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Electric fences
There are simple ways to prevent conflicts with them near our homes and businesses. Many of these are outlined in the solutions to human - bear conflict page. If attractants have been cleaned up as much as possible and contained and bears continue to frequent the area, an effective preventive measure is the use of an electric bear exclusion fence.
Remember: Electric fences are not a solution for poor food or garbage storage or lack of normal safety measures in bear country. They are most effective when other safety precautions are also in place.
Why use electric fences for deterring bears?
How safe are electric fences?
How do electric fences work?
How much does an electric fence cost?
How strong must an electric fence be to repel bears?
Fence Maintenance
Designing and Installing an Electric Fence
Some Existing Electric Bear Exclusions in the Adirondacks
Fence and supply vendors
Portable electric fences for backcountry use
Why use electric fences for deterring bears?
Living in black bear country is exciting enough without having bears attracted into your yard or near your business by food or garbage odors. Attracting bears close to homes and businesses is not only inconvenient when bears cause property damage and unhealthy for the bears, it can also be illegal. The New York State Department of Environmental Conservation (NYS DEC) prohibits the intentional or negligent feeding of bears. Bears that are attracted into communities, or near to residences because of poorly stored food or garbage, are often struck by vehicles while crossing roads and highways. They can cause hundreds of dollars worth of damage to buildings, sheds and other property. The NYS DEC Wildlife staff responds annually to hundreds of bear nuisance complaints in the Adirondack State Park. Region 5 DEC staff in the Adirondacks responded to nearly 300 complaints in 2003 alone.
· Electric fences can effectively deter while not injuring bears
· They can be used to help prevent attraction and habituation of bears
· They are easy to use and maintain when installed properly
· They are an affordable one-time solution when installed properly
Electric fences can be used to protect:
· Trash containers
· Compost bins
· Gardens and fruit orchards
· Bee Hives
· Livestock
· Commercial campgrounds
· Remote camps and cabins
How safe are electric fences?
Although electric fences do deliver an electrical shock that repels animals, they are designed to deliver the jolt very briefly and at a low amperage which is safe, though unpleasant to animals and humans. An electric fence must include a fence charger or energizer made specifically for this purpose. The charger converts regular household current (110 volt alternating current; AC) into direct current (DC). It also sends the charge through the wire in short pulses so that there is not a continuous shock and the animal will have an opportunity to move away. (CAUTION: Never connect an electric fence to an outlet without a fence charger designed for that purpose.)
How do electric fences work?
Electric fences consist of four main components:
1. A power source
2. An electric fence charger
3. Un-insulated wires attached to insulated posts, surrounding the protected area
4. A grounding rod.
The fence charger or energizer converts the power source to high voltage, low amperage charges that are delivered in quick pulses to the fence wires through the positive terminal. The grounding rod is driven into the soil near the fence and is connected by a wire to the negative charger terminal. These components create an open circuit that is closed when an animal touches the wires. The animal gives the current a path to follow into the soil, to the ground rod and back to the charger, delivering a shock. Animals quickly learn to avoid this unpleasant sensation and rarely try to pass the fenced area again. (Most fences also include a gate with insulated handles for entering and exiting the area without turning the fence off.)
The fence charger can be powered by a regular household outlet (110 V) or by batteries and may differ in the strength of the charge that can be delivered, depending on model. Twelve or six volt DC batteries are a good choice when the fence is in a remote area. These "wet cell" batteries can be charged with boat and car engines, portable generators, or solar panels. Nine-volt dry cell batteries can also be used but cannot be recharged. A twelve volt battery can last up to 3 months without a recharge Fence chargers, fence wire, posts, post insulators, batteries and solar panels can generally be purchased at hardware stores, farm supply stores, or feed mills.
Fence wires need to be strong and durable enough to withstand both the local weather conditions and an occasional bump from large animals. Fourteen to seventeen gauge wire is the most common. Heavier wire is more expensive but lasts longer and has less resistance to the flow of the electrical current. Galvanized steel wire or solid aluminum wire are the most common types and both withstand weather well. Aluminum wire is more expensive but will never rust, weighs less and conducts electricity four times better than steel wire.
Fence posts can be made of wood, steel, plastic or fiberglass. They should be strong enough and set into the ground deeply enough so that the fence wires can be pulled tight without tilting or bending them out of shape. Steel posts and most wooden posts require plastic or porcelain insulators to support the wire and prevent accidental grounding of the charge through the post. The fence wire can be attached directly to stout plastic or fiberglass posts and some posts come pre-drilled so the wire can be attached with cotter-pin type clips.
Ground rods are essential to a good fence and should be good conductors and at least 4 feet long and 5/8 inch in diameter. Solid copper or copper-coated steel provides the best ground. Drive the rod at least three feet into the soil if possible. Where soil and weather is especially dry it will help to soak the soil around the ground rod with a few buckets of water. A steel pipe can also be used in dry conditions so that water can be poured down the inside of the pipe. Another grounding trick is to position the ground rod under shed or other building roof eves where possible so that water drains around it, keeping it damp. (The NYS DEC fence diagram materials list includes a plastic trash basket to cover and protect the charger and battery from rain. By setting the trash can at a slight angle and cutting an opening near the rim rainwater will funnel onto the ground rod below the charger.)
Other fence parts:
Several types of gate handles can be purchased to make entering and exiting the fence safer and easier. Most are made of plastic or rubber and have an interior spring to make opening and closing easier while putting tension on the gate when it is closed. Some gates are made of coiled, spring wire that gets the gate out of the way and off the ground when it is open and keeps it tight when it is closed.
It’s a good idea to hang some warning signs on your fence to let passers-by know what the fence is about. Voltage testers are handy for checking the fence wires for the proper charge. They are available from most fence vendors.
How strong must an electric fence be to repel bears?
Professionals who regularly install or use electric fences for bears suggest that a charger should supply 5,000 to 7,000 volts. The power provided by fence chargers is rated in joules and joule ratings between .025 and 0.70 have proven effective for deterring bears. The strength needed will also depend on the length of the fence, the number of wires used and conditions such as weather and vegetation that may be touching the fence. Very damp conditions can drain power as can vegetation brushing against the fence. “Low impedance” chargers are designed to overcome these conditions and you should be sure to specify this when purchasing supplies or hiring someone to build the fence.
How much does an electric fence cost?
Fence costs will vary depending on the size of the area they are designed to protect. Supplies for a well built fence, large enough to protect three small dumpsters (an 18 foot by 34 foot area) will cost about $390.00. This cost includes all hardware, fence signs, etc.
Fence Maintenance
A little preventive maintenance will insure that your fence is working properly when you need it most.
· Always protect the charger and power source from the weather. Water can damage or short circuit both of these components. An inverted plastic trash can used as a cover works well.
· Keep the fence wires under tension. Loose or sloppy wires can allow a bear to slip through a fence. Loose wires will also ground the system out if they come in contact with conductors or the ground. Falling tree branches or careless drivers sometimes bump and stretch the wires.
· Trim vegetation away from the fence. Vegetation can ground the fence out or weaken the charge.
· Keep the gate closed. A gate inadvertently left open for one night or even a few hours may allow that passing bear to walk in.
· Check the fence charge regularly. Some fence chargers have a warning light to let you know of a break in the fence. Even so, it may be a good idea to have a fence voltage tester. These hand-held units are inexpensive and when touched to the wires will give you a voltage reading. The voltage should be maintained at about 5000-8000 volts throughout the fence.
Designing and Installing an Electric Fence
If you decide to have an electric fence installed you may wish to contact a local fence vendor for the job. Take a look at the vendor listings for a supplier in your area. Link to vendor and information list.
Should you decide to construct your own fence, the New York State DEC has provided an example diagram and materials list. This fence design has worked well at several locations in the Adirondacks. Link to DEC PDF file: (ElectricBearExclusionFence). A list of electrified bear exclusion fences currently being used in the Adirondacks is provided below.
In very dry locations, where it is difficult to get a good ground, a fence vendor may suggest alternating positive (hot) wires and negative (ground) wires in the fence. This design works well with combinations of four or eight wires. When a bear attempts to pass between two adjacent wires it completes the circuit between the positive and the ground, receiving a shock. Although bears rarely attempt to jump over a fence as a deer would, the top wire should always be a “hot” wire. This will help prevent entries where the ground is uneven or the wire sags for any reason, giving a bear a place to climb or step over the fence.
Some Existing Electric Bear Exclusions in the Adirondacks
These anti-bear installations were built with the assistance of Region 5 DEC Wildlife staff, at complainant’s expense. None of these installations have been defeated by bears and the bears appear to avoid electrified areas more than they avoid non-electrified physical barriers.
Electric Fence Location
Lyon Mountain Senior Housing Lyon Mountain, Clinton County
Raquette Lake Boy’s Camp Raquette Lake, Hamilton County
Gregg Retten (Temporary) Paul Smiths, Franklin County
Long Lake Town Transfer Station Long Lake, Hamilton County
Dragon City Restaurant Speculator, Hamilton County
Donaldson Campground Saranac Inn, Franklin County
Neighborhood House Senior Housing Keene Valley, Essex County
Electric Fence and Supply Vendors
Gallagher Power Fence Inc.
800-531-5908
www.gallagherusa.com
Provides quality fencing materials and a comprehensive on-line manual on fence design and advice. Visit the website to find a dealer near you and/or for local fence installation information.
Agway
http://www.agway.com/Farm/Farm.htm
Local vendor; sells electric fence supplies. Find a store near you or order on-line.
Aubuchon Hardware
http://www.hardwarestore.com
Local vendor; sells electric fence suppies. Find a store near you or order on-line.
Margo Supplies Ltd.
403-652-1932
info@margosupplies.com
www.margosupplies.com/canadian1/fencing.htm
Mail-order supplier; designs, installs and sells electric fences that have proven effective in deterring bears. Specializes in safe, effective, and humane solutions for dealing with wildlife problems.
Nasco Farm and Ranch Supplies
800-558-9595
http://www.enasco.com
Sells a complete line of electric fence supplies.
Sureguard Fencing
www.sureguard.com.au
Suppies Bear-specific Electric Fence Products
Kencove Farm Fence, Inc.
Phone 800-KENCOVE (800-536-2683)
Electric Fence Manual
http://www.kencove.com/stafix/contents.htm
Backcountry Bear Fences
Understand more about deterrence and conditioning of bears with portable electric fencing.
See a video of one in use:
National Outdoor Leadership School
www.nols.edu/resources/research/movies/bearfence_xl.shtml
Bear Shock
1-800-232-7941
pepperpower@udap.com
www.udap.com/bearshock.htm
Bear Shock is the first ultra lightweight battery-powered, electric fence system.
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