How Underground Pet Fences Work

While the exact date of its origin is unclear, the underground or wireless pet fence industry started to gain momentum in the early 1970s. Each brand of underground or wireless pet fences has its own history and interesting story. The industry originally began as a way of both protecting pets and making image-concerned owners happy and has become a wildly popular in recent years. Today's larger, underground or wireless pet fence companies have grown through professional resellers and distributors located across the country. A search in your local Yellow Pages will probably lead you to a reseller or distributor just around the corner.

Underground or wireless pet fences are intended to be a correction deterrent to your pet, not a punishment. Many of the more popular systems are endorsed by national humane societies and animal organizations such as the Humane Society of the US, the ASPCA, vets, vet publications, animal behaviorists, and major university veterinary schools.

As suburbs continue to pop up around cities and as more neighborhoods and subdivisions are formed, so too are restrictions. Many homeowners associations have policies that restrict the type, size, and existence of any fence system. At the same time these associations also restrict the freedom of pets. Underground or wireless pet fences make the association and the homeowner happy. The homeowner is able to contain the family pet and the association is happy because there isn't the visual clutter of conventional fences. Even without restrictive covenants, you may still choose underground or wireless pet fences because of aesthetic appeal.

In addition to covenants and aesthetic appeal, underground or wireless pet fences are growing in popularity because of the comparative cost. Consider the following estimates* based on a self-installed, 1/2 acre (500 foot), perimeter enclosure for two pets (for simpler calculations, no pools or gardens are included):

	Wooden Privacy Fence	Chain Link Fence	Basic Underground Pet Fence
Materials	63 Treated 6'x8' sections ($25): $1575 63 8' long 4x8s ($7): $441	10 6'x50' rolls ($60): $600 50 10' top rails ($6): $300 50 6' posts (6): $300	**Pre-packaged Basic Kit: $159
Accessories	Corner posts, 4' walk gate and hardware: $150	Section connectors, corner poles, 4' walk gate and hardware: $200	Additional Receiver Collar: $60
Labor	64+ hours (8 hr./day for 4 Saturdays & Sundays)	64+ hours (8 hr./day for 4 Saturdays & Sundays)	2-3 hours/500' of fence
1 Year Maintenance	Replace rotted or damaged sections occasionally	Patch tears in the fence	8 6V batteries ($6): $48 Replace every 3 months
Total Cost	$2166 + Your Time	$1400 + Your Time	$267 + Your Time
*Prices from a home-improvement warehouse **Basic Kit includes 500' of wire and accessories, 1 collar, and 1 installation and training video

Most underground pet fence systems consist of three components:

• A transmitter
• Underground wiring
• A lightweight receiver worn on your pet's collar

A sample layout of a yard using an underground pet fence. This layout illustrates the many ways that the underground fence can work for you. The driveway and sideways represent areas for your "invisible gate."

Each component is described in the following sections.

The Transmitter

A transmitter mounted on a brick wall in a protected area.

The transmitter must be mounted in a dry location (such as a garage or shed), near an electrical outlet. Mounting the transmitter is really easy. All you'll need is a few screws to hang the transmitter on, a screwdriver, and the electrical outlet.

Most fence systems come with either a standard or deluxe transmitter, with the main differences being how much area each can cover and the correction options.

The transmitter plugs into a standard electrical outlet. It emits a radio signal that travels through the installed underground wire. Therefore a transmitter can accommodate as many pets as you have collars.

Remember that while underground pet fences are meant to keep your pet in, they cannot keep other pets out. If you have a contained female pet that goes into season, it is strongly recommended that you speak with your vet as soon as possible to discuss your options.

The buried wire is just that -- a single strand of insulated wire. It makes a big loop from the transmitter around your property and back to the transmitter. Prior to installing the wire, you may want to layout your boundary with either spray paint or a garden hose. This will give you a more visual representation of where your system will be. Skipping this pre-planning step may require extra digging on your part later should you decide to move the boundary.

You need to bury the wire 1 to 3 inches below the surface of your yard. Although the system still works if the wire is not buried, the probability of the lawn mower cutting the wire or someone tripping over it is 100% if you do not bury it.

Spool of 18-gauge, multi-stranded wire

Most basic underground or wireless pet fence kits come with a 500 foot roll of 18 gauge multi-stranded wire, wire nuts and a wire fastener. The 500 foot roll of wire is sufficient for about 1/2 acre of land. If you prefer to fence in a larger area for your pet, you can purchase additional packages of wire and training flags at a minimal cost.

You should also know that when laying the wire around your yard, you can also enclose swimming pools, vegetable/flower gardens, or any other area that you don't want your pet to access. This is done by twisting the wires together between the secondary enclosure (the pool or garden) and the primary enclosure (your yard), as seen in the image above. Twisting two wires together cancels the signal, allowing your pet to roam freely between the boundaries of each enclosure.

Photo courtesy The collar

Most basic underground or wireless pet fence kits come with one waterproof, lightweight receiver and a collar. If the included collar is not the right size for your pet, you can buy a collar at your local pet store and put the receiver on ­it. For each pet that you wish to keep within the boundaries, you must purchase an additional receiver and collar kit. Any other pet or stray animal that does not have a receiver collar will not be affected and is free to come into your yard.

The receiver is powered by a small 6-volt ­battery (as seen in the above photo). Most kits come with the first battery, but you must replace the battery at least every three months for it to remain effective.

HINT: When replacing the receiver batteries, visit your local superstore or drugstore and go to the battery aisle. You'll find 6-volt batteries there for much less than in pet stores or home-improvement centers!

The idea behind all underground pet fences, regardless of the manufacturer, is the same. In all of these systems the transmitter uses the buried loop of wire to broadcast a radio signal. The signal is normally very simple -- just a sine wave, or possibly two sine waves at different powers. As described in How Electromagnets Work, the buried wire acts as an antenna and turns the signal into electromagnetic waves.

The transmitter does not use a lot of power, so the signal around the wire has a very small range -- perhaps 10 or 15 feet. In some systems the wire has two signals running through it -- one at low power and one at a higher power. In these systems the collar can detect different distances from the wire to provide different levels of correction.

Inside the collar is a small radio receiver (essentially an AM radio very similar to a $5 battery-operated AM radio you would buy at a discount store). When this radio gets close enough to the buried wire, it receives the signal that the wire transmits. The radio triggers a correction so the dog knows it is nearing the boundary.

The underground wiring installed around the perimeter of your yard loops back to the transmitter that you have plugged in a safe, dry location (it is also recommended that you install a lightening rod near the transmitter to prevent blow-ups). See the sample layout for an example of this looping. The transmitter controls determine how wide the electric field is from the installed wire.

Patent #5,207,179 describes an underground pet fence in a good bit of detail if you would like to learn more of the specifics of an individual system. Many of the patents it references are also good.

An underground pet fence is basically a psychological device. It cannot harm your pet. In fact, underground pet fences often have no deterrent value at all unless combined with training. You need to teach your pet where the boundary is, and inform your pet that going past the boundary is bad. Once you establish the rules, the collar is there to remind your pet about them when you are away.

The collar reminds your pet using different levels of correction, and how the fence system corrects your pet is up to you. Most underground or wireless pet fence companies offer two types of transmitters -- standard and deluxe -- and the correction options vary according to which transmitter you have. A basic transmitter can cover up to 25 acres of land and offers only a "warning and correction option." The advanced transmitter can cover up to 100 acres and offers three operating modes: "warning," "warning and correction," and "correction only."

With either type of transmitter system, when your pet gets too close to the boundary, its receiver will begin to beep -- this is the "warning." The closer your pet gets to the boundary, the slower the beep gets. If your pet ignores the warning and proceeds toward the boundary, the receiver will emit the correction of your choosing -- static electricity or a spray of citronella.

The static correction is similar to a static shock you get when you shuffle your feet across carpet and then touch a metal door handle. Citronella is commonly used in the candles you put on your porch or deck in the summer to keep the mosquitos away. It has a spicy, citrus smell that your pet's sensitive nose will find annoying. Neither correction is harmful to your pet. Rather, your pet will begin to associate the correction with the area in your yard where the boundary is.

How Will My Pet React?
With training, your pet will ideally retreat immediately once he hears the warning from his receiver. However, many pets will -- at one time or another -- test the boundary. Your pet will probably react in one of two ways:

• RETREAT!!! (usually with tail between hind legs)
• Hunker down and wait it out

Of course, you want your pet to retreat, not to wait around. A pet who "freezes" when the correction is delivered is being continually corrected, and that isn't pleasant for the pet or the owner. If this occurs, re-train your pet with a leash and teach him to retreat to back into the yard when he hears the warning.

Underground pet fences should not be used as a replacement for obedience training, but as a supplement to it.

With the proper training, your pet will quickly learn to adapt its behavior to avoid the correction. Although the training age varies from breed to breed, generally speaking, you can begin training your pet when it's between five and six months old. Most underground systems recommend that you let your pet wear a deactivated collar for a week prior to training so that he gets used to the additional weight on the collar.

Train your pet on a leash so that you have control over what happens. Most pets have been walked on a leash and are used to it. If you don't typically use a leash, you may want to train your pet to use one by gradually walking him/her on it in gradual increments of 15 minutes, or until the pet is comfortable with the leash. Be patient with your pet -- remember that your he may be hesitant about this new "thing" you're introducing him to.

Training with the underground pet fence involves boundary flags, the correction training, consistent training, and what is known as the Dummy Collar Effect.

• Boundary flags: Boundary flags will serve as a visual training aid for both you and your pet. The flags should remain in place for at least two weeks, but in some cases as long as 30 days. Your pet will eventually associate everything inside those boundaries as its safe zone, the area where your pet can roam freely without getting a correction.

• Correction Training: The first time your pet receives a correction should be on a leash. This enables the owner to easily redirect the pet to the appropriate behavior should the pet become startled or confused.

• Consistent Training: Some pets are more stubborn than others and need the system to be on all the time to contain them.

• The Dummy Collar Effect: This is where the activated collar is eliminated as a learning factor, typically for three to seven days. This way, the pet learns to avoid the yard boundary altogether. If you have a stubborn pet, this probably is not the best training method.

When training your pet, you are teaching him that the beep he hears when approaching the boundary should be associated with the correction he will receive if he proceeds toward the boundary. You will teach your pet to retreat from the beeping and the boundary by pulling him away from the boundary when the correction signal goes off. Your training video will explain this in more detail.

A dog working under a lot of adrenaline can power right through the fence barrier. The more they're trained at the beginning, the less they're inclined to try it. Also, an obedience-trained dog, regardless of how much he wants to "come" when you call, will hesitate or even refuse to return to the yard. If you know that somehow the dog has gotten out with the collar on (e.g., during a power failure), turn off the fence until the dog comes back. When the dog returns and is safely inside the yard, praise him and then quickly turn the transmitter back on.

One final note on training: It is important that your fence have what is known as the invisible gate, such as a driveway or sidewalk. The invisible gate should be the one place that, with you, your pet can cross the boundary without correction. To teach your pet where your invisible gate is, take the receiver collar off, put your pet on its leash, and walk your pet through the invisible gate. The first few times, your pet may be very reluctant to cross over the boundary. But once your pet learns that the collar is off and that you have given it permission to cross the boundary, the underground pet fence will be set. Your pet will quickly learn that when the receiver collar is on, the invisible gate is shut.

The underground system is probably the most popular pet fence system used today, but wireless systems are also available. Many neighborhoods or subdivisions that restrict the use of conventional fences agree to underground or wireless pet fences because the systems don't alter the appearance of the neighborhood in any way. Underground or wireless pet fences are comparatively inexpensive and easy to install, and -- with the proper training -- very safe for your pet.

Installation can either be done by you or a professional (consult your Yellow Pages or get a reference from your vet or pet store). If you choose to install the system yourself, you may want to seek the help of friends or neighbors, especially if they have experience installing their own fence. You will need some tools for installation.

Underground pet fences can be a welcome addition to your home and can make the owner-pet relationship more pleasant. These systems:

• Guard against unwanted pets in your flower/vegetable garden, as well as around your yard
• Require much less maintenance, are easier to install, and cost less than conventional fences
• Protect escape-artist pets from escaping yards with existing fences
• Give you peace of mind when your pet is outside

But that's not the whole story.

Underground pet fences will not work in the following situations:

• An underground fence cannot contain an untrained dog. If you do not have the time to train your pet, or if your pet is totally wild, an underground fence is probably not for you.
• An underground fence keeps your pet in but will not keep other pets out. If you have a female dog or if other dogs in your neighborhood roam free and like to fight, an underground fence is probably not for you.
• Underground fences cannot protect your pet without power. If power failures are common in your area, look for a product that contains a battery backup in the transmitter.

It is important that you understand that after you install (or have a professional install) an underground pet fence, there is occasional maintenance required on your part. You will need to:

• Train your pet that staying in the yard is the safe and correct way to avoid the correction
• Monitor whether the wire that provides the "unseen" fence is intact and has power. Many models come with lights that remain lit unless the connection is broken.
• Test the receiver regularly to be sure that the battery is functioning or simply replace the battery on a strict schedule (while most underground pet fence companies recommend that you replace the battery every three months, some will send you replacement batteries at some fixed interval if you have their fence system!).
• Shave a small patch on the neck of densely coated dogs on a regular basis for the collar correction to work.

Be aware that even intelligent dogs who like to escape will test the fence occasionally. This should serve as a reminder to shave the neck and/or replace the battery.

Ultimately, you should consider your budget, personal preference, your pet's size and temperament and local zoning laws.

For more information on underground pet fences and related topics, check out the links on the next page.