Creating Gaps in the Dog Fence

by Gajan Retnasaba on February 26, 2011

A reader makes an interesting suggestion for creating gaps in the dog fence wire by having a second device that deliberately causes interference.

It’s funny to read how many people want to create dead zones in the loop by just splicing in a length of twisted wire. You’re so patient with your explanations – much more so than I would be! However, this problem seems to come up again and again and I did a little brainstorming…. tell me what you think.

Like I said, everyone seems to want to try splicing in a twisted section in the main loop or putting some kind of shield around the wire, but you always respond that it won’t work. As I read through the comments it was the same thing over and over, but one poster’s idea on another page caught my eye – he asked about doing a “triple twist”, where the wire doubles back on itself, and then doubles back again, continuing in the original direction. I got excited as it seemed like a brilliant idea, but then you replied that it’s been tried and wouldn’t work I don’t understand exactly why, but I suppose it’s because the second cancels out the first, but the third is not canceled by anything… (I’m not a physicist, I’m just guessing). Well, taking that poster’s idea one step forward, and doubling back a third time, creating a “quadruple” twist, it would not create a signal and the dog could pass the wire. Now of course, this “quadruple twist” idea isn’t very clever at all – it doesn’t solve the problem of creating a dead spot in the loop, but if I’m right it does seem to show that an “odd” number of wires will create a signal, while an “even” number won’t (of course, this is all assuming there are no three-way splices anywhere – they would all have to be independent wires).

So what’s the big deal about that? Well, it made me wonder about ways to get that second wire in there only for the short distance where you want the dead spot and nothing more. Well, I’ll tell you that I’ve thought about it, and no matter what you do, you can’t get the main loop wire to do that, no matter how fancy you get.

Now finally to the interesting part: As I read through the posts, I see some people complaining about having the exact opposite problem – *unwanted* dead spots created by other, unrelated wires (such as low-voltage lighting systems nearby). This got me wondering if you have heard of anyone installing some kind of low voltage lighting system and running the wire in the same trench as the fence wire (or even twisting them together) to *intentionally* create a dead spot, say, at the back entrance to a house like so many posters seem to want to do? My intuition tells me this might actually work, and might be easier than the “deep burial” method, the “gutter” method, or the “double loop all the way around the yard” method you usually suggest.

Of course, it would require the purchase of some other product, but with some experimentation, it seems we as a community could figure out that, for example, “Patio Lighting Kit number 345B from Home Depot” (not a real product – I just made that up) provides the perfect voltage to cancel out the fence signal if the wire is buried right next to the fence wire.

What do you think?

Marc

ADMIN – Hi Marc,

We do indeed get a lot of creative ideas on how to create dead spots in the loop!

You are right, even numbers of wires like a quadruple or sextuple bundle will exhibit cancellation (although as you realized even numbers are unhelpful if you are trying to continue the loop) and you will get no signal. Odd numbers have an active signal because the evenly paired wires going in opposite directions canceling each other out leaving a single wire that will create a signal.

The idea you have to have a separate device that creates a canceling signal is interesting. The challenge would be to have a device that perfectly canceled the dog fence signal without creating a signal of it’s own. Often when you have accidental cancellations caused by for example neighboring dog fence systems, the cancellation is not completely consistent and you get small pockets where the signal is present.

{ 6 comments… read them below or add one }

Diane September 25, 2011 at 2:01 pm

We have been working on installing our underground dog fence today. We have it all laid out and have twisted the wire that runs along the back of our house. When we tested it the twisted wire does not cancel the signal. Why would this be?

ADMIN – Hi Diane,

The twisted wire only works if it is used in specific ways. It is primarily used to connect the transmitter to the main loop – it cannot be used as part of the main loop to make one side of the loop non-active.

A good rule of thumb is that every connection in the dog fence system should be one-to-one, if anywhere in your layout you have three or more wires connecting it is not going to work properly. For more information see the twisted wire section on our website.

I am guessing from your description that you ran the twisted wire along the back of the house to do a backyard only layout. You won’t be able to achieve this using the twisted wire, but there are other ways to do it. For more information check out our dog fence layouts page.

Richard Riel September 3, 2011 at 1:28 pm

How about using metal conduit. Insert twisted wire, or regular wire in metal conduit of needed length and burying the conduit below the ground surface, and continuing with fence wire. this will eliminate any radiation for what ever length of conduit you use.

ADMIN – Hi Richard,

In our experience metal conduit does not seem to disrupt the signal. Occasionally it will do something odd like magnifying the signal, but we don’t get a nice clean break that would make it useful as a technique to create dead zones.

Teresa Bloodworth August 24, 2011 at 6:12 pm

OK, guys. Here’s one for the girls. What about running double wire, begun at opposite poles all around the perimeter, perhaps a foot apart, then bringing it together and twisting wherever you need a dead spot? A little more work and expense for twice the wire, but definitely better than digging a 3 ft. trench, or a whole set of low-voltage lights that “might” work. Whaddya think?

ADMIN – Hi Teresa,

Clever. That would work, but on the active sections you would want to keep the wires six feet apart.

Robert Froch June 8, 2011 at 9:06 am

Very informative tips. Thank you for this post.

Bill Truex April 12, 2011 at 4:17 pm

What if I was To pass the untwisted wire thru a tube such as pvc and buried 4 to 6 inches underground would that not create a dead zone?

ADMIN – Hi Bill,

Unfortunately passing the dog fence wire through tubing has no effect. Burying the wire deep does deaden the signal, but you will need to go at least three feet down, possible more depending on your solid type and how wide you set the boundary width dial.

It is usually easier to modify your layout to create the dead zone. Email us a diagram and we can usually help you figure something out.

bill driver March 30, 2011 at 7:14 pm

need to put a dead zone in a low volt RF signal wire.

Admin- Hi Bill,

Unfortunately you can not create a dead zone in the middle of the boundary loop. Please view our planning page for more help on the layout.
(http://www.dogfencediy.com/installation/plan/)

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