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How To Find A Break In An Underground Dog Fence (3 Methods To Try)

Key Takeaways

  • Breaks in the invisible dog fence wire are the most common issue you’ll encounter when using an invisible fence.
  • Fortunately, there are a few methods you can use to find these breaks and get your system back up and running as soon as possible.

An underground dog fence is one of the most reliable ways to keep a dog confined to a specific area, and is considered to be fairly humane to boot. This is especially true if you purchase a model that only uses citronella spray or similar, which is my preferred kind of correction if I can get it. Invisible fence systems are endorsed by animal behaviorists, veterinarians, veterinary schools, the ASPCA, and HSUS[1].

But even the best invisible dog fence is not immune to damage and faults. One of the most common issues that arise with invisible fence systems is the wire break, which can happen due to a number of causes. Perhaps the most clear sign that this issue is starting to take shape is when your dog is suddenly able to run through the invisible fence at certain points. Fortunately, there are about just as many ways to find and fix them too. You can take some extra wire and shorten the circuit to narrow down the broken segment, or use a wire break locator to pinpoint it. Or, you can do what I do when I don’t have either on hand (or when I just feel like a challenge) and use an AM radio to find the break in the dog fence wire by listening to the static.

Three Different Methods Of Finding A Break

If you think there may be a break in your underground dog fence, there are three effective methods of finding the defect that includes:

  • Short loop test method with extra wire
  • Wire break locator
  • AM radio

Making use of a wire locator to find the invisible fence break is perhaps the most straightforward method. However, you also have to understand how the short circuit method works in order to employ the locator correctly and find the break in the underground dog fence wire.

Before Looking For a Wire Break

First, do a physical check by walking the area of the electric dog fence wire. Look for signs of damage, such as disturbed ground or trees that have been uprooted. Any sign of significant disturbance is likely where there will be wire breaks. This should be simpler if you did a DIY installation, or if you personally supervised the installation of your invisible fence wire, as you would know where the buried wire is laid and would be able to unearth it more easily.

Then, take your extra wire and test whether the transmitter is working correctly. A short length of test wire will do for this, and some invisible fence kits even come with a short wire meant exactly for this. However, it’s a little quicker if you just use the whole length of your extra wire to test the transmitter.

Disconnect the boundary wire connection from the transmitter and connect your test wire. If the transmitter is working correctly, it should light up upon connecting the wire to the positive and negative terminals. If not, you may not have a break in your dog fence wire system at all, but instead may be dealing with a broken transmitter.

If the transmitter is working correctly, test the receiver collars. Hold them close to the test wire and check if they beep and/or emit static. If they don’t do either, it may just be that your collars aren’t working. Try to replace their batteries or test with other collars.

Short Loop Test With An Extra Wire

How to Find a Break in Underground Dog Fence

After verifying that the transmitter and collars indeed work, dig up the buried wire at the halfway point and then cut it in half. Take the rest of your extra wire and plug it into one of the transmitter terminals. Then, plug in one end of the boundary wire into the other transmitter terminal. This can be difficult considering you probably have twisted wires leading from the boundary line to the transmitter as per usual manufacturer specification, so you may want to untwist them for the duration of this test.

Afterwards, connect the other end of your extra wire with the segment of the boundary wire that you just plugged into the transmitter. If that segment is unbroken, the transmitter should light up and/or beep. Do the same for the other half. If neither of them make the transmitter light up, you’re dealing with more than one break.

Once you’ve found the half that has a break, you’ll have to dig that up at its halfway point as well and then test the segment that’s connected to the transmitter. Repeat this until you’ve narrowed down the segment with the break in it. Since this test can obviously get very laborious, you may want to limit it to two to three cuts to minimize the number of splices you have to do when you’re putting all the disconnected wires back together. You can also try to tug at both ends when you dig the segment up at the halfway point to check if it’s loose on either side. This can help you find the break more quickly.

When you’ve narrowed it down to perhaps a quarter segment of the boundary wire, unearth the erring segment so you can move on to examining uncovered ground wires for visible physical damage. Repair or replace this broken segment and use your extra wire again for testing wire continuity. Repeat this each time you reconnect one of the segments you cut off to find the break.

Using A Wire Break Locator

Wire locator.

This is by far the easiest way to find a break, with wire break locators specifically made for the invisible fence model being the simplest to operate. These often come with their own easy-to-understand manuals, but if you don’t have one on hand, you can use a multimeter to run a small current through the circuit.

Wire break locators specifically made for invisible electric dog fences usually connect to the twisted wire that plugs into the transmitter box. The locator is then held all along the whole perimeter of the boundary wire, close to the ground in order to properly receive a definite signal from the wire. Once it moves over the wire break, it will beep, letting you know at which point to start digging up the dog fence wire system and make repairs.

Using An AM Radio

AM radio.

If you can’t get your hands on a wire break locator compatible with your system, you can potentially make things easier for you by using an AM radio. As you may know, invisible fence wires emit a radio signal that the collars then pick up. You can pick up these same signals with an AM radio tuned between 500 and 700 kilohertz.

With the radio in your hands, walk over the boundary wire perimeter and wave the radio left and right. Make sure the radio isn’t tuned to any specific show. It should just put out static. Once you’re standing over the break, the static should noticeably weaken in volume or even cut out. This should tell you the general area where the breakpoint probably is.

Fixing An Underground Dog Fence

  • Dig up the location where you find the break
  • Strip the wire covering away from both ends of the broken wire
  • Remove all the dirt and clean the wire
  • Twist the ends together if frayed
  • Connect the wires by using an underground wire splicing kit


1. How do you find a broken underground dog fence?

You can find a break in an underground dog fence by understanding the order of the steps to repair the break. You may use one of these methods:

  • A short looping method with an extra wire
  • A wire locator with a short looping method
  • An AM radio and lawnmower spark plug

2. How do you find a break in a pet-safe fence?

You can find where the break is in a PetSafe fence by using a wire locator with the short looping method. A wire locator is effective for locating wiring in a pet-safe fence, electrical wiring, metal pipes, or metal wiring. To find the precise location of the break, move the wire locator over the area. When the transmitter’s tone changes, turn down the volume. The tone will disappear when you locate wire breaks. Using a wire locator to repair the break yourself is less expensive than hiring a contractor to complete the work.

3. How do you fix a broken invisible fence wire?

Using one of the three methods for locating a break in an invisible wire fence, dig up the area. Strip the wire coating away from both ends of the broken wire. Remove any dirt and thoroughly clean the wire. Twist both ends of the wire into a wire shape. Connect the wires together with a wire splicing kit. By following the steps for each method you should be able to repair a break in your underground dog fence.

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