An electric fence can cause problems when it becomes broken, or looses its completed circuit. For both underground security fences as well as the above ground ones, a fence break locator is the way to go to efficiently find where the source of the problem is. How a locator works is that electricity gives off 2 things, electricity and the byproduct of this is a radio wave.
Radio Waves and Direct Current
It is interesting to know that all electric fence installations carry a radio signal in them from the dispersal of their electric current. It is this signal that a locator would use to trace the fence line detecting breaks in the system. As with a dog collar on an invisible, under the ground fencing system, the dog collar responds to the radio wave of the fence turning on the shocking device. The shock does not come from the fence itself, it comes from the collar which is turned on by the fences radio signal.
Above ground electric fence uses electrical shock as a deterrent once it has been touched or makes contact with the skin. The owner can regulate the strength of this current at the relay box. This is so a fence can be turned up for large livestock and turned down for smaller animals to prevent damaging them badly with electrocution.
Radio Wave Detectors
The most common and popularly effective method of finding breaks in both under ground and above ground electric fence systems is through a radio broadcast. As you walk the perimeter of your fence line, this radio will give off a humming or light static noise as you go along the length of the line. When the line is broken or interfered by a short in the line or an obstruction, the radio signal will lag, change pitch or even go dead completely. This is a signal that there is not an electric current at this spot as there is not a radio signal coming from your wires at this location.
Broken Circuit Detectors
Another method which is not suggested as it is laborious, and can take quite some time to achieve, is using a circuit detector or voltage reader. This is a bit more involved, as you need to ground the wire on your device which can be a chore on an invisible fence. A buried or invisible fence is harder to work with, as you have to first find fence itself, and people have said it is just easier at that point to replace the entire thing.
Once you have the ground wire secured to your electric fence, take the probe end to check for a break in the circuit by reading your voltage meter. The device has a voltage reader on it and it will not register if there is not a current touching the probe end of your device. All this is doing is using the current in your fence to power the meter, and its regulator determines the total output of that current. When the meter reads zero, and your on a line, simply travel back until you get a reading again. Once you have determined the location where the current vanishes, you have found the break.