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

Picture of 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

Picture of 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

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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

Picture of 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

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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

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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

Picture of 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

Picture of 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!


d1no (author)2017-10-26

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.

TerenceH7 made it! (author)2016-08-14

It worked for me! I wish I had a stronger radio though

MamaLoca (author)2016-08-05

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

cgosh (author)2016-06-30

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.

KenB91 (author)2016-06-01

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.

DaveH130 (author)2016-05-31

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

DaveH130 (author)2016-05-31

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

mypawlak (author)2016-05-16

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

DaleO10 (author)2016-04-30

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.

DanG101 (author)2016-04-20

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?

KimR85 (author)DanG1012016-04-23

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.

ElizabethB128 (author)2016-04-20

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!

CynthiaC51 (author)2016-03-12

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}

adamtheestimator (author)2016-02-09

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

KurtR7 (author)2015-10-09

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 !!!!!

adamtheestimator (author)KurtR72016-02-09

I'll check that, first! Thanks!

gcmillerj (author)2013-05-26

To JoeysMom, I believe that PetSafe uses a different system and this procedure will not work with that system.
A friend of mine and myself are both very knowledgable in electronics and radio systems. We spent quite an amount of time trying to use the above procedure to find the break in my PetSafe system. It wasn't that we just couldn't find the break, the procedure just didn't work.
I started doing a lot more research on the Internet and believe that the PetSafe device uses a more complex system that does a better job, but requires specialized equipment to troubleshoot it.
I am checking into that now. I'll let you know what I find out.

huges84 (author)gcmillerj2015-11-01

I have a PetSafe and this worked for me. First make sure you do step 1 to confirm the transmitter is working right. Then when you wire up the choke make sure it's in parallel and has a solid connection. Crank the transmitter to its highest setting. You want an AM radio with an external antenna and you have to be right on top of the wire (inches to the dirt) to get the interference. You can't count on the frequency being 600Hz, you have to play around with the frequency to find the best one.

Hi! I´m developing a similar circuit for a home made robot-machine and it will help me a lot if I can see how your system is built, Can you upload a picture of the complete electronic circuit?

Markool6 (author)2015-11-01

Frustrated!!! I have a SportDog RF104A invisible dog fence. It recently began to alarm. I tried the short loop test and the results indicate a break in the line. I have approximately 600 LF of wire with about 60 ft exposed. I tried the AM radio test ~ actually using 3 different radios. I have never been able to get a static signal as it relates to my perimeter wire ~ it all sounds the same. I applied the same instructions shown in your pics, to no avail... Any suggestions... My dogs are used to it not working and do not leave the yard, but, we will be dog-sitting next week and she's a runner....Yikes!!! Help!!!

airedale01 (author)2015-07-06

I had a lightning strike that fried my PetSafe transmitter so I bought a new one. I followed all the steps and even tried turning the new transmitter up all they way as suggested in the comments. I thought maybe I had a break in the fence so followed all of these steps. Everything worked great, plugged in the RF Choke, hear the frequency on AM radio but cannot find the break. I've walked the fence three times and have strong signal the entire way around. Even re-did my splice just in case. Will a lightning strike cause some other problem. I'm considering just sucking it up and putting in a new fence line. Any suggestions welcome....Thanks

JaneN6 (author)airedale012015-09-21

I had a lightning strike in my yard as well. Sadly, I found so many spots where the line had been melted through/broken as a result of the strike. After half a day of mending the breaks, I gave up and replaced the wire. I was having repairs 6- 20 ft apart. I just thought that was too many repairs for my 1.5 acre yard. Good Luck!

csheerin11 (author)2015-06-05

Even thought Radio Shack local store said they had 3 RF Chokes...I drove there to find they had NONE! Tried making my own - didn't work. Finally just reset the switch on the side of the transmitter from High to Low and reset the dial to 5.... back in business. Possibly sent it into alarm state from the lightning storm we had the other day! Anyway... Only wasted 2 hours before doing that....(I also redid all my splices even though when I pullled each one apart and put them back together nothing changed on the open circuit alarm...)

CharlesW9 (author)2015-06-01

Kgburke (author)2015-04-12

I followed all the instructions but I cannot get the transmitter to stop beeping.
How long should it take to travel the loop?

rob.shakal (author)Kgburke 2015-04-25

Its immediate. Make sure you connected the electric fence wire tightly to each rf choke lead

rob.shakal (author)2015-04-25

Incredible! Thank you so much for this post! ! Worked like a charm. Under $2 for rf choke. Signal got weak in one section. Dug one foot each side of weak spot. It was a previous splice I had fixed 5 years ago when kids broke line digging for worms. Splice had broke. Redid and up and running again!! Took 15 mins. Saved hundreds.

lee.wimmert made it! (author)2015-04-22

Thanks this worked perfectly. There is a radio station at 600 where i live so a connected a 20 ft loop from some wire that i had. Thus way i could identify the exact sound. the sound get faint near the break so i put flags in the ground on both sides of the break at the last point where i had a strong signal. the break was in line between the flags. It was not very deep

robert.mielich.3 (author)2014-12-21

I bought the rf choke from radio shack. At first it seemed ok but a few minutes it my transmitter shut down. When I unhook the choke it works again. Any advice.

yes, there are instructions on your unit on how to reset it. The same as resetting your cable on your T.V.. Also if you have a large yard, you have to set it at six or about so the electric is strong enough to pulse through the entire length. Turn it up until it stops ringing, then very slowly, turn it down until it starts ringing, then turn it a centimeter.

Kgburke (author)angels412015-04-12

I tried turning up to 6 and then even higher and it still beeps.

BN3 (author)2015-04-04

What a great instruction! I followed this step by step and fixed the problem. After a period of time that the system was inactive, the battery in the collar needed to be replaced. Just make sure your battery is good so you can check the system accurately. Thank you very much for posting this.

hville (author)2013-11-24

Do you have to unplug the transmitter from the wall outlet to connect the RF Choke? If so, do you plug it back in before listening for the signal break?

angels41 (author)hville2015-01-26

of course it has to be plugged in. Don't worry it will NOT Shock you!

stepshadow (author)hville2014-01-13

I unplugged mine before hooking up the RF choke and fence wires. Probably just turning it off would be fine. Then you MUST turn it back on (and plug it in if unplugged) to listening for the signal from the fence wire.

ScottH5 (author)2014-09-13

great idea, can't wait to try it. QUESTION???? can't you just use the collar instead of an AM radio. Not sure I even own a handled radio anymore. Gonna try it and see. BTW - you are saving me loads of time and $$$$ THANKS!!!!!!!!

angels41 (author)ScottH52015-01-26

nope have to have radio. Hardest part is finding the radio, the rest is a piece of cake.

ConnieD1 (author)ScottH52014-09-20

The collar doesn't work when you attach the RF choke.

mary.l.conrad (author)2014-11-05

I can't seem to find the correct channel. My radio goes to 170. I scroll through the 54 through 65 area which I assume matches to 600? I just get static. Can anyone suggest something?

angels41 (author)mary.l.conrad2015-01-26

Static is what you want. The static fades when you get close to the break. My break was two ahead of where the fading started. Use headphones if nessicary.

cuyler.lanier (author)2014-12-29

Does this work if the break is where the wires are twisted together?

angels41 (author)cuyler.lanier2015-01-26

Of course, just go back six inches on each side and put in a new piece of wire.

gary.samvelyan (author)2015-01-11

Thank you so much. The paperclip method solved the immediate crisis and I can now focus on fixing the whole system. Your guide has empowered me to get this done.

msheppard (author)2014-11-09

Totally worked. Hard part is hearing the tone generated. First try I had to quit because the wind was too noisy. Dug up the wire up a foot or so from where I thought the signal dropped - and I was within 2 feet of the break. Turns out I actually had 2 breaks - one another couple feet down the line. Tied both up and now the dogs are getting their shock treatment.

Kml_s Lab (author)msheppard2014-12-07

must use head phone for accurate reading/

Beach00 (author)2014-12-05

Wow it worked. This is crazy. I was thinking no way I'd be able to find the break and my wife thought I was insane. I couldn't get my hand held radio to work so I used my Sony walkman headphones. My neighbors must have thought I was weird walking around the yard with headphones in my ears and the radio hanging an inch off the ground. I could tell the slight change in static on channel AM 600.

Thank you for the post you save me a lot of $$$

brodiemac (author)2014-10-28

This worked great! While my fence didn't have a break, it did have a short that caused it to fail. This method didn't find the exact location, it did narrow it down to a length of fence where I knew there was a union between to sections of wire. Once I located that, I found the short and was able to fix it. Thank you!!!!

ConnieD1 (author)2014-09-20

I have an Invisible Fence ICT 700 Transmitter. I did have a problem until I was able to locate the Operation and Installlation Manual for this on the internet. I was afraid I was going to break the signal field wire connectors by pushing on them too hard. Once I figured it out the rest was easy. I did have to have the AM radion on the ground almost to detect the wire. It was no problem since I was using head phones that had a long cord. This repair saved me at least $98!

skram1992 (author)2014-04-21

I have a PetSafe Stubborn Dog fence. It has been installed for about two years. After reading all the comments and checking other sites, I was a little apprehensive that this would work, but thought I would give it a try. Spending $2 was a lot better than ordering a locator for at least $50 and waiting for it to come in. I'm pretty sure my dogs would have figured out the fence wasn't working soon. Hooked up the choke and tune the radio to around 600 on AM, it instantly picked up the transmission. Hooray! I then went outside and started walking the 1300 feet of fence. I really don't know how far the signal will reach, it was still transmitting at about 500 feet. I was pretty sure I was in the area where it was spliced so I started digging. My son then took the radio and walked to see what he could find. The signal was good and then he discovered our problem. Something had chewed and broken the wire. I didn't see that on my two visual checks, don't know how I missed it. We also used the radio and with it stopped when going over the cut part. We had an easy fix from there, hardest part was covering the wire I had dug up. Time and effort wasted on my part, but good news is the choke and radio worked with our fence. Now I am prepared if we do have an underground break in the fence. Thanks for sharing this solution. It definitely is better than ordering the detector from the company.

PJMc2 (author)2014-04-19

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.

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