Electric Fencing - The Basics... How does an electric fence work?

In this series of blogs we are going aim to answer the most frequently asked questions and try to dispel many of the myths surrounding electric fencing.  If this is the first time you have used electric fencing you may want to read these informative blogs to understand the basics and find out how an electric fence works.  So how does an electric fence work?

What does an electric fencing system consist of?

Before we get on to how an electric fence works it is important to know what the main components of an electric fence are.  An electric fence can be powered from mains, battery or battery & solar panel.  So in very general terms the components below are what you would need for each system:

Battery System

  • battery (preferably 12v leisure battery)
  • energiser
  • an earth stake or spike
  • polywire, galvanised wire, rope, tape or netting
  • posts and/or insulators

Mains System

  • energiser
  • an earth stake or spike
  • length of lead out cable (to run from energiser to fence)
  • crocodile clips
  • cut out switch (optional, useful if your energiser is a long way from your fence and you want to be able to turn your fence off at the fence)
  • polywire, galvanised wire, rope, tape or netting
  • posts and/or insulators

Battery & Solar System

  • solar energiser or battery operated energiser and solar panel and stand (ie solar assist system)
  • an earth stake or spike
  • battery (preferably 12v leisure battery)
  • polywire, galvanised wire, rope, tape or netting
  • posts and/or insulators

How does an electric fence work?

The energiser converts either mains or battery power to create a high voltage pulse.  The pulse is very short and is then repeated about 1 every second.  This pulse is commonly referred to as a shock and is felt by the animal as it touches the fence.  The pulse having travelled through the animal then flows back through the earth to the earth stake hence creating a circuit.  The shock is unpleasant so that it provides an effective deterrent when the animal next comes into contact with the fence.  The animal remembers the unpleasant experience and avoids touching the fence again.

Below is a diagram showing in basic terms how items of an electric fencing system form a pulsed high voltage open loop with the animals being the completing link.

Earthing - how does an electric fence work?

An electric fence will work better if: 

  • a bit of thought is put in when choosing your energiser - this will save time and money in the long term.  Consideration needs to be taken of the length of the fence, the type of animal to be contained and the type of fencing being used.
  • a good earth stake is used.  An earth stake must be pushed as far into the ground as it will go.  It should be away from tree roots and building foundations.  T section earth stakes have a larger surface area and so provide a better earthing system.
  • there is no shorting on the fence - ie the live wire conductor must be insulated properly against wood, metal, foliage etc.
  • the better quality tape, rope, polywire, galvanised wire used the less resistance to the pulse therefore the better zap down the line.

Lets dispel an electric fencing myth!

An electric fence does not have to be set up as a circuit.  In theory it could run for hundreds of miles in one direction.  The only circuit that is created by electric fencing is when the animal touches the fence and hence creates a loop or circuit by facilitating the pulse to pass through it and into the ground!

If you have any questions please ask… we’d be happy to help:

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