We read all the books and heard all the stories about how notorious goats are at getting out of fences, and into gardens. We were planning to tether the goats, and had a complicated system of portable shelters, tethers and rotations. But come early spring, there was hardly enough grass to warrant a tether, and no garden to break into, so we let the does graze with Pilgrim in the big pasture, and they generally respected the single wire electric fence we had up around the perimeter. So we decided to try a double wire electric fence and see how well the goats respect it, before the garden gets going.
First, we measured the goats. The top strand needs to be high enough to discourage jumping, and the bottom strand needs to be low enough to prevent crawling under, and the two strands need to be close enough to prevent climbing through. I won't give exact measurements, because this spacing would depend on the breed and height of your goats. With a mixed herd, including young kids, a three-strand electric wire fence may be better.
It worked out that we hung the top strand roughly at eye level of the does, with their heads up. This gives them a strong visual barrier, once they are trained to respect an electric fence. And it is high enough (about 3 1/2 feet) to discourage jumping over. The bottom strand was hung at about brisket level. When the does are on their knees, as they are wont to do when reaching under a fence, the bottom strand will contact their shoulders, so it is low enough to prevent crawling under. But being at brisket level, it would contact brisket and belly if trying to crawl through. And for the most unlikely feat of trying to leap through the fence, the top strand would contact with their backs. So two stands should do it...
But the other side of the equation is a good zap in the fence, and animals who are trained to respect that fence. Fortunately for us, I don't think the goats had been introduced to electric fencing. Animals will sense when an electric fence is shorting out, and will learn to ignore a light tingle on the way through to the elusive Other Side of the Fence. So a well maintained fence is as important as the spacing of the strands of wire.
Once the fence was up, we hooked up the fencer, and left the does to work it out, watching them for their reactions. You don't want to lead an animal up to a fence and "zap" them, they will associate the shock with you and not the fence. It was Juniper who first sniffed at the wire. Goats, like horses, are sensitive to electric fencing, and just one shock, once they figure out where it is coming from, should be enough to educate them. For Juniper, who is not the brightest button, and has more enthusiasm for adventure than her mother, it took two shocks. Just to be sure that it was the fence that bit her and not a bee. The first one made her jump and buck around, not sure where it came from. The second one made her jump back and take a double-take at the fence, this time sure. Penelope, wisely learned by observing, and I have never seen her touch the fence.
Another test came when we incorporated the 3 month old kids into the grazing herd. The lower strand was at shoulder height for them, and should keep them in as well. Again, we let them out into the pasture and generally walked over to the fence line, since they still follow me around, and let them sniff the fence out for themselves. They each got a shock, right on the nose, and have never wandered too close to the fence line since.