Advice How does an electric fence work? Applications & usage Choice of materials Installation Earth testing Installing the earth system Checking the earth system   How does an electric fence work An electric fence, which can be either battery or mains powered, converts this power into high voltage pulses. If the wire carrying the pulse is touched by an animal, the current passes through the animal to the ground, and this effect gives a shock. As the animal realises that the fence causes pain it quickly learns to stay away, and the fence becomes a physical and psychological boundary. Applications & usage Cattle and dairy Cows These are easily fenced with the minimum of problems. Milking cows which are already used to an electric fence can normally be strip grazed using a single strand of polywire or tape. Sheep/Goats Sheep have longer hair, which acts as an insulator, and therefore they require more power or a stronger pulse. Horses Energetic and lively ponies and horses are easily fenced. The electric perimeter provides containment, safety and security for the animals. For the fencing it is recommended that tape be used to enable the horse to see the boundary easily. Pigs Again the fence needs good visibility. Where large and small pigs are contained together, distance between the fence lines and number of lines are important factors for consideration. Other Applications Game, Deer, Rabbits, Foxes, Chickens, Dogs, Cats, Etc Choice of Materials The Basic principle is to achieve a balance between the different components of an electric fence. For instance, using a powerful fencer with a low conductivity wire, which has been badly installed and not maintained, will give poor results and unsatisfactory service. The Energiser The heart of the system! There are many models available depending on the power supply and output required, the fence length, and the type of animal to be contained or excluded. Mains Fencer 230V : these are best for large areas where a permanent fence is required. They will also, when earthed correctly, burn off any vegetation. An example of a large mains fence would be the FORCEFIELD MX9 with built-in 7-light Voltage Level Indicator and audible Low Voltage Alarm. Dry Battery 9V : these are best for short or temporary fences where portability and flexibility are the main considerations (B20, B30 or B50). Wet Battery 12V : these allow you to use rechargeable batteries and facilitate a more powerful battery powered energiser (B12 for strip-grazing, BM140 for bigger applications) Insulators Good quality and correct selection is essential to ensure the efficiency of the fence. The choice depends on the type of posts, wire or tape being used. Your dealer will assist you in making the correct choice. Posts If a permanent fence is planned, chemically treated softwood posts with insulators, or non-conductive hardwood posts are ideal. Steel, Fibreglass or plastic posts can be a viable alternative. If it is a temporary fence for strip grazing, plastic posts offer portability and ease of construction Conductors These come in a variety of forms from high tensile or stranded steel, aluminium poly wires, plastic tape or rope; each appropriate to specific applications. Plastic based products should be treated for UV exposure and be strong in tension. Woven or twisted wires provide durability and strength .The electric conductive part is made from stainless steel for mechanical strength and is used mainly for temporary fences where it can be rewound easily for moving without causing too much wear and tear. Tinned copper gives excellent conductivity for large area or permanent fencing. The copper wire is far less durable than stainless steel however, and while being a better conductor will stand up to less wear and tear. Careful consideration of the numerous products available is most important when making the appropriate choice for a particular situation/application. Checking the Installation The connections between energiser and fence should be firm and well joined. If wires are passing through a wall make sure that they are properly insulated. If this is not done then there is a possibility of power loss to the fencer All installations must be open circuit with the outgoing wire fully insulated to avoid shorts to earth. This means using good quality insulators and avoiding vegetation growth or other items touching the wire fence. All joints and connections should be made using the correct joiners for the purpose to ensure that they are safe and secure. For a permanent fence regular inspection of the line is essential. Weeds and branches touching the line should be removed – with the fence powered OFF. Any vegetation in contact with the fence reduces efficiency and performance, particularly during damp and wet conditions or periods of lush growth. Visibility of an electric fence is very important too. The animal will remember the shock it received and will respect the fence as a barrier, and so it is essential that it remains visible; also allowing a person to see and avoid it. To obtain maximum long-term effect, a training period of 24 to 48 hours during which the animal is allowed to touch the fence and receive a shock is essential.   ALWAYS Use enough earth bars Use galvanised wire at all times Place earth bars about 3 Metres apart Seal all joints NEVER Place an earthing system within 10 metres of a household or domestic earth Earth Testing Without an earthing system for the energiser, there would be no shock on the fence line. An earthing system works in much the same way as an aerial does for a radio, but instead of collecting airwaves, the earthing system picks up electrons from the ground, which are transmitted with each pulse out along the fence line The stronger the energiser the better the earth required Electrons are widely spread in the soil but they are more available in moist or mineral soils then they are in dry stony soils. Therefore before deciding how many earth bars are required, take three factors into consideration: - The type of soil - The type of energiser High or Low Power - The load one can expect on the fence line from vegetation, faults in the system and the length of fence Installing the Earthing System Always install one or two extra bars to be sure. The rule of thumb here would be to install a better earthing system than is required. Having decided on the amount of bars required, dig a trench 150mm deep from where the first bar is going to be, to where the last one is. Using 1M earth bars, drive them down until they are flush with the ground, and then connect heavy duty earth cable between each of the bars. Then take the cable from the last bar and connect it to earth terminal Check the Earthing System When the earthing system is installed, it is vital to test it. To do this, first simulate heavy vegetation loading in the fence line. To do this, place an iron bar in the ground about 100M out along the fence and lean it against fence wires. Plug in the energiser and check the voltage reading along the fence line. If it reads around 1000 volts or less, a sufficiently heavy load has been put on the energiser. If the voltage is still above this, place more iron bars along the line until the voltage drops to 1000 volts or less. Leaving this load on the line, take a voltage reading on the earthing system. A small reading on the earth wire is permissible as long as it does not exceed 300 volts. If it does exceed 300 volts, the earthing system is not sufficient, and you will have to install more earth bars.