The Art of Electric Garden Fences

Electric fences for most pastures are an expensive but
mandatory piece of overhead, and no rancher or farmer with
cattle can do without them. Their styles and methods of
operation are many (see “Build a High-Tension Fence“)
but they are designed to enclose areas on a
grand scale. For those of us with smaller but equally
precious garden plots to protect, modified electric garden fences
can assure that your hard-won autumn harvest goes
unmolested by other hungry creatures and that your wallet
will survive the effort.

With lightweight electric fences, you don’t need heavy
posts or specialized tools. All you do is push the
self-insulating plastic or fiberglass posts into the ground
by hand or tap them in with a mallet. And you won’t need
posts at all if you put up an “invisible” radio fence to
keep your doggy out of the veggie patch. But more on that
in a moment.

Visible electrified garden fencing comes in three options:
twine, tape, and net. A ll three are made from strands of
polyethylene combined with metal filaments, the
polyethylene for strength, the metal filaments to conduct
electric current. Would-be marauders coming into contact
with the fence get a jolt that’s not unlike a sharp static
spark.

The beauty of electroplastic fencing is that it goes up
fast. You can fence the average family-sized garden in an
hour or less. After the autumn harvest, you can take the
fence down, roll it up, and put it away for the winter,
giving you an unobstructed view of the backyard while your
garden is fallow.

Polywire Fencing

The basic stuff electroplastic fencing is made of is
electroplastic twine, also known as “polywire.” Lightweight
and easy to cut with scissors, polywire is used much the
same way you would use any fence wire.

It looks a bit different, however, mainly because it comes
in colors–yellow, white, orange, and black. Color
affects both the fence’s visibility and its resistance to
ultraviolet sunlight. Black has the greatest resistance to
sunlight but is hardest to see. Color visibility is
strictly for the benefit and safety of humans, since most
animals are color blind.

Besides enhancing visibility, the different colors are
handy if you put up a wire-return fence, in which some of
the wires are hot while others are grounded. In a standard
electric fence, all the wires are hot. When a would-be
veggie muncher touches the fence, a jolt passes through its
body, into the ground, through the soil to the fence’s
source of energy, and back through the hot wire to complete
the circuit. Dry soil is not very conductive, so an all-hot
system doesn’t work particularly well in dry climates.

With a wire-return system, a marauder touching two lines in
the fence–one hot and one grounded–gets the
message no matter how dry the soil might be. Making hot
wires one color and grounded wires another lets you easily
spot the occasional short-circuit caused when a sagging or
broken hot wire comes into contact with the soil or a
grounded wire.

For a polywire fence, you’ll need lightweight posts every
25 feet along the fence line. Fiberglass or plastic posts
are self-insulating. To hold the wire in place, some
require additional spring clips (looking like convoluted
paper clips; other posts have wire spacers molded right on
them. If you use rebar posts (concrete reinforcement bars,
cut to length), you’ll need to use the more expensive
screw-on plastic insulators.

A reel will keep the polywire from getting tangled or
knotted when you set up your fence and take it down. Reels
come in varying sizes (to accommodate different wire
lengths) and in various styles. Some reels have a ratchet
brake so the spool will stop turning when you stop pulling
the wire. Some have a lock so the wire can’t unwind on its
own. A good reel has a carrying handle, adjustable drag so
the wire won’t run away from you, and a crank for
rewinding. If you like expensive gadgets, you might get a
reel with a battery-powered energizer hidden in the hub. If
you’re on a tight budget, a simple reel designed for
storing extension cords works just fine.

You won’t need a gate if your fence is designed to keep out
small critters–simply step over. For a taller fence
that bars deer or elk, tie each line wire to an insulated
gate handle and hook the handle into a loop in the
corresponding wire at the other side of the gateway. To get
through the gate, unhook the top few wires and step over
the bottom ones. To push a wheelbarrow or cart through,
unhook all the wires. If you use a wire-return system, take
care when you close the gate not to hook a grounded handle
to a hot loop or you’ll short out your fence.

A single strand of polywire is often enough to keep out
small varmints. For rabbits and groundhogs, run it 3 to 4
inches off the ground. For small dogs, try 10 or 12 inches
high. If raccoons are getting into your corn, string two
strands, the first 5 inches up, the second 11 inches from
the first (5-11). An all-purpose three wire fence, spaced
4-5-6, should keep out most small dogs, rabbits, raccoons,
groundhogs, and cats. If salad seekers still slip through,
try a 3-4-6-8 configuration.

Polywire fencing is so easy to adjust, you shouldn’t have
any trouble finding just the right spacing for your terrain
and combination of critters. As a general guideline, for
each species you wish to exclude, string one hot line at
the height of the animal’s nose when it’s ambling along.

Storing away an unused electroplastic fence has a practical
as well as an aesthetic side–a stored fence is
protected from the ravages of sun, wind, and icy weather
and your fence will enjoy a longer useful life if you take
it down seasonally. In doing so, take care not to drag it
along the ground or snag it on rocks. Wrap the fence in
plastic, tape the bundle tight, and hang it where gnawing
rodents can’t get at it. A well-treated elecfroplastic
fence can last as long as 10 years.

Hot Tape

Electroplastic tape or hot tape was invented to overcome
the visibility problems of electroplastic twine. Because of
its width, hot tape is more easily seen by fast moving
animals like deer and by klutzy gardeners who tend to bump
into a fence while planting or hoeing.

Hot tape is made of the same polyethylene strands and metal
filaments as electroplastic twine, only woven into a flat
strip that looks like ribbon. Tape comes in a variety of
colors and in two widths: 1/2 inch and 1 1/2 inch. The
wider version is easier to see, can be stretched tighter,
lasts longer, has better conductivity and comes in a
dual-track version with a built-in wirereturn system.

The visibility of hot tape is enhanced not only by its
width but by its ability to flutter in the slightest
breeze. Fluttering both makes the tape appear wider than it
is and interferes with depth perception, causing marauders
to steer clear. Flutter has its downside, though: wind
abrasion causes tape to wear out more quickly than twine.

Polytape is also not quite as easy to splice as polywire.
Two lengths of twine can be joined with tight knots, but
knots in tape have air gaps that cause the fence to lose
conductivity. Steel buckles are available to improve the
conductivity of splices, but you can accomplish the same
thing for less money with strips of aluminum foil. Start a
square knot, lay a strip of foil against it, wrap the foil
around the tape three or four times, finish tying the knot
and squeeze the splice tight.

You can add a single strand of hot tape to a twine fence to
make it easier to see, or use hot tape alone. For some
critters, you can get by stringing a single tape at nose
height. For most deer that’s 3 feet or a little less, for
elk it’s about 4 feet. To discourage honey-loving bears
from raiding beehives kept for garden pollination, try two
strands of tape spaced 8-12. If that doesn’t do it, go to
three, spaced 10-10-10.

Marauders getting a jolt while investigating a fence out of
curiosity are less likely to come back than animals that
accidentally get zapped. To attract curious deer, smear
heavy foil strips with peanut butter and drape them along
the fence. To attract inquisitive ursines, tie strips of
fresh bacon at intervals along the fence. These treats
entice curious creatures to touch the fence with a moist
nose or tongue, with memorable consequences. A cleared
buffer strip around your garden makes hot tape easier to
see from a distance, giving deer and bear plenty of time to
develop cautious curiosity.

Electroplastic Net

An electroplastic net fence is easier to see and therefore
more reliable than a twine or tape fence. The net is woven
from polywire and comes completely preassembled with posts
and connector clips. One length covers 150 feet and comes
in a neat bundle weighing about 10 pounds.

To support the corners, guy lines with tent pegs are
included. But since guys are easy to trip over and hard to
mow around, you’ll be better off reinforcing each corner
with an extra post driven 18 inches deep. If your soil is
loose or sandy, add a few extra posts along the sides, as
well, so your fence won’t topple when a breeze blows
branches or tumble weeds against it.

You won’t need a gate here, either. You can step over a
short net fence. If you opt for a taller version, just
switch off the juice and roll back the last panel when you
want to go through.

Electroplastic netting comes in a variety of brands and
heights. The shorter the fence, the smaller the mesh and
the more readily it controls small animals. The shortest
net, 20 plus inches, is the standard garden version for
keeping out rabbits, raccoons, groundhogs, and small dogs.
To control deer as well as little critters, run a strand or
two of hot tape above the net.

A standard net fence has all hot horizontal except the
bottom one, which lies along the ground and is therefore
grounded. For use in dry climates, a wire return version
has alternating hot and grounded horizontals. A system with
hot wires of one color and grounded wires of another color
is more sensible than a single color system, because you’re
less likely to inadvertently join a hot line with a
grounded line and short out your fence.

Even though it looks much like a lightweight woven wire
fence, electroplastic netting works only when it’s
energized. Otherwise, rabbits may chew through it and pets
or wildlife will get tangled in it, tearing the net and
possibly getting strangled in the process.

Energy Controlers

To energize your fence you’ll need an electric-fence
controller, which converts electricity into a series of
high-voltage pulses that course through the fence in short
bursts. This is no place to cut corners by trying to make
your own energizer–homemade fence controllers are,
more often than not, lethal. Besides converting electricity
to a less devastating form, manufactured energizers output
a pulse that gives man or beast an opportunity to pull away
during the off time. To keep electroplastic-fence
material from melting, look for a low impedance unit with
an on time of no more than .003 seconds.

Energizers come in various sizes as determined by the
amount of energy they put out. The amount of energy you
need depends on the length of your fence and the number of
line wires it contains. A small unit, putting out around
7,000 volts or up to 0.5 joules, is sufficient for the
average family-sized garden.

Energizers are classified according to their source of
power. The two basic options are plug-in and battery
operated. A plug-in unit makes sense only if your garden is
close to an electrical outlet, say in a potting shed or at
the corner of your house. It is not suitable for a location
where you must run an extension cord from the energizer to
the source of power. The big advantage to a plug-in is that
it more easily overcomes encroaching grass and weeds than a
battery-powered unit. Its chief disadvantage is that it
doesn’t work during power outages–a serious
consideration in most rural areas.

If your garden doesn’t conveniently let you use a plug-in,
a battery-powered controller is your best bet. To keep the
battery from draining quickly, battery-powered units don’t
pack the same wallop as plugins and they can’t handle much
of a weed load. You therefore have to be more diligent
about keeping down grass and weeds along the fence line.

The average garden requires nothing more than a 6-volt
battery controller. When the battery runs down, replace it
with another from any discount store. To keep your battery
running longer, hook it up to a solar collector, or opt for
a controller with a built-in solar panel.

Solar energizers in general tend to be at the weaker end of
the battery-power scale. Some solar energizers are much
better than others, primarily because they have larger
panels. The amount of power collected by the panel must
balance the power used by the energizer, which in turn is
determined by the style of fence you choose. No solar
energizer works well in a shady or perpetually cloudy area.

No matter what kind of energizer you get, it will need some
degree of protection from weather. Some battery-powered
controllers and all solar charged units have built-in
weather protection, but still must be inspected after hail
or moderate winds.

All energizers also need a grounding system. Here again,
some battery-powered units have built-in ground rods; for
others you must purchase a grounding rod and clamp from an
electrical-supply outlet. Do not ground your fence to the
ground wire of a utility pole or to your home’s plumbing
system–it’s a violation of code. Proper grounding
will not only improve the performance of your fence, but it
will minimize the chance you’ll pick up the fence’s
“tick-tick-tick” over your phone or radio. During dry
weather, you can improve the ground by watering your ground
rod when you water your garden.

Invisible Fence

An invisible fence shocks a would-be garden intruder with a
sharp snap that’s similar to that from an electric fence,
but in this case the intruder must be wearing a shock
collar. Known also as “hidden” or “radio” fence, the system
consists of three basic parts: boundary wire that defines
the area to be fenced, a radio transmitter that sends a
pulsed signal through the wire (generated by either a
12-volt battery or a standard 110-volt wall outlet,
depending on the brand), and a battery-powered shock collar
that picks up the signal.

The boundary wire is laid along the ground or buried just
beneath it, leaving your yard unobstructed by cross
fencing. Unless your yard has a sturdy perimeter fence,
stray dogs and wandering wildlife can still get in. The
primary use of this fence is to control your own dog within
your own property.

The dog wearing the collar hears a warning signal when it
enters the radio field, which in this case defines the edge
of the garden area. If the dog doesn’t retreat within
seconds, it gets a shock. After one or two shocks, the dog
learns to back off as soon as it hears the warning.

Fence Prices

Fence prices vary considerably with the style and brand you
choose. To enclose a 75 x 75 foot garden, expect to pay
just under $150 for an eledroplastic-twine or tape system,
complete with 12 posts and a 6-volt battery-operated
self-grounding controller designated for outdoor use. A
20-inch electroplastic net fence for the same-sized garden,
powered by the same energizer, runs about $275. If you want
to control poochie with a radio fence, pay about $100 or
keep shopping.