How To Find Break In Invisible Fence

Think you might have a break in your invisible fence wire? We show you three ways to find it. One using the short looping method with an extra wire, one using a wire locator with the short looping method, and the final using an AM radio.

The order is important. Even if you buy a wire locator you need to understand the short circuit method to find the break. A wire locator just finds the wire and only works with a complete circuit loop.

Lastly we’ll show you how to fix it and how to avoid the problem in the future.

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How To Find Break In Invisible Fence Using An Extra Piece of Wire and the Short Looping Method

  1. Stage 1 – Do a physical check. Walk the buried wire looking for areas where it’s damaged, pulled out of the ground, tree roots uprooted from a down tree, etc.
  2. Stage 2 – Short the loop at the transmitter to test wire from the transmitter to the property boundary. Follow the wires from the transmitter to where they go underground in opposite directions. Cut both ends there and short them together so the signal no longer travels underground. This will short the loop and send the signal back to the transmitter. If the transmitter stops beeping then there’s no problem from the transmitter to the boundary and the problem is underground.
  3. Stage 3 – Test underground sections using a wire bridge. Next you’ll test the underground areas by short it with a wire bridge. Take an extra length of wire and run it over a section of underground wire. Carefully dig out the underground wire at both ends of the run. Cut the underground wire at both ends and connect the above ground wire to make a bypass. If the transmitter stops beeping you found the break. Use a new, thicker wire as described below to prevent future breaks and install that.
  4. Stage 4 – Transmitter issues. The last issue you can have is the transmitter is malfunctioning. Maybe lightning or an energy surge has damaged it. The only solution here is to get a new transmitter.
  5. Preventing future breaks – Use a thicker wire (1 mm, 7 strand copper) with an high density polyethylene (HDPE) coating that has a 20 year UV rating. PVC coated wire will break down in the sun.

How to Find a Break in an Invisible Fence Using a Wire Locator

The most common way to find a break is to use an underground locator. After some testing of different models we recommend the Kolsol Underground Wire Locator.

Watch the video below for a demonstration of how to use it. This locator can detect wires up to 80 cm away from the sensing unit. It looks deep.

Here’s how to use it.

  1. Turn off your underground wire transmitter.
  2. Connect the two clips on the Kolsol transmitter to underground wire  – Use pne clip for each different in and out wires to the underground transmitter.
  3. Turn on the Kolsol transmitter.
  4. Turn on the Kolsol detector and adjust the volume. The detector makes a noise when the sensor is within 80 cm of the underground wire.
  5. Walk the underground wire path.
  6. Short Looping Method to find the break – The Kolsol transmitter clips must connect to an unbroken length of wire to form a complete circuit. that if there’s a break then the Kolsol detector won’t be able to see the wire. You’ll need to use the short looping method shown in the next section to find the broken wire. You’ll move the Kolsol transmitter and clips to different sections of the underground wire to find the break.


Kolsol Underground Wire Locator Cable Tester F02 With Earphone for Locate Wires and Control Wires Cables Pet Fence Wires
  • 📏【Time and Money Saver】Helpful-Locating & tracking buried and hidden wires.No more calls,no more cost, find and fix it by yourself.
  • 📏【How to Use】Easily Locate Pet Fence Wires, Metal Wires, Metal Pipes, Electrical Wires, ect ( only for single-strand wire, or double-strand wire in parallel, not for multistrand wire!!!)
  • 📏【Where You Can Locate】Locate-Determining Which Receptacles are on specific circuits,track-Pinpointing Drill Sites before drilling.
  • 📏【Range of Parameters】Wire tracer range-Up to 2-3 feet deep and 1000 feet in length.
  • 📏【Earphone & Tips】Get a free Earphone with package. Tips: Do not use on live circuits to avoid damaging the Tester!This device is mainly to locate non-energized Cable, or low-voltage situation less than 24V .Only for Wires & Cables,Not for Sprinkler Valves!!

How To Find Break In Invisible Fence Using An AM Radio

Don’t have a wire locator? Save the $70 and make your own DIY locator using an AM radio. What you are doing here is making a DIY wire locator using a lawnmower as a transmitter, a wire to connect the transmitter to the underground cable, and the AM radio to find where the wire is located.

This method will allow you to check up to 2000′ of underground wire till you find a break. If you have a longer segment than that just use the method from both ends for 4000′ of total checked wire. If your section is longer than that see the short circuit method above.

Just follow these steps.

  1. Equipment needed
    1. 4 stroke lawnmower – This will act as a transmitter providing a small charge causing a slight static output from the underground wire.
    2. 20 – 30 feet of test wire (extra wire from your underground kit will work). You’ll connect this from the lawnmower’s spark plug cable to the underground wire.
    3. AM Radio with antennae – This will be used just like the wire locator above.
  2. Disconnect your underground system’s main transmitter from the main underground wire.
  3. Loop one end of the test wire a few times around the spark plug cable of the lawnmower.
  4. Connect the other end of the test wire to one of the ends of your underground wire.
    1. Note – This method doesn’t require a complete circuit. It’s ideal for finding a break.
  5. Turn on the lawnmower. That will provide a low frequency static output to the underground wire.
  6. Turn on AM radio and tune to 530 kHz. This is low enough to hear the static coming from the underground wire without picking up other radio shows. If there’s a conflict keep trying other stations till you find an empty station with no radio show that also picks up the static noise coming from the wire.
  7. Wave the AM radio over the wire. Static will increase as you get closer to the wire, stop right over the wire, increase again then die off as you move away from the wire.
  8. Learn how the static works by testing it over an above-ground piece of the wire.
  9. Walk the wire till you find the end (static stops). That’s where the break is.

How Do You Fix A Broken Invisible Fence Wire?