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Electric fence and fence charger troubleshooting

Over the life of an electric fence and its fence charger, problems can and will occur. This information is designed to help you track down and reduce or repair your fence problems.

Suggested troubleshooting equipment includes:

 Choosing a voltmeter or 'analyzer'

Attempting to troubleshoot bad grounds and fence shorts with a small, single or multiple-neon-light tester is almost impossible if the fence is a low-impedance fence. We recommend you buy a fence voltmeter.

The name voltmeter is misleading; these instruments contain special circuitry that withstands the very high voltages and yet is able to respond to these voltages, which are on for only a few millionths of a second. A standard AC or DC voltmeter cannot do this.

A standard electrician's voltmeter or electronic multimeter will not work with electric fences. The very short duration pulses will not register on instruments like these and will likely damage them! We have had many calls from people who have ruined good electronic multimeters and electricians' voltmeters by attempting to use them for fence readings!

Voltmeter-type instruments designed to read the direct current (DC-output) pulses from CSA-approved fence chargers will not work with alternating current (AC-output), or 'weed chopper' fence chargers! AC-output fence chargers will usually damage these devices.

Most analyzers can be used on both high and low-impedance fence systems. However, always keep in mind that the effective voltage drops to a much greater degree at poor splices and underpasses on the older, high-impedance systems than it does on low-impedance fences.

Three types of fence voltmeter/analyzer instruments

Try to purchase an instrument that has the test probe attached to it; these are much easier to use! Hallman's Shock Analyzer is an example of this type.

 Troubleshooting with an analyzer

  1. Assuming there is little or no shock on the fence, find out if your fence charger is producing adequate shock. To do this, disconnect the fence at the output terminal of the charger. Check between the charger's "fence" and "ground" terminals using the analyzer. The probe goes to the fence terminal and the black clip lead to the ground terminal. You should read at least 2,000 volts. If not, the charger is probably defective. If the charger is working, him reconnect the fence wire.

    Note: when a low-impedance fence charger is connected to a fence, the apparent output voltage tends to rise!

  2. Go to where the feed wire from the charger connects to the fence. Push the portable ground rod into the soil, attach the black lead, and then test the fence voltage between the "hot" fence wire and the rod.

    If there is a grounded fence wire, check the voltage between the "hot" wire and this wire. If the voltage is higher here than at the portable ground rod, then you have a poor ground rod system. If the voltage is low at either ground, then go to step 3.
  3. If the end of your fence has been brought back to the beginning (fenced in a circle), then disconnect any wiring that connects the two. This could be as simple as perhaps opening an electric gate in some installations.

  4. Troubleshooting with an anayzer, step 3
  5. Check the voltage to ground at both the 'beginning' and the 'end' of the fence. If you are using a powerful low-impedance charger and there is a short-circuit somewhere along the fence, the 'end' should indicate zero volts and the 'beginning' somewhat higher.

    Leave the 'beginning' to 'end' jumper(s) still disconnected; start walking along the fence and take periodic readings to ground. The closer you get to the short-circuit, the lower the fence voltage will be. Beyond the short, the voltage will remain zero.

    At the first zero reading you will have to start using eyes and ears to locate the failure. See the picture below. The voltages shown are only to illustrate the principles involved.

  6. Troubleshooting with an analyzer: step 4
  7. If this method does not work, move along the fence to where the 'hot' fence wire(s) are spliced together. After disconnecting a splice, check the voltage between the fence section still connected to the charger and the portable ground rod.

    If the voltage is now acceptable this means that there is a short between the section of fence beyond the disconnected splice and ground. In this case, reconnect the wire and move farther down the fence, away from the charger.


  8. At another point where the 'hot' wires may once again be disconnected, do so, and repeat the tests in step 5. If, at this next section, suitable voltage is now present, then the fault lies even farther out. See the picture above. However, if the voltage reading remains low, then the fault is in this section, between the two breaks you made in the 'hot-wires. by this process of elimination the defective section can be found.

 Other uses for analyzers

Grounds

Analyzers are excellent for indicating poor grounds on multiple strand fences that have at least one uninsulated ground wire.

For example, if you find a higher voltage between a 'hot' fence wire and a grounded fence strand than to a portable ground rod, then the charger's ground rod is not effective. If the voltage reads higher to the portable ground rod, then there is at least one poor connection, such as a loose jumper, somewhere along the fence ground wire.

Other uses for analyzers: grounds 1

There is a rare grounding condition that mystifies many farmers, although it doesn't require an analyzer to solve. It usually occurs when using low-impedance, very-high output fence chargers, such as Hallman's Trident.

If the ground rod system is inadequate and a heavy short takes place on the fence, probably near the end where the fence charger feeds it, then a shock will be experienced when touching the ground rod and the ground! The image below shows this phenomenon. The solution is to locate and remove the fence short and then install a proper ground.

Other uses for analyzers: grounds 2

The principle involved here is one of a short-circuit on the fence wire creating a closed electrical circuit, with two main resistances: one at the short and the other at the poor ground rod connection. The larger a resistance is, the more shock there is across it. Because the ground rod to earth connection is poor (has considerable resistance), some of the high-voltage shock appears accross there.

Livestock water bowls

Voltage as low as a few hundredths of a volt can prevent cattle from drinking from their water bowls. If your livestock are not drinking, check to see if you get any voltage reading between your charger's 'ground' terminal and the hydro ground, such as a metal switch box. If you do, your charger's ground system is not functioning well.

Farmers who use their cattle stanchions as a ground rod, or drive in their ground rods within the foundations of the barn, often experience this effect. Animal stanchions often work quite well for a few years as a ground, and then suddenly create odd problems. This is usually caused by the soil receding under the concrete floor and drying out. For more information, see Grounding tips.

Splices and joints

On older fences especially, splices and joints can become real 'shock-stoppers.' There are two ways to test a splice.

Underpasses

'Leaky' underpasses can cause problems. An underpass is where a well-insulated wire is buried between two gate posts (see below).

Other uses for analyzers: underpasses

To test, at the gate post nearest the charger, disconnect the underpass wire from the fence wire. Measure and note the voltage (see above) and then reconnect the wire.

Next, disconnect the underpass and fence wire at the other post and measure the voltage at the disconnected end of the underpass wire (see above). If the voltage here is more than 500 volts lower than it was at the other gate post, there is considerable leakage into the ground. The only solution is to bury a new wire, following the installation instructions in Fence layout and installation.