ELECTRIC FENCE CONSIDERATIONS

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So your new to electric fencing and planning a electric fence design?
10 basic considerations for planning an electric fence.

Spending the time to understand the principles of electric fencing so you can plan your electric fence to suit your desired purpose can save you time, money and alot of frustration.
Being able to select the right electric fence products, for example a solar electric fence energiser over a mains or battery powered energiser can help you to have your fence work for you, not the other way around.  
For the uninitiated planning an electric fence can be a daunting task due to a lack of understanding of the basic principles of how an electric fence operates and what each electric fence component does.

Firstly what is an electric fence?


This from Australia's Sureguard Electric fence Co.

A device called an energizer generates high voltage impulses between its two output terminals. The impulse is very brief and is repeated every 1 to 2 seconds. The fence design is intended to connect the animal to these two output terminals through these fencing wires. When the electrical impulse passes through a muscle in the animal it stimulates the muscle to contract. If you haven't felt an electric fence before, the best description of the feel is like leg cramp but lasting for just a brief moment. By necessity it is very unpleasant so that it provides an effective deterrent when the animal next encounters the fence. The animal remembers the unpleasant experience and avoids touching the wires again. It is NOT injury or damage that produces the discomfort but rather the induced muscle contraction that is unpleasant.

In Summary:

The animal must be simultaneously connected to the both output terminals of the energizer via the fence wires.
Animals with thicker insulating covering need higher voltages.
The applied voltage must pass through muscles. It is the muscle contraction that is unpleasant.

Unlike humans, most animals are well covered with an electrically insulating surface such as fur, hide, feathers, etc. So, whereas humans can make skin contact and get a shock with a voltage as low as 100 volts, most animals require a higher voltage in order to feel anything. High voltages produce long distance sparks that will jump the air gap over the animal's insulating surface. The higher the voltage the longer the spark. Typical spark lengths are 1mm (0.04") for every 2000 volts.

If you're using a Sureguard energizer this voltage could be as high as 9500 volts which should be able to spark nearly 5mm (0.2"). Importantly, if the electrical impulse does not spark across this gap to the animal's skin then the animal feels NOTHING! Therefore, a higher fence voltage can mean increased reliability or effectiveness for well insulated animals.

It's also important to realize that more voltage does not always mean more discomfort. Perhaps you've experienced a spark from common static electricity? Did you know that such sparks can have voltages of 10, 20 or 30,000 volts! Yet the sensation is generally just a slight pin-prick feel. What's happening here? The nerves on the skin are being stimulated as the electrical discharge dissipates over the surface of the skin. This feels a little unpleasant but nothing like a properly induced muscle contraction from an electric fence. To induce a muscle contraction, you must have a voltage difference across the ends of the muscle. In other words, the electrical impulse has to go through the animal. It also has to go through the animal in such a way that stimulates many muscles in order to make the overall "feel" unpleasant enough.

How can the muscle contraction be made strong so that it provides an effective deterrent? Firstly, the electric fence energizer must be able to generate sufficient electrical energy (energy is measured in joules). Most electric fence energizers will do this. However, this energy must be delivered to the animal with minimal loss between the energizer and the animal.

This from Australian Daken Electric Fencing Manual

ELECTRIC FENCING is an alternative method of fencing which offers you
the following benefits:

1. LOW COST


An electric fence can perform the same task as a conventional fence using much less material.

2. EASY TO BUILD


Lower wire strains and generally lighter construction make much quicker and easier construction, especially in difficult terrain.

3. EXTENDED LIFE


Electric fences are not subjected to the same physical pressure from animals, and can therefore be expected to have a greatly extended service life. The life of old fences can be considerably extended using electric fencing.

4. UNIVERSAL APPLICATION


Electric fencing will contain all types of animals, and is a positive deterrent to wild pigs and kangaroos. Educated stock develop greater respect for electric fencing than for any other type of fence.

5. FLEXIBILITY


There is no quicker or easier way to effectively subdivide a paddock for controlled grazing than with an electric fence.

6. LOW MAINTENANCE


Once your fence is properly installed and your stock are trained, the maintenance requirements of electric fencing are little different from conventional fences.

7. LESS STOCK DAMAGE


The shock from your electric fence causes no physical damage. If your stock are forced through the fence by bushfires or dogs, they are at less risk than with a conventional fence.
Here are the first basic considerations for planning
 the construction of your electric fence.
A basic fence set-up would include the following:

(1) Electric fence energizer   (solar powered, battery powered or mains powered)


This from Australian Daken Electric Fencing Manual


Electric fence energizers vary in their source of power and their power output. They fall into two groups - battery powered or mains powered. Solar powered systems are increasingly popular and involve the use of a battery powered unit used in conjunction with a solar panel.
Battery powered energisers range from very compact low power units designed for strip grazing or intermittent use, up to high powered 12 volt units designed for permanent installation on long runs of fence.


Battery life will generally correspond to the output power of the energiser.
High output energisers will require a car type battery in order to operate for a reasonable length of time between recharging.
Mains powered energizers are the preferred option for permanent electric fence applications. While they may be of a slightly higher cost, they require no battery maintenance and normally are of higher power than corresponding battery energisers.
Australian Authorities have set out a compulsory standard for the safety and construction of mains powered electric fence energisers - AS3129. Your assurance that your mains powered energiser is approved is the approval number on its label.
Solar powered energisers consist of a battery powered energiser, a rechargeable storage battery which powers the energiser, and a solar panel which recharges the battery from sunlight.


Solar energisers should be bought as a complete package because it is necessary during design to balance the power available from the solar panel with the power required to operate the energiser. This balance is needed to ensure that the fence has sufficient reserve to last through bad weather periods, whilst not waste excess panel output.
Care should be taken to align the solar panel in accordance with instructions to ensure maximum output from the panel.
With most solar panels, shade over only one "cell" will stop the whole panel. Therefore, it is important that birds and shade should not interfere with the panel.


Solar panels generate electricity from light, not heat. This means that they will continue to work effectively even on overcast days. In fact, they work best at low temperatures.

Selecting The Right Energiser


To optimise the performance of your electric fence, it is essential to select an energiser capable of performing under your prevailing fence conditions and suited to your application. The following factors should be considered when making this decision.

Is mains power available?


It is generally preferable to use mains power when it is available. Mains energisers are easier and more economical to run as there are no batteries to maintain.

The distance of wire to be energised


Daken provides an estimate of the expected range of our energisers powering a single well insulated wire under favourable conditions. These estimates have been achieved in actual tests and act as a useful guide.

The condition of your fence


A fence that may be subjected to leakages such as heavy weed growth, overhanging foliage, or poor insulation, will require a more powerful energiser to effectively power your fence than under normal conditions.
The type of animal you wish to control


The response of different types of animal will vary with the size of the shock. The appropriate shock should be designed to bring about the desired reaction from the animal that you wish to control. Often the coat of the animal provides effective insulation in which case a higher voltage shock is necessary to overcome the insulation (for instance - sheep).
"Educated" animals do not require as large a shock as do animals encountering electric fencing for the first time.

Handy Tip


It is advisable to make allowance for fence extensions you may
wish to do in the future when calculating the distance of wire to
be energized.

Energiser location


Any mains powered energiser should be installed in a sheltered position, preferably inside a building or shed. For obvious safety reasons, it should be fixed securely to a wall or shelf, out of the reach of children and animals. The output terminals (both live and earth terminals) of the energiser should be connected to the fence using Daken insulated galvanized wire.


Where these wires enter the building, they should have a "drop-loop" to prevent water running down the wire to the energiser.
Battery and solar powered energizers should be installed in an outside location, in an upright position. In the case of battery energisers, they should be located in a position offering maximum shelter from the weather. Solar powered energizers should be positioned in a North facing aspect, in an area offering maximum sunlight exposure.
Warning!!!
Before installing the energiser, read the safety precautions set out in this handbook.

(2) -Earth stakes (preferably 3)


Earthing your electric fence is considered one of the most important aspects of an electric fence that works well.

This from Australian Daken Electric Fencing Manual
Installing an Energiser
In practice, most problems which occur with electric fences are caused by poor earthing.
In order for the animal to receive a shock, there must be a good current flow from the pulsed output terminal of the energiser to the animal, and back to the earth terminal. Therefore, it is imperative that the earth terminal is well and truly earthed. Never use your water pipes, windmill, or household earth rod for your electric fence earth, because there is a definite risk of shock under certain conditions.

One of the best systems for adequate earthing consists of a series of galvanised steel posts driven at least 1.5 meters into the ground, and positioned at least 3 meters apart, in a straight line. The posts are connected to each other, and to the earth terminal of the energiser, using galvanized nuts and bolts.
Alternatively, you could use a length of galvanised water pipe instead of the steel posts, but it is harder to drive in and is difficult to connect to the earth wire satisfactorily.
 
The earth stakes should be located well away from your house, and at least 10 meters away from the earth peg of your house wiring. If possible, it is best to locate them as close as possible to the start of the fence, and in permanently moist ground, such as near a creek, dam, trough, or septic absorption trenches.
Testing Your Earth
Proper earthing is essential to the performance of your electric fence. It is therefore necessary to periodically check your electrical ground, particularly in dry periods.
 
On long fence runs, or in dry natural pasture areas, there may be insufficient moisture within the soil to provide adequate current flow through the earth return system. In these conditions, it may be necessary to establish earth connections at regular intervals along the length of the fence.
If your earthed fence wires are running through steel posts, this will help - but it is usually insufficient on its own because of the shallow depth to which they are driven and possible corrosion on the wire and post.


Intermediate earthing can be achieved by simply connecting the earth wires to additional earth stakes, periodically spaced (as wires to additional earth stakes, periodically spaced (as lustrated). Connections should be made using line clamps and insulated cable.
To test whether an intermediate earth is required, check the voltages (as shown in the illustration) using an analogue or digital voltmeter. If the two voltage readings differ by more than 300 volts, intermediate earths are required.

Where possible, intermediate earths should be established in moist ground (eg, near a dam or creek).

(3) Fence wire (polywire,hotwire,hot tape,polytape or galvanized wire)


The type of electric fence wire you use will depend on the type of fence you are building.

Strip Grazing


There are two main categories of wire generally used for strip grazing. These are plastic twine and 1.6mm soft galvanised wire.
The plastic twine, such as "Daken Hot Tape" and "Daken Poly Wire" consists of several strands of plastic (orange or white polypropylene) intertwined with a number of strands of fine metal wire, which act as conductors. The advantage of these types of fence wire is that they can be easily reeled in for transport or storage, easy to handle, are highly visible, and can be simply joined with a knot.

Recent developments in Poly Wire products has seen the introduction of "Daken Heavy Duty Polywire" which provides superior conductivity, improved visibility, and extended life - thus overcoming the shortfalls of standard plastic strip grazing wires, whilst retaining the advantages.
The 1.6mm galvanised wire provides extended life, but is generally more difficult to use, being harder to roll and join, and more prone to twisting and tangling than plastic twine.

Permanent fencing


The wire in a permanent electric fence must be strong enough to take the mechanical strain during fence construction, and be strong enough to withstand the animal pressures it is likely to be subjected to.
If you are fencing trained domestic stock, a lighter gauge wire is suitable. When controlling untrained animals, or other animals that will be trying to cross the fence, such as kangaroos or emus, a heavier gauge wire should be used.

When joining Poly Wire or Hot Tape, it is preferable to separate the wire strands so that they may be twisted and joined together. Both ends should also be knotted to take the fence strain.

In order to provide electrical continuity in the fence, you will also need some kind of line clamp and removable connectors. It is very important that all metal components in your fence are galvanised. Any brass, copper, or aluminium will corrode, leading to bad electrical joints and loss of pulse strength.

(4) -Electric fence Insulators  (offset, spring clip, wood post or steel post)

This from Australia's Sureguard

Buy properly designed electric fence insulators. They will save time & avoid frustration.Many materials that are considered to be insulators behave unexpectedly at high voltages. Plastics can carbonize and become conductive. Timber holds moisture that can allow current to flow. Surfaces conduct electricity because of moisture. Therefore, if you want to build a reliable electric fence you could save much time and effort by buying components that have been specifically designed for the job. However, if you really want to make do-it-yourself insulators then keep the following points in mind:

For most plastics the thickness of the material between the high voltage points should be more than 5mm (1/4").
The distance across the surface of an insulator should be at least 25mm (1") or more if water could accumulate on the surface.
The insulation on most domestic cables is rated to 600 volts. If you need insulated cable the proper electric fence design is about 6mm thick. You can buy a special cable on this web site that uses silicon rubber. It is flexible and easy to use and rated to 10,000 volts.

(5) -Electric fence posts (tred-ins , fiberglass , wood post or steel post)

This from Australia's Sureguard


Electric fence posts come in numerous styles. Most fixed installations would use steel posts or timber posts.

(6)-Any gates you may have will require a gate kit or at least a gate handle)


This from Speedrite electric fence systems

Interconnect live wires at each end of the fence using joint clamps. Use high quality, double-insulated
underground cable for connections to an earth system and beneath gates.
When by-passing a gateway it is essential to use high quality double-insulated underground cable
encased in a high density polythene pipe.
Bury the pipe at least 300 mm (12”) deep. Turn the ends of
the pipe down, well above ground level to keep water out.
Note:
- Ordinary non-insulated wire is liable to corrode over time when underground.
- Low quality, thin cable can perish underground or may have insufficient insulation at high
voltages. This will cause a drop in fence voltage or a complete short-circuit.

(7)-Electric fence testers for making sure your fence is operating properly.

This from Speedrite electric fence systems


Fault finding


Faults (shorts) in the fence can reduce its effectiveness and may also cause other problems, such as
interference on telephone lines or internet connections.
Causes for faults may include:
• Vegetation touching the live wires
• Broken wires or insulators
• Poor earthing
• Corroded metals somewhere in the fence-line
• Poor connections
• Poor insulation
Checking your fence regularly using a digital fault finder or a digital voltmeter is important in order to
maintain an effective, problem-free electric fence installation.
Finding faults using a digital fault finder or digital voltmeter
Electrical current flows towards a fault (short) in the same way that water flows towards the plug-hole
in a bath. A digital fault finder allows you to follow the direction of the current towards the fault,
whereas a digital voltmeter allows you to test sections of the fence and isolate a faulty section.

Digital fault finder


To find a fault using a digital fault finder:
1 Check the energizer and the earth system.
2 Starting at the leadout, work your way along the fence taking readings at regular intervals.
Always check around gateways, branches in the fence and wire joins, as faults are likely in these
areas. A fault will show up as an abnormally high reading. A sudden reduction in current
between one point and the next indicates a fault between the two points.
3 Move backwards in the direction of the lowest reading to locate the fault.
27


Digital voltmeter


Tip: When using a digital voltmeter to find faults, isolate sections of fence-line with cut-out switches.
To find a fault using a digital voltmeter:
1 Check the energizer and the earth system.
2 At the first cut-out switch (at the end of the leadout), disconnect the rest of the fence and take a
voltage reading. The voltage should be normal.
3 Move along the fence-line disconnecting a section of the fence and taking a voltage reading at
each cut-out switch. A fault will show up as an abnormally high reading.

(8)-Electric fence signs (If there is a chance the public might come into contact with the fence)

When an electric fence is installed where it might reasonably be expected to be touched by the public, warning signs must be attached.
The warning sign must be at least 200 x 100 mm in size and should be affixed to the fence at intervals not exceeding 90 meters.
The sign should also display the words ELECTRIC FENCE or show the symbol depicted.
Any lettering should be indelible, at least 25 mm high and it is recommended that the color of the sign be yellow with black inscription.
In areas prone to bushfires, power the fenceline from the 1/2 voltage terminal or turn the energizer off on days of extreme fire danger.
Do not connect an energizer simultaneously to a fence or to any other device such as a Cattle Trainer or Poultry Trainer because if lightning strikes your fence it will be conducted to all other devices.
Young children should always be supervisied by a responsible adult when near electric fencing.
If in doubt check the regulations with your local authority.

(9)-Electric fence end strainers

This from Australia’s Thunderbird electric fence systems


Electric fencing galvanised wires should be strained to around 90 kg (200 lb) High tensile galvanised wire is best as it will not stretch like soft wire and short out. Ratchet strainers are ideal for short wire strains.
For polywire or polytape fences it is still recommended to use end-strainers for longer runs so you do not put much strain on you standard insulators.

These are only the basic considerations for the construction and planning of an electric fence.
If you would like more info just email us and we can point you in the right direction for downloadable electric fence manuals.
Once you have considered these basic principles of the electric fence design you might like to email us for further assistance in planning your electric fence.

We are Australia’s largest supplier of electric fence gear.
We are a trusted eBay power seller.

 

 
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