Electronic Alarm System
Product
Let's build a legal security barrier that shocks anybody that touches it, and will trigger an alarm if cut, climbed, shorted, torn down or tampered with. As a bonus, it will also notify us if the voltage falls below a certain threshold.
An Electronic Alarm System, or array, can be freestanding, placed atop a wall, or attached to an existing fence. Since most electric security arrays are added to the inside of a chain link fence, that's the example we're going to use, but the principles are the same.
We see an array attached to the inside of an existing fence. The wires of the array start a few inches above ground level, and there’s a wire every 4 to 6 inches, to a height of 8 or 10 feet. We run the array all the way up because existing fence are easily cut with a $10 bolt cutter.
Alternate wires of the electronic system are grounded to ensure that anything coming over or through the array receives a shock. If the wires remain in contact with each other for more than a few seconds, it will also trigger the alarm. If a hot wire is cut, the alarm sounds.
This also negates throwing a mattress or other insulator over the array because the fence will short out, which triggers the alarm.
A optional solid cement footer, or some rows of heavy debris along the base of the fence can be used to prevent digging under the fence.
Another way to prevent digging is shown in Figure 2. We run the array horizontally for three feet across the ground to prevent predators and other thieves from digging their way in.
In our experience, we have never had a trespasser attempt to dig under an array. They have always tried to come over it or through it. After the first shock, they leave and don’t return.
Another special case is keeping snakes out of utility installations. Our systems are used for this extensively in Texas.?Contact us?for snake-proofing and other specialized designs.
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