August 7, 2014 from 12:30 pm to 3:30 pm

Rain or Shine! Dress for the weather!

 Join us for a discussion and tour of:

• Spring Creek Farms and their grazing system
• Stream Buffers
• Other Best Management Practices
• Funding Sources for you and your farm

The event is free but  please RSVP by July 24 to

Christine Esterline 610-372-4657 Ext. 210

or Christine.Esterline@berkscd.com

 

A common concern of all electric fence users is lightning strike and a blown up energizer. Mains
units should be installed with lightning protection on both the incoming power side and the fence
side. For incoming surge protection, a plug-in surge protector should be installed at the power outlet
and the energizer plugged into the surge protector. This is the same type of protector as used on
home computers and other valuable appliances and can be picked up at almost any appliance or
variety store. Most rural electric systems experience daily variations in voltage flow that are as
hazardous to electric fence energizers as lightning strikes and so a surge protector is good insurance
for everyday usage.
For lightning protection on the fence side, several practices are advisable. Location of the energizer
is the first step. Place the energizer in a building in a low-lying area or a lightning rod protected
building. Avoid placing it in a building on a hilltop with no lightning rods. Frequently there is no
choice where the energizer is to be installed, but when there is a choice use common sense and stay
away from lightning prone areas.
The ground stakes should be well away from the ground system of power poles or the service box.
Never use the existing ground system of power poles or breaker boxes for the energizer ground. A
short in the power line can feed into the fence system through the common ground and create a
dangerously charged situation in the fence as well as damage the energizer. A lightning strike on a
power line with a common ground with the energizer creates a situation where the energizer could
be damaged through both the incoming line and the ground system. The ground system for the
energizer should be placed at least 25 feet from the nearest power line ground rod.

An induction coil or lightning choke should
be installed in the fence lead-out wire near
the energizer. The induction coil is made by
coiling 6 to 8 loops of heavily insulated 12
gauge wire in an 8 to 10 inch diameter circle
and taping the loops together. A lightning
choke is made from a loose coil of hi-tensile
wire with 8 to 12 loops spaced about 2
inches apart on a mounting board. Either
device acts as a lightning brake by forcing
the high voltage lightning surge into a
circular flow and creating a resistance field
by which the flow of lightning energy is
reversed. The energy flow goes back up the
fence and away from the energizer. The
induction coil is much easier to assemble and
is our preference. Once we started using
induction coils in our installations we
virtually eliminated all damage to energizers
due to lightning strikes.
A lightning diverter should be installed where the
lead-out wire attaches to the fence. A lightning
diverter at this location serves the double purpose
of diverting some of the initial energy surge to
ground and serving as a route of exit from the fence
of the energy flow reversed by the induction coil.
This device has two terminals for attaching wires
and leads from each terminal that are set with a
wide enough gap to prevent the normal energizer
voltage flow from arcing across, but close enough
to allow a lightning voltage spike to jump easily
across and pass to ground. The top terminal is
attached to the uppermost electrified wire and the
lower terminal to a ground rod. The lightning
diverter ground must be separate from the energizer
ground. If a common ground rod is used, the
lightning spike can pass through the common
ground system and return to the energizer
potentially damaging the circuitry. It is relatively
cheap insurance to install several lightning diverters
through the fence system at lightning prone
locations and where fences network together.
Ideally, more total ground rod capacity should be installed under the lightning diverter system than
under the energizer itself. Several types of lightning diverters are available, but all work on the same
principle.

Just as the energizer should be matched to the size of the
fencing job, the solar panel must match the energy draw
of the energizer. For each 1 joule energizer output, allow
seven watts of solar panel capacity in high sunlight areas
and ten watts in low sunshine areas. In Missouri the
seven watt capacity has proven adequate in most
conditions, but in wet cloudy springs seven watts has
proven inadequate for keeping batteries fully charged.
Solar panels should be oriented from due south to no
more than 20 degrees to the southwest. The logic for
orienting the panel slightly to the southwest is because
mornings are often cloudy with clearing in later
afternoon, particularly in the spring and fall when day
length is shorter, thus more hours of intense radiation
occur when the sun has already progressed to the western
portion of the sky. The panel should be oriented so many
degrees off horizontal based on your latitude. Because
the angle of the sun's rays striking the earth differs
through the seasons, the efficiency of a fixed orientation
varies seasonally. For panels used only during the spring
to fall grazing season, 25-30 degrees off horizontal may be appropriate. Winter grazing requires a
panel more steeply inclined, up to 60 degrees off horizontal with a south to southwest orientation.

The particular model of energizer to choose depends on the total distance of fence to be charged.
Manufacturer's claims on this point can be very confusing. If the energizer has a joule rating assigned
to it, it should be simple to determine how many joules of power are needed for your situation.
However it is not so simple. One major fence company makes energizer recommendations based on
the premise of ½ mile of fence per joule of energizer capacity. Another manufacturer suggests up
to 10 miles of fence per joule of energizer capacity. The first company is presenting a worst-case user
scenario while the other is presenting a best-case scenario. Our experience has been that allowing
one mile of fence per joule output will give satisfactory performance in most situations.
The type and construction of the fence affects the total mileage capacity of the energizer. Single wire
paddock subdivision fences for cattle are generally well up out of the vegetation and, if well
constructed from high quality material, several miles of this type fence can be electrified for every
joule of energizer output. Multi-strand perimeter fences and three strand sheep paddock fences may
carry very heavy vegetation load on the lower wires and much less total distance will be served by
the same energizer as used in the single wire situation.

The next decision to make is whether to use a battery unit or mains unit. This choice depends mainly
on availability of 110v or 220v power source. In almost all situations where power is available, it
is advisable to use a mains unit. Mains units are invariably cheaper per unit of output power than
battery units. Worries about keeping batteries charged up and the fence hot are eliminated by mains
power. Monthly electricity cost for operating mains units, based on $.08/kWh, range from less than
$.05/month for small units to around $1.50/month on very high-powered units. Even if a mile of
feeder wire is required to bring power from a building housing the mains unit to the actual pasture,
it will generally be cheaper in the long run to do this rather than use a battery unit with solar
recharging of a battery. Available mains power units run from less than 1 joule output to 20+ joule
output.
If mains power is not available and a battery unit is required, there are many sizes and types to
choose from. Self-contained lantern batteries, either 6 or 9-volt cells or a multiple of ‘D’ cells, may
power very small units with less than 1 joule output. New technology in dry-cell and gel-cell
batteries has increased the time period which battery units can be operated between recharges or
replacement. Gel-cell batteries are generally designed to be recharged but require special chargers
to maintain battery life. A new generation of long-life, disposable dry-cell batteries offers potential
for more than six months battery life. For remote units that are not visited on a regular basis, these
long life battery systems offer greater management opportunity than has previously existed without
use of solar recharge systems. Current technology in “smart” energizers allows for even greater
battery life. Smart energizers detect the load upon the fence and adjust pulse output to the demand.
If load is minimal, the battery draw is reduced and battery life is prolonged.
Larger wet-cell units up to over 20 joule output can be powered by 12v automotive type or deep
cycle gel batteries. When using 12v systems, it is highly advisable to install a solar panel to keep the
battery charged. The higher the output of the energizer, the more rapidly a storage battery is drained.
The largest wet-cell battery units may fully drain a deep cycle 12v battery in less than a week. To
avoid the weekly turnaround of batteries, a solar recharge system is a must.
There are also energizers available that can be used either as 12v battery or 110v mains units. These
units offer a great deal of versatility in use. Some graziers are concerned about controlling animals
if the power goes off for an extended period due to weather events such as hurricanes and ice storms.
The dual power units offer the opportunity to switch to battery power if the mains power is out for
more than a few hours. They can also travel from the home base of operations to a remote grazing
location to be used with battery. These units can work well for custom graziers operating on leased
land.
Some people have the perception that battery units are inherently less powerful than mains units.
When comparing units with the same output joule rating, the capacity to energize a given length of
fence are the same, as long as the battery is fully charged. It is only when the battery has been
partially drained that battery units can be considerably weaker than their mains counterparts. Using
a solar or wind recharge system can eliminate the weak battery failure.

Modern electric fence energizers have the capacity to maintain effective voltage for animal control
under much more adverse vegetative load conditions than earlier types. Low-impedance is the term
most commonly used to describe the modern energizer. Low-impedance energizers are characterized
by moderate voltage and a very short pulse length. Manufacturers have attempted to rate the power
capacity of fence energizers by several methods including miles of fence powered, farm acreage
covered, voltage output, effective voltage under varying resistance levels, and joules of energy.
Each of these ratings has its limitations.
Miles of fence powered is meaningless unless
the wire gauge, vegetation load, quality of
fence construction, and other factors are
specifically indicated. Size of the farm means
nothing without some idea of the level of
paddock subdivision on the farm. Voltage
output is generally peak voltage potential
with no fence attached to the energizer or
"no-load" voltage, as it is commonly referred
to. An energizer with 15,000 v no-load
potential may actually be considerably less
powerful than a unit with 5000 v no-load.
Joules are the most common means of comparing fence energizers. One joule is equal to an electrical
output of 1 watt per second. Comparison by joule output is only valid if the pulse lengths are similar
and if measured at comparable resistance levels. Most manufacturers rate their units based on output
energy. This is the amount of energy the unit consistently pulses into the wire. A few companies use
stored joules to rate their units. Stored joule measurements are usually 20-30% greater than output 

2 joules so units cannot necessarily be directly compared across manufacturers. For example, a 10-
joule stored energy output energizer is equivalent to a 7 to 8 joule output energy-rated unit.
Very often the energizer model number itself tells what the energizer capacity is in joules. The two
units shown below are examples where the ‘M’ indicates they are mains (110v plug-in) units and the
numeral specifies the output joule rating. The M1000 has 8 times the output power of the M150. This
does not mean it produces a higher voltage on the fence line, only that it will maintain the power
level on six times as much fence.
With these points in mind, how does one go about selecting the proper energizer for a particular
situation? You need to consider how many miles of fence will you have, will it be single or multiwire,
what is the expected vegetative load on the fence, what type of livestock or wildlife are you
attempting to deter, and what is available as a power source.

Selecting and installing the most appropriate fencing system for your grazing operation is a key step
toward successful pasture-based livestock production. Three types of fencing are likely to be used
in a grazing cell: perimeter, permanent subdivision, and temporary or portable subdivision fencing.
Electrified 12.5 gauge hi-tensile wire makes most satisfactory perimeter fence and permanent
paddock fencing. Numerous options are available for portable fencing. This guide deals with
material selection and proper installation of all types of electrified fences for grazing systems.
Materials are covered in individual sections.

Electric fences are an important tool for protecting livestock in Alberta. Such fences have been used in the province to protect livestock from predators for more than two decades. 

Predators such as coyotes, wolves, bears and domestic dogs are shocked when they try to penetrate an electric fence. For the most part, electric fences have been used to protect pastured sheep; however, these fences do have other applications. They can be used around birthing yards to protect newborn calves or lambs, or they can serve to protect poultry and farmed deer. 

A study in the mid 1970s showed a 90 per cent reduction in sheep predation losses on farms with electrified pasture fences. This evaluation of electric fences to protect sheep from coyote predation was conducted by Alberta Agriculture, Food and Rural Development. Other studies have confirmed the effectiveness of electric fences to prevent sheep predation. 

Electric fences are easily adapted to most livestock operations. These fences are relatively easy to maintain and are economical to build. However, electric fences require routine inspection and maintenance to ensure proper operation and protection capability. Also, snow and frozen ground in winter can greatly reduce the effectiveness of electric fences for predation control. 

Electric Fence Designs

An effective electric fence for predator control can be constructed with either a multiple of single strand wires or a combination of wire mesh and single strand wires. A mesh-wire fence is more expensive to build than a fence made from single strand wire. However, an electrified mesh-wire fence presents a greater physical barrier to predators and requires less maintenance and fewer electrified wires than a fence using only single-strand wires. 

Nine-wire fence
An electric fence made with 9 single strands of 12.5 gauge, high-tensile smooth wire and spaced as shown in Figure 1 provides an effective barrier to predators. The overall height of this fence design is 1.37 m. Wires are alternating, charged (+) and grounded (-), beginning with the bottom wire as a charged wire. The top wire should be charged when cattle or horses are either enclosed or share a fence to prevent them from damaging the upper portions of the fence. 


Figure 1. Nine-wire fence, viewed from inside of the fence .

Mesh-wire fence
Galvanized, high-tensile mesh wire should be used for predator control. This wire is more versatile and longer-lasting and can be stretched tighter than standard farm mesh wire. The high-tensile mesh wire is reasonably priced and available from fencing suppliers in various heights. Galvanized mesh at least 1.2 m high with predator-proof spacings (smaller spacings on the bottom section of the mesh than at the top section) is recommended. 

To build a new fence, place the mesh wire on the inside of the pasture posts. Pull the mesh taut, position the bottom of the mesh tight to the ground and staple the mesh securely to the posts. The fence wire must be tight to the ground to reduce the chances of a coyote digging under. 

If a fence is not taut, the wires will sag and make a space easier for coyotes to penetrate. Single strand, 12.5 gauge high-tensile wires can be placed 15 cm or less apart above the mesh to increase the height of the fence to 137 cm or more. Figure 2 shows the recommended mesh-wire fence configuration, which is also electrified. 


Figure 2. An electrified, high tensile mesh-wire fence, viewed from outside the enclosure .

An existing sheep fence made from mesh and barbed wire can be electrified. The fence must be in good condition, and the wire must be free of rust, undamaged and taut. The spacing in the mesh wire must be no larger than 15 cm by 15 cm. Coyotes, foxes and small domestic dogs may crawl through spaces larger than 15 cm. Fence posts must be sturdy and preferably tall enough to make the fence at least 137 cm tall. If the posts are not tall enough to support the top wires, add extensions to increase post height to at least 137 cm. 

Considering the requirements for an effective electric fence for predator control, it is often impractical to modify an existing mesh-wire sheep fence. 

Predators can penetrate a fence by digging under, jumping between the wires, crawling through holes in the mesh or jumping over the top of the fence. To stop predators from digging under the fence, place a charged 12.5 gauge high-tensile wire 10 - 15 cm above ground level and 10 - 20 cm out from the mesh. 

If the fence posts are 10 cm or more in diameter and the mesh is attached to the inside of the posts, insulators and the charged wire can be attached directly to the outside of the posts. If the fence posts are less than 10 cm in diameter or the mesh is on the outside of the posts, offset brackets will be needed. Brackets can be built or purchased. 

Damaged mesh or mesh with openings larger than 15 cm by 15 cm may allow coyotes, foxes and small domestic dogs to crawl through the fence. Repair or replace damaged mesh. Add one or more strands of high-tensile smooth wire, spaced 15 cm apart, above the mesh to increase the total height of the fence to at least 137 cm. This is the minimum height needed to prevent coyotes from jumping the fence. Make sure the mesh and single wires are taut. If horses or cattle are enclosed by the fence, electrify the top wire to keep them from pushing on the wires. 

How An Electric Fence Works

For electricity to flow in a system such as an electric fence, there must be a complete and uninterrupted (closed) circuit. The electrical current must travel from its source (fence energizer) through the circuit (fence) and back to the source. This flow only occurs when a charged wire of the fence becomes grounded. 

Under normal operating conditions, an electric fence functions as an incomplete (open) circuit with repeating pulses of electricity generated by the energizer sent through the charged wires of the fence. When an animal touches a charged wire, it grounds the fence, creating a closed circuit. An electrical pulse travels through the animal and back to the energizer, delivering a shock to the animal. 

Other objects and materials including vegetation, sticks, fallen trees and non-insulated posts in contact with charged wires can also create a partial or total closed circuit. This partial or closed circuit can result in a reduced electrical charge (voltage) and an inadequate shock to repel predators that contact charged wires of the fence. Fences should be checked and maintained regularly to address this potential problem. 

A shock from an electric fence that uses charged and grounded wires can be delivered in either of the following ways; see Figure 3:

• A predator receives the maximum shock when it touches a charged wire and a grounded wire at the same time. Electricity in the charged wire travels through the predator into the grounded wire and back to the energizer. 
  
  The conductivity (how easily electricity flows through a circuit) is very high. This conductivity forms the basis for recommending that all non-charged wires on an electric fence be attached to the ground rods of the energizer.
• When a predator touches a charged wire only, electricity travels through it into the soil, through the soil to the nearest ground rod and attached grounded wires to the energizer. Conductivity through soil, depending on soil type and moisture, is poor compared to wire. Therefore, the shock a predator receives in this way can be much less intense than that received from contacting both a charged and grounded wire at the same time.

The closer a predator is to a ground rod when shocked, the more intense the shock will be. It is therefore very important to ground non-charged wires to ground rods at regular intervals of the fence. 


Figure 3. The ways current can flow when a predator touches an electric wire.

Fence Line Selection and Preparation

Careful planning and proper fence line preparation are important first steps in the construction of an effective fence for predator control. 

Select the most level ground to run the fence. Do not cross creeks, sloughs, ravines or other unstable and difficult areas if at all possible. Keep the fence line as straight as possible. Clear trees, shrubs and debris from the fence line. Make the fence line wide enough both to prevent trees from falling on the fence and to permit a vehicle to be driven beside it for fence construction, inspection and maintenance. 

Coyotes usually penetrate mesh or nine-wire fences by digging or crawling under the bottom wire. So, it is extremely important to level the fence line properly. The fence line must be even enough to run a charged wire within 7.5 to 10 cm of the ground. The distance from the bottom wire to ground level may vary a good deal if fence lines are not levelled. An uneven fence line may permit coyotes to get under the wire. If the charged wire touches the soil, the voltage may be inadequate to keep coyotes out. 

After completion of the fence, the fence line should be re-seeded to grass to prevent erosion and weed growth. Select a low-growing grass species that will minimize the risk of vegetation grounding the bottom charged wire. Common broad-leaved weeds that cause grounding problems can be controlled with herbicides. 

In 1938, the first electric fence was developed in New Zealand by Gallagher. Since that time, electric fencing systems have made farm and ranch life easier. Today, both permanent and portable electric fencing products are used all over the world.

Basics of Electric Fencing

Electric fencing is ideal for grazing or pasture management by containing animals on a selected area of pasture or crop. It also may be used to protect gardens and landscapes from animal damage.

Permanent electric fencing is economical, easy to install and easy to maintain. Temporary electric fencing is an effective temporary barrier for short-term animal control and rotational grazing.

Electric Fencing is...

• Safe: Animals remember the short, sharp but safe shock and develop respect for the fence.
• Easy to install: An electric fence takes less than half the time to build compared to traditional fence systems.
• Durable: A non-electrified fence experiences constant wear and tear under stock pressure. Because your animals learn to avoid an electrified fence, your fence will last longer and remain in good condition.
• Economical: Electric fences cost less than 50% of traditional non-electric fences.

How does an Electric Fence work?

Electric current (AMPS) only flows when a circuit is completed between a positive and negative 
terminal.

 

 

In this diagram the current cannot flow from the positive terminal to the negative terminal because the switch is open.

 

 

 

In this second diagram, the switch is now closed, allowing the current to flow from the positive terminal through the light bulb (lighting the bulb) to the negative terminal.

 

 

An electric fence circuit is made on a larger scale. The energizer fence terminal (positive) is connected to the insulated fence wires, and the energizer earth terminal (negative) is connected to galvanized metal stakes driven into the ground.

The same 'circuit completion' (as in the second diagram) is necessary before the animal gets a shock. An animal standing on the ground and touching the electrified wires will complete the circuit like the closed switch in the second diagram above.

 

For example, a bird sitting on the wire will not receive a shock. It is not touching the ground so the circuit is not completed.  A person wearing insulated footwear will only receive a small shock because all the current cannot pass through the insulated soles.

Dry, sandy or pumice soil is a poor conductor of electric current, so it is a good idea to add an ground (negative) wire into the fence. The animal must touch both a hot wire and ground wire to feel an effective shock.

 

Choosing the Right Energizer/Fence Charger

Once you have decided what type of electric fence you want for your property, you will need an energizer also known as a fence charger to power it.  The correct energizer size for your property is determined by the type of animal to be fenced, distance of fence to be powered and the number of wires in the fence.

There are two types of energizers:

• Mains powered - these are energizer units which are plugged into a mains power supply.
• Battery/Solar powered - these are energizer units which can be left out in your paddock and require a battery to run them. Two batteries can be rotated on a regular basis or a solar panel can be an effective means of continuously charging your battery.

Steps to Good Grounding

Grounding (a.k.a. earthing) is perhaps the most neglected component of many fence systems. We recommend three ground rods, 6’ deep and spaced 10’ apart are the minimum recommendation. Never attach copper to steel. Electrolysis can occur and result in corrosion which weakens shocking power. Use galvanized ground wire and grounding rods to avoid this problem.

Consider that most energizers use galvanized or stainless steel terminals – not copper. Think of your ground system as an antenna that gathers electricity in order to deliver the shock to the animal. Modern satellite receivers can tune in to more television channels than the “rabbit ear” antennas of the past. A hose clamp holding a piece of copper wire to a rusty t-post has been the weakest link of many electric fence systems.

- See more at: http://www.gallagherusa.com/electric-fencing/electricfence101.aspx#sthash.znQ0H6eX.dpuf

By Kathy Voth  /   June 23, 2014  /   6 Comments

- See more at: http://onpasture.com/2014/06/23/flerds-sheep-and-cattle-grazing-together-for-pasture-management-and-predator-protection/#sthash.FVz15l3I.ojqkDiqo.dpuf