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EFFECTIVENESS There have been electric fences used all over the world for the last 75 to 100 years. They have been used effectively 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. (Even Elephants)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 "hot wire" ... 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 are 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 or less 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 for most security situations. Of course, higher is better, but there is a diminishing security return for an electric fence much over 2 meters high. 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. This type of connection allows a "fence monitor" to keep track of the condition of the total fenced perimeter. It is best to make the fence "look" as lethal as possible. 90% of the effectiveness is in the perception of the intruder/trespasser. Many sites selling electric fence Components have a gallery of pictures. 3. The biggest design difference is; by loop connections and 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 throughout the complete fence. 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. A more sophisticated monitor will also provide an alarm when the voltage drops due to weeds, grass, or other undergrowth. 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 without a helicopter or pole vault. However, remember that there is no device that is 100% fool proof. Watching any James Bond movie will show you that. The high voltage security fence will keep out 99.99% of the intruders, but there is always a way to beat the device. In extreme high security installations, the security is done in layers. If the first layer is penetrated, then hopefully, the 2nd, or 3rd, or the 4th layer or device will catch them. We will say, that a high voltage electric fence that is properly designed and installed is the most cost effective high security method available today. Truly "State-of-the-Art"
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