| What is an electric fence and how does it work? |
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A correctly designed and constructed electric fence works by the combination
of a physical barrier and a psychological imprint created in the mind of the
animal. A fencer unit (or energizer, controller) attached to the fence wires
produces a short but painful shock, similar to a sharp whack from a riding
crop, when touched by the horse. Once the horse has touched the fence a few
times he learns where the pain comes from and will stay inside the boundary.
These electric shocks or impulses are painful but harmless and it is essential
to allow the horse to get a few shocks to train him.
Additionally, it is equally important that he always gets a shock when he
touches the fence to maintain his respect for it, so the fencer must be kept on
at all times.
Compared with barbed wire electric fences are much easier to install and
move, lower in cost and will not harm the horse. They can also be used with an
existing old fence to prevent rubbing or, in the case of wooden fences, chewing.
An electric fence is a complete system and care should be taken to ensure
that all components are properly matched for
maximum efficiency.
Electric fence terminology
As already mentioned, the components of an electric fence work as a
complete system but the heart of the installation is the fencer unit. This
produces the current or shock, often referred to as impulses of energy, at
approximately one second intervals along the fence line. The impulse duration
is 3-5 microseconds.
The measure of the energy or strength of the shock is in Joules and one Joule
is one Watt per second.
The size of the fencer is generally stated in stored energy in Joules but it is the
discharge energy which really matters as this is the maximum the fencer can
produce. The higher the Joules produced the greater the shock felt by the
animal and therefore the greater the psychological effect.
Voltage is the measure used to send the energy down the fence line. Contrary
to some popular opinions, voltage does not
hurt. It is simply the pressure which makes the current flow. Voltage = intensity
of current x resistance.
Resistance is measured in ohms = Volts / Amperes. This is the measure of the
restrictions to current flow. A large diameter wire has lower resistance than
small diameter wire so more current will flow for a greater length. Resistance
reduces the current or shock available at the end of the line.
When an animal touches a fence wire, in order to receive a shock a voltage is
needed to "push" the energy through his skin, generally not less than 2000
Volts. The resistance of the animals body through which the current has to
flow is around 2000 Ohms depending on size/weight/species and other
variables. Zero Ohms would be no resistance - a direct short. 50000 Ohms
would be total insulation i.e. No current could penetrate this level of resistance.
Components of an electric fence
• An electric fencer, often referred to as an energizer, produces
regular impulses of current or energy. It can be powered by
batteries, mains or, where appropriate solar.
• Fence wires or conductors carry the current from the fencer
unit along the fence line.
• Insulators are used on metal or wooden posts to carry the
wires and to prevent shorts.
Plastic posts are self insulating and therefore do not need
additional insulators.
• A good earth system is essential to allow the circuit to be
completed when the animal touches the wire thus enabling it to
feel the shock.
How to find the best fencer for your needs?
Selecting the best type of fencer for your individual situation is
very important and therefore we recommend you read these
general guidelines carefully.
Always select a fencer with the maximum energy for your
circumstances by following these guidelines:
• Fencers with an impulse energy of below 0,5 Joules are
suitable for easy to control animals, short fences of several
hundred metres and good conductive wire.
• Fencers with an impulse energy of up to 5 Joules are suitable
for more difficult or thick skinned animals, average vegetation
on the fence, and lengths of a few kilometres with good wire.
• Fencers of greater than 5 Joules capacity are used for long,
permanent fences, typically boundaries (using good quality, high
tensile steel wire) and, with above average vegetation growth.
Practical tips
The first consideration when deciding which fencer to buy is the
availability of power.
Where a 230V power supply is convenient then a mains
powered fencer is the best solution. For a remote area where
the fence is likely to be moved on a regular basis then a 6v or 9V
fencer is the right solution as it contains the battery inside the
carrying case and is therefore fully portable. It is lightweight,
handy and thus most flexible in use. For higher power in remote
areas then a 12V fencer is the best. This would operate from a
12V rechargeable wet battery, which ideally should be a leisure
type of battery which are designed to deep discharge.
Always remember that animals with dense hides or untrained
animals and wild species will require higher powered fencers.
For example, horses, pigs, and pets are easily controlled whilst
sheep, goats poultry and wild rabbits can be more difficult.
• An electric fencer, often referred to as an energizer, produces
regular impulses of current or energy. It can be powered by
batteries, mains or, where appropriate solar.
• Fence wires or conductors carry the current from the fencer
unit along the fence line.
• Insulators are used on metal or wooden posts to carry the
wires and to prevent shorts.
Plastic posts are self insulating and therefore do not need
additional insulators.
• A good earth system is essential to allow the circuit to be
completed when the animal touches the wire thus enabling it to
feel the shock.
How to find the best fencer for your needs?
Selecting the best type of fencer for your individual situation is
very important and therefore we recommend you read these
general guidelines carefully.
Always select a fencer with the maximum energy for your
circumstances by following these guidelines:
• Fencers with an impulse energy of below 0,5 Joules are
suitable for easy to control animals, short fences of several
hundred metres and good conductive wire.
• Fencers with an impulse energy of up to 5 Joules are suitable
for more difficult or thick skinned animals, average vegetation
on the fence, and lengths of a few kilometres with good wire.
• Fencers of greater than 5 Joules capacity are used for long,
permanent fences, typically boundaries (using good quality, high
tensile steel wire) and, with above average vegetation growth.
Practical tips
The first consideration when deciding which fencer to buy is the
availability of power.
Where a 230V power supply is convenient then a mains
powered fencer is the best solution. For a remote area where
the fence is likely to be moved on a regular basis then a 6v or 9V
fencer is the right solution as it contains the battery inside the
carrying case and is therefore fully portable. It is lightweight,
handy and thus most flexible in use. For higher power in remote
areas then a 12V fencer is the best. This would operate from a
12V rechargeable wet battery, which ideally should be a leisure
type of battery which are designed to deep discharge.
Always remember that animals with dense hides or untrained
animals and wild species will require higher powered fencers.
For example, horses, pigs, and pets are easily controlled whilst
sheep, goats poultry and wild rabbits can be more difficult.
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