How Electric Fencing WorksFollow this link to the Brainiac television programme for a quirky visual demonstration about How Electric Fencing Works
An Electric Fence is a circuit where a current (one pulse per second) passes through the fence wire, when the animal touches the fence it completes that circuit, the pulse travels through the animal (harmlessly) to the ground it is standing on, the energy goes through the ground back to the earth stake/s and then back to the energiser unit. The fence can be in one long straight line and it will work, it is the animal that makes the circuit.
For this you need: An energiser either powered by a battery or mains powered (often called a fencer) to provide the current; fencing wire or tape to conduct the current; insulators (or plastic posts) to carry the wire and insulate the wood or metal posts so the power does not drain to the ground; an animal to receive a shock if it makes contact with the fence, thereby completing the circuit, and an earth stake that conducts the current back to the energiser. |
All systems need the following:1. An Energiser (battery powered, solar powered or mains powered),
2. Rolls of Electro-tape, electro-rope or polywire in sufficient quantity to do from one to six strands of fence depending on the animal, or a roll of Poultry, Rabbit or Sheep Netting (no other posts or insulators needed with netting).
3. Insulators to screw into timber/metal posts and there a large variety of these available, or, use Plastic Posts which have 'wire carriers' on them and these come in different heights and 'sturdiness' too.
4. You also need an earth stake(s) - some energisers have them built in - but without one your fence will not work.
5. For Mains Energisers, insulated underground cable and crocodile clips or clamps are needed to connect the energiser to the fence and to the earth stake.
6. If using several strands of tape/wire then connectors are also necessary to connect all strands.
These are the requirements for a basic system, from here there are many bits and bobs you can add e.g. gates, reels etc. to get the final system you need.
Electric Fencers (Energisers) work by passing a small amount of current through the animal and into the ground, this then conducts back to the earth stake and so to the energiser. This circuit is best acheived in relatively damp ground conditions, it may be necessary to water your earth stake in dry weather, but we cannot stress too strongly that adequate earthing is critical to the effective operation of electric fencing systems - see video link above.
An electric fence is a less-than-ideal environment on which to conduct electricity as there are many conditions that will divert or impede the flow of electricity, so you must help to provide good conditions. Vegetation growing on the fence line is the most common culprit as it draws voltage from the fence to earth. Sagging or broken wires will also rob the fence of power. Wet weather will magnify all these problems. In particularly bad/wet weather it may be an idea to cover the energiser and battery with, say, a large plastic box.
The power of Energisers is measured in Stored Joules and Output Joules, which is the energy available to the fence to power its fence lines. Stored Joules is the energy held internally and Output Joules is the enegy released. e.g. an energiser of 1.0 joules can power up to 5 x 50m rolls of netting, or around 10km of tape.
All electric fence systems are required to comply with the relevant standards, in europe: European/British Standards BSEN 61011 220v/110v,BSEN61011-2 Battery, BS 60335-2-76 and relevant EMC Standards; United States, UL 69. |
