How to Find a Break in an Invisible Dog Fence




Introduction: How to Find a Break in an Invisible Dog Fence

Recently I went into my garage to find the invisible dog fence transmitter beeping. After calling the company I was informed that this alarm meant there was a break in the fence, and that I should have them come out as soon as possible - because my dog would surely figure this out in a few days. And hey, for only $100 an hour, they would be happy to help! Long story short, they tried for an hour then told me the yard was too overgrown (half the yard is wooded) and they would have to come back in the fall when everything died back (2 months away). This made me swear that I would do it myself - but after digging up over 100 feet of wire and driving myself crazy for a few days, I had not found the break. Then I found this strategy on the internet (link) that cost me under $20 and worked like a charm. Hopefully this makes it clear for everyone else and saves you some money and frustration. Good luck!

Step 1: Verify the Break

First thing to do is make sure that you do indeed have a break. There are a few ways to do this. On my unit, two wires run from the transmitter to the perimeter fence. Disconnect these wires from the transmitter and put the ends of a paper clip or small piece of wire into the jacks where the wires had been connected. If the alarm is silenced, the transmitter is working properly and you have a break. Another way to verify that there is a break is to use an ohmmeter and check the resistance on the disconnected wires. If there is no resistance the wires are continuous and there is not a break, meaning you may have a problem with the transmitter itself.

Step 2: Materials

To start, you'll need to round up a handheld AM radio and a RF choke (Radioshack part number 273-102).

Step 3: Connect the Choke

Take the two wires that you disconnected from the transmitter and connect them to the leads of the RF choke. Then insert the leads of the choke into the jacks on the transmitter where the wires were originally connected. As I understand it, this allows the transmitter to continue sending a signal to the fence even though it is broken.

Step 4: Tune In

The fence emits a radio signal that is picked up by a reciever on your dog's collar when it gets in range, causing a warning signal or an electric shock. You should be able to detect this signal in the lower AM range. The signal of my fence was roughly 600 kHz. When tuned to the right frequency, you will hear the signal as you pass the radio over the ground. It may be necessary to turn up the intensity of the signal at the tranmitter, although I didn't have to (there should be a numbered dial somewhere on the transmitter, just remember to turn it back down later so you don't fry fido!)

Step 5: Find the Break

Walk the perimeter while passing the radio antenna over the ground where you suspect the wire to be. You should be able to pick up a clear, definite signal. The video shows me walking the radio back and forth over the line (in reality the signal was much clearer than it sounds, but you can definitely get the idea). When tuned in perfectly, the signal sounded like a rapid tapping/beeping - when tuned close but not right on, the signal caused the static to get louder as the radio passed over the wire. When you find an area where the signal drops out for a few feet, this is likely to be your break. Go slow and check the whole perimeter before you start digging, I found areas that seemed weak but when I eventually found the break it was pretty obvious.

Step 6: Dig It

When you've located the area where you suspect the break to be you'll need to expose the wire. I used a 3-pronged hand tiller and dragged it perpendicular to the wire, the invisible fence guys used a pick axe. Use whatever you like but be careful that you don't cut or knick the wire in the process.

Step 7: Check the Break

Once you've found a break, use the radio to check that you have a strong signal on both lines. I actually had two breaks but didn't know it until I found the first break and realized that one of the ends did not have a signal. I continued to dig in the direction of the dead line and found a second break a few feet away. If you have a strong signal on both ends connect them with a piece of wire, disconnect the choke and reconnect the wires from the fence into the transmitter. If the alarm goes off, congratulations, you've found your break!

Step 8: Mending the Break

The final step is connecting the broken ends in a way that is weatherproof and secure. I bought these connectors from the local hardware store, time will tell if they are the best ones or not but you want something that is waterproof and suitable for the temperature range in your climate. This type of connector is filled with silicone to seal the twisted wires. Once you're sure the fence is operating correctly, bury the mended wires and you're done! Good luck!

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153 Discussions

Step number one just saved me a fortune. I was given a quote to reinstall my whole fence because it is older. I found the problem and the fence is working with no digging required. Thanks!

I can't thank you enough! We just got a second dog and had a break somewhere on our 1/2 acre we have wired - after many downed limbs this spring, we were seriously doubtful of finding the happy we came across this website. Ordered the parts on Amazon for less than $20 and found the break in a very unlikely spot!

Before you go through all this, I'd suggest that you double check your transmitter. I have the Radio Fence Pet Safe RF-1010. It started beeping so I was certain that it was a line break. I did all these steps, and spent hours, then simply turned the dial all the way clockwise to 10. For some reason, the sensitivity changed from around 2 to 7.5 on the unit! Below 3, beeping, above 4 it went away! It now works like it did before, and it looks like the problem is solved.

1 reply

Glad I read this! Thanks! My kids probably played with the settings. I set the perimeter switch (a/b/c) back to B for under 1300’ wire length and diled it up until it stopped beeping. Tested with collar and it’s working perfectly.


10 months ago

Does anyone know the difference between the old and new pet safe systems? (The frequency maybe?) I have an older system. It looks like the one in this article. Pet safe is telling me I need a new system if I want new collars. The old collars are not available.

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I have used my invisible fence for going on 11 years with no problem..except today, fixing the chicken coop I accidently dug thru the wire causing the main box to continually beep, called the office number for the seller in my area. thankfully they are out for the thanksgiving week, I left my number and a message, then I decided to look on either Utube or instructibles websites for info on how to diagnose and repair the problem, BE very careful to note on the fine and coarse settings to be careful not to turn it back to the original setting set by the technician who set it up for you, I messed with my settings and shocked the "CRAP" out of myself SEVERAL times before figuring it out, "WELL" I didn't want to shock my dog so I had to try it for myself

Aren't there rules against advertising on this site?
There are many neighborhoods who don't allow physical fences as part of their covenant so no, you aren't better off getting a "real" fence. This is a good instructable that could save a lot of time and headache for someone.

Thanks for this Instructable. We found the break and our Beagle is happy to be off the chain.


2 years ago

Your local AM radio stations may or may not be close on the dial to the frequency the dog fence broadcasts. A cheap-o AM radio might work better than an expensive model (less sensitivity and less adjacent-channel rejection on the cheap model). YMMV so try different radios.

FWIW, the purpose of a choke is to pass DC current (measured in volts, so the fence system thinks a wire is shorted across the terminals) while blocking any AC (the noisy part that shows up in the radio is NOT shorted out, so it continues down the buried wire). You can make one -- it's just a coil of wire. Google it. Perhaps this system uses a constant DC voltage to test for continuity through the buried wire, and an AC signal (the "noise" you hear) to trigger the dog collar. A break would cause the beep that tells you the wire is broken (DC missing in the wire loop) and so you fool the system with the choke so you can test with the AM radio. Simply shorting the wire could diminish the signal to the radio, but I'd obviously try it and see if it's loud enough to do the job.


2 years ago

FORGET THE CHOKE. You don't need it. Just use a piece of wire in place of the choke and follow the instructions as provided. I plugged both a short piece of wire and the broken perimeter wires into the control box and it sent the 600 mHz frequency out the lines that was detectable by an AM radio tuned to 600. I have just over 1/2 acre inside my perimeter. Maybe the choke is useful for longer runs, but I did not need it.

With the RF choke the collar still works. I taped the prongs and used it.

With the RF choke the collar still works. I taped the prongs and used it.

Wow!!! Can't thank you enough for the detailed instructions!!! They were perfect - my luck was not so much. The hard part was finding an AM/FM radio - got stuck walking around with a hulking desktop radio from Target. With close to 2000' of wire, I started on the end that seemed the most vulnerable - I found the break about 150' from the opposite end, where the kids buried a dead bird. On the bright side, the large radio picked up a strong signal and I found the break on the very first dig - on the flip side, I had to listen to Rush Limbaugh for half an hour. :D

Thank you so much for posting this it saved me a fortune. I was able to get the RF choke from RadioShack for $1.50 and had extra repair tubes. It took me about an hour total that included running to RadioShack.

Why do you have to use an AM radio and fiddle around trying to find a suitable frequency? Why not just use the dog collar itself, which emits an audible noise when you get near the fence?

1 reply

If there is a break in the fence, the collar doesn't work. We're not trying to find the fence. We're trying to find the break in the fence.

Thanks for the info. I've had to do this in the past. Another tip: i bought old hoses at a yard sale or cheap at a dollar store. Using a box cutter, slice the hose along the length of the tube. Insert wire in hose and wrap loosely with electrical tape, then bury hose. It's time consuming, but I have never had a break in my dog fence since I did this!

Thank you, thank you, thank you! Had reserved the entire day to "Find The Break"...

5 minutes into "the entire day", I found the problem in Step 1! After doing the small loop, the transmitter reset itself. Problem solved}

I have a feeling you are gonna save me some money...


2 years ago

Just after the heavy rains that came through the Carolina's the alarm would not quit, no matter whatever tricks I tried. Kept walking the line with break finder over and over with no luck. Did the small loop as illustrated to check transmitter. It reset itself. Plugged my perimeter wires back in and our dogs let us know it was working right quick. Unfortunately everything was high when everything came back to life, and the dogs were not happy. Having to re-adjust the settings and work with the dogs in doing a little bit of re- learning. This tip worked great !!!!!