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!
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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.
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msheppard1 month ago

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.

must use head phone for accurate reading/

Beach0013 days ago

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 $$$

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?

brodiemac1 month ago

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!!!!

ConnieD12 months ago

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!

ScottH53 months ago

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!!!!!!!!

ConnieD1 ScottH52 months ago

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

skram19928 months ago

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.

PJMc28 months ago

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.

hville1 year ago
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?
stepshadow hville11 months ago

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.

stepshadow11 months ago

I made my own RF choke since I live in a rural area and I couldn't get a Radio Shack RF choke for at least a week. Quite easy to make one yourself. I used the calculator on this website to make an air core RF choke.

I made mine using a spool from some wire I had bought. It's almost 2 1/4 inches long, the diameter is about 3/4 inch before any wire is wrapped around it. Then I counted the number of turns of wire I put on it as added wire. I think the final "average" diameter was a little over an inch so I used 1.1 inches as the diameter. According to the calculator, I needed about 100 turns (slightly less). I hooked it up to the transmitter along with the underground fence wire. It worked like a champ. Not very pretty, but functional. As I approached the wire break, the signal became very weak on the AM radio. The radio needed to be held close to the ground.

This worked beautifully! I wish I'd found this last summer, when my husband and son spent hours locating the break(s). We only had to purchase the RF choke from Radio Shack for $1.49. We already owned an old AM/FM radio, so no extra expenses. Another poster mentions a device made for this, but it costs $150! I'll stick with the $1.50 and AM radio! Our biggest problem is not with splices but more with a neighbor with OCD that likes to run his edger and rototiller close to our property line. This last time he was adding on to his garage and tried to bury our wire with his shovel; he broke the wire twice! I hope the fence still works if we bury it in conduit this time!
I have an Invisible Fence brand and so does my neighbor (it was installed when I bought the house). Right after I moved in I was aerating the yard and cut both his and my fence. I called a friend in the landscaping business (who told me he cuts/repairs them almost daily) to come out and make the repairs. He said he could make it but would take a couple of days. The next morning my neighbor had the Invisible Fence people come out and fix his fence and then stuck the $150 paid invoice in my mailbox with a note saying I owed him the money. My friend came out the following day, had the 4 breaks in my fence repaired in less than 30 minutes and didn't charge me a dime. A few weeks ago, my neighbor had tree surgeons topping trees in his back yard and when the trucks pulled out they swung wide into my yard and my fence started beeping. I didn't have time to deal with it so I unplugged and kept the dog inside. I'm now trying to repair it myself. I guess that is the more neighborly thing to do???
riplefct1 year ago
I need some help. I have followed all the instructions. Have the choke on. With it off, I have beeping. With it on, beeping stops. With the choke on (exactly as above), when I wave my radio over the wire right at the box (above) I hear the signal. But the rest of the wire has no sound at all. It is as if the signal is not going down and out the line. I can trace the wire out of the house, and even there near my garage I hear no sound in the radio. Any advice appreciated.
pamsy631 year ago
Besides being much easier than the Petsafe instructions these instructions worked like a charm. I located the break (probably due to manually removing weeds in the grass) and fixed it in less than 2 hours. What a relief after 2 weeks of our dog jumping the fence to chase rabbits!!! Thank you so much!
By the way my system is a Petsafe UltaSmart inground fence system, so it does work on it.
monsoon2251 year ago
Worked perfectly. I too used a bolt and copper wire. Radio frequency was a little off until I noticed a station coming in tune each time I was over the buried wire. Found the break on the first shot. Thank you!
wadams41 year ago
In further looking over for options on the internet, I've found the $100-$200 wire break detect products range limited to 1000 ft. The Dogwatch team who did the repair used a Greenlee 501 product where the range goes to 4000 ft. (A distance that would cover a range of shapes for 6 acres). The only downside is the product is >$600 and a questionable investment I'm mulling over, for only home use with infrequent issues.
wadams41 year ago
In further looking over for options on the internet, I've found the $100-$200 wire break detect products range limited to 1000 ft. The Dogwatch team who did the repair used a Greenlee 501 product where the range goes to 4000 ft. (A distance that would cover a range of shapes for 6 acres). The only downside is the product is >$600 and a questionable investment I'm mulling over, for only home use with infrequent issues.
wadams41 year ago
I have a dogwatch system for 6 acres. I tried the RF Choke method with a AM radio and due to size of property, could not make locate the break. The signal became too weak at the longer distances. I tried the method with Dogwatch transmitter set to FM settings (on back of unit), the signal pickup is on AM radio. I also tried the method with transmitter set to AM (on back of unit). On FM, the signal is loud interference, on AM the signal is a pulsing one with interference. I gave up after 3 days and called in Dogwatch to find/repair the break. They have pro grade wire break detection equipment, amplified signal transmitter (independent from the fence transmitter) and a receiver with very sensitive pickup. They were able to walk the entire perimeter with a strong signal, no fade out like the AM/RF Choke experienced, in the wire up to the break. Overall, I appreciated all the info to try a DIY and save $$.

Knowing the chance of having more fence breaks, I'm looking into the DFNA device set (and will look at the buying in China to save $$$) . What I'm trying to sort out is whether the unit works up to 1000 ft or up to 3000 ft. In different places on the web, it is listed as 1000 or 3000 . Would appreciate to see more field experience in this thread about property size of length of wire.

Also, any other methods to save $$ will be good. E.g., make your own amplified transmitter that can be picked up on AM band for sizeable properties.

The sequence of pics for the post are great for newbies in trying this out.
FWIW, at radio shack, bought the choke for $1.39 and AM/FM small radio for $14.99 .
Cost here in central MA for Dogwatch fix and repair is $100 which includes upto 2 splice repairs (with materials), more fixes would be $12 each.

Separate issue, but somewhat related....trying to find something. One of our dogs lost a collar with the receiver. Dogwatch has a wide-spread scanner unit to detect it...a future visit. Dogwatch provides lifetime replacement and or rebates for damaged units. So even though I had to buy another receiver, when I find the lost one, I will get reimbursed.
mx007911 year ago
I followed the instructions and was able to find a signal where the invisible fence begins and down about 1/4 of the fence line. going both directions I lost the signal outside of that section and wasn't able to find it again anywhere in the remaining 3/4 of the fence line. If there is more than one break, is this what you'd expect?
If you have a surge protector, save yourself a lot of time and test your fence without the surge protector FIRST. I did a lot of splice replacing and bought a new receiver THEN figured out that the problem was not in any component of the fence, but in the surge protector!
gcmillerj1 year ago
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.
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?
Hi lgrah760! Can you upload a picture of the complete circuit? I´m developing a similar one for a home made robot-machine. It will help me a lot if I can see how it is built.
Co Diesel1 year ago
This worked great. I just installed an underground fence on 6 acres of our property and as soon as I connected the transmitter I got a fault alarm. Checked with a small loop and all was well, disconnected the twisted pair from the main loop and wired the twisted pair together and all checked out fine. So I was really stumped as to how to find a break somewhere in just over 5000 feet of wire. Bought the rf choke at Radio Shack for $1.49 and a $9.95 am/fm radio at Walmart and I was in business. The radio I bought only works with ear phones (no external speaker) and for me that actually helped because I could isolate the sounds. With both wires connected to the choke I got a very clear pulsing sound. I never lost the sound in the entire loop but there was a spot where the volume diminished dramatically. So I figured that was the area. I disconnected one wire from the choke and walked the line again. Note that at least for me with one wire disconnected all I got was loud static, not the pulsing sound from before. The one wire method helped me find the exact spot of the break (it was where the volume diminished on the two wire method) but this was very clear as the static stopped completely. In my case it was a poor splice. I fixed it in two minutes. In all it took me 30 minutes to find and repair the bad splice and this was on almost a mile of fence. It took longer to drive to town to get the rf choke and the am/fm radio. Thanks so much for the original post with great pictures.
K_DePew1 year ago
Might I suggest: When I tried hooking both ends of my underground wire to the RF choke, I kept missing the break in the line. The break separation was so narrow that I would pick up the signal from the other side of the line. Ultimately, I had success by hooking up only one side of the underground line. I first found the break (actually two breaks) by connecting only one side. I then connected the other side to verify where the breaks were.
DICK WEED1 year ago
Hey voytek011 did you figure out you problem? I'm have a similar one where the transmitter emits such a strong signal that I can't tell where a problem with the wire is. When I try a short loop it seem to work correctly. Is this a twisted pair problem?
there are small levers above the transmitter wires. they must be pushed up to release the wires.
Worked like a charm. And regarding the collar idea, I also tried that first, but the signal was too faint for my collar to pick up. Also, my daughter's Hello Kitty am/fm alarm clock did not work very well either :) So I picked up a Grundig Mini400 handheld radio, around $30 bucks at Radio Shack, it worked perfectly for this application, just point the antenna down toward the boundary and followed it all the way around my yard directly to where the break was, amazing! I could return it, and then that would mean this idea only cost me as much as the rf jumper, so THANK YOU SO MUCH Igrah760. I probably keep this radio though for future. Good to know about a dedicated locator that is out there, but this also worked so I don't think any reason to get down on this technique, it took me about 5 minutes to add the jumper, super duper easy, it obviously works!
JoeysMom2 years ago
I see this is an old thread,..I'm hoping someone is still reading it. My PetSafe Stubborn dog fence is no longer activating the collars. The loop light is still on,.I did a loop test with 10 ft of wire and that works fine. When I 'test" the system by trying to turn the knob counter clockwise until the lights go out, they never go out, new batteries in both collars and again it works with 10 ft of test wire. Will this RF choke trick still work?
voytek0112 years ago
I have tried the RF choke method and have the following problem.
After installing the RF-choke method I get a tremendously strong pulse on my AM radio. The pulse is present even over the twisted wires or when standing next to the transmitter - that can't be right? Any idea what is wrong with that?
When I walk along the wire the signal remains strong and only when I stray far from the wire path it starts to fade. I tried to turn down the field width/size etc but to no effect.
Any suggestions? I'm running out of ideas.
Grant Fair2 years ago
As I understand it, the "fence" consists of a piece of wire with two ends. The ends attach to the transmitter.

If this is the case, your statement "to verify that there is a break ... use an ohmmeter and check the resistance on the disconnected wires. If there is no resistance the wires are continuous" is mistaken.

If a wire continuous, it does have resistance, which the meter will show. If there is a break in the wire, the ohmmeter will show no resistance.

kgl06293 years ago
I have an issue with my transmitter for the PetSmart 125 REV 02. We had a major thunderstorm last night that shorted out the fusible resistor labled R29. Does anyone know where I can order one from, Petsmart customer service is closed today (Sat) so I will have to wait till Monday to see if they can help. Any help would be greatly appreciated. Thanks
Did you ever locate the correct resistor? I read the color code on mine (one side was still visible after it blew). Red =2, Yellow=4, Brown=X10 multiplier, Gold=+-5% tolerance. So if I did that right it's a 240 Ohm 5% resistor. Now I'm trying to determine the wattage so I can order the correct one.

If you trace R29 it connects directly to the middle Boundary line terminal. The label on the back of the transmitter reads Output-AC 12V 830mA. If Power=Volts times Current, then 12V X .83A equals 9.96Watts. Is it safe to assume the resistor is 10W based on the output listed or is there another way to determine the wattage of a resistor?
danoftroy2 years ago
This was a very helpful tool that does work, but please read the entire post to tell you how I finally fixed my problem.
First, my setup. I have a Petsafe Stubborn Dog unit which has worked outstanding for about 2,500 feet of wire covering maybe 4 or 5 acres. It has worked great but then one day there were problems, which I could not pinpoint. The collar had no signal, although the box was not indicating a line break.
I purchased the RF Choke from Radio Shack, which they had in the store for $2, and I also purchased a Radio Shack AM-FM radio for $15.
It took a while to recognize the "chirping" sound, which was between 0-600 AM frequency, the best signal coming in around 550 AM.
This was also next to a minor league baseball game being played by the Gwinnett Braves and the Toledo Mudhens, which Gwinnett rallied for a run in the 7th inning to break a 2-2 tie and win 3-2, despite a 3-5 hitting performance by Toledo centerfield Quinten Berry.
But I digress.
So with the AM radio "chirping," it really sounded like a cricket chirping really fast. I followed the underground wire for some time, but again this is a long run, and eventually the signal became so weak the radio would not pick up the signal. I finally determined that the radio picked up the signal for half the wire and there was no signal for the other half.
I now questioned many things. Was my box bad? Was the collar bad? Was there not a true break in the line but a nick or fault?
I then called PetSafe customer service. The young lady walked me through a 10-foot wire "loop" test with my box and it proved the box and collar were both in excellent condition.
I then regrouped, and began replacing every splice that I knew of, and there are probably 10 or more in all due to previous breaks and original splices.
I then turned the box back on to test, after I had replaced maybe 6 splices, and boom, it was working better than new. I had a signal that would cook bacon.
So the moral to my story is something I hope you will remember - replace your splices first, before you spend any money on an RF choke, a radio, more wire, a service call, or a Taylormade Burner Superfast 2.0 driver. The driver has nothing to do with this, but you can't play golf while you are trying to fix a dog fence. That's my point.
I also will continue to use the RF choke and radio in the future, as it does detect a break and weak signal strength, so I do recommend it. Just remember to check your splice connectors first.

Hi! Awesome info but before I starting racing down the rabbit hole, here is what I am dealing with: New Battery in collar; should be working as it "beeped" upon securing. Light flashing on my Invisible Fence LP3000 indicating power on. No alarm has ever sounded to indicate a break in the wire yet collar does not beep anywhere along fence perimeter (enclosing about 1.5 acres). Took covers off and dusted off cobwebs. (Not too bad for a 10 yr item). Tried turning up juice on "fine" and Coarse" switches but still no audible or physical signs of working with the collar. Dog savvy to problem (darn!) So, if no alarm has sounded, is it still possible that I have a break in the fence? I, too, was turned off by the $100 for the first 15 min and $75 per hour service fee. Thanks for any advice!!
Well you could save all that time and digging by simply purchasing a product that is designed specifically for this purpose. The DFNA Locator from Dog Fence of North America is by far the quickest and easiest way to locator problems in your underground fencing. I don't know about anyone else but my time is worth something and if I have to do all this to fix a simple wire fault. You can find the corr4ect way to splice dog fence wires at:

If the proper splices are used correctly then you won't have splice problems in the future.
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