel grounding rod driven 6' into the ground, and I am using a 7 light fence tester. I've been shocked by it (the first time I used the tester, I didn't ground it first, so when I touched the fence, I grounded it!) and it packs plenty of punch! The charger is hooked up to 200' of Premier1 48" chicken net fence.
Gotta love those unintentional hand tests, don't ya?
