There have been electric fences for the last 75 to 100 years. They have been used effectively all over the world to contain all types of domestic livestock, from cattle and horses to wild deer and antelope. They have also been effective in protecting crops from nuisance animal pests of all types. Most of us that have lived in the country/provinces have had experience with electric fences of one type or another. You jump over, or very carefully crawl under the hot wire to cross the fence. This was/is not much of a security device even though we wouldn’t touch the hot wire for the most entrancing enticement.

Why?
The fence as described is design for effective cost management and primarily designed to keep the livestock safely contained. Even a half-ton bull will stop short of the “hotwire”. So now we design a fence primarily to keep out humans that climb, that think, that cut wires, that crawl under, that jump over, that short out the “hot wire” and generally is more difficult to deal with. We know that the human trespasser is deathly afraid of touching the “hot wire” and getting a nasty shock. So we lay out the fence so the human cannot go over, under, or through the fence without getting badly shocked.

High Voltage electric fences have only commonly been used for security applications for the last 4 to 5 years. There are several main differences in design that make a standard electric fence viable for human security.

1. The first difference is the spacing of the strands. 6 inches apart is considered the most effective spacing. The bottom strand should be even closer to the wall or footer, as close as 3 inches. The reasons for this are self-explaining. Usually 2 meters high or 12 to 14 strands in sufficient. Higher is better, but there is a diminishing return for much over 2 meters.

2. The bottom strand is almost always a “hot” strand, and then alternating with grounded (good solid earth grounds) strands. In a security fence you do not parallel the hot strands, but interconnected at the ends of the fence so that, electrically, there is only one strand that is doubled back on itself, and redoubled again if necessary. It is best to make the fence “look” as lethal as possible. 90% of the effectiveness is in the perception of the intruder/trespasser.

3. The biggest design difference is; by maintaining a single strand (electrically) you feed the high voltage into one end and monitor the high voltage at the far end of the strand. There by ensuring the “High Voltage” is present all the time. If the high voltage is cut or shorted, then the High Voltage Monitor will close a set of contacts to activate an alarm of choice. So if the intruder cannot go over, or go under, or go through the fence without being shocked, and the intruder cannot short out the fence or cut the wires without setting off the alarm. The fence is virtually almost impossible to penetrate.