Understanding Electric Fence Energisers

Understanding Electric Fence Energisers

If you are new to electric fencing, researching or purchasing the best energiser for your fence setup can lead to a lot of terms and jargon that may be hard to understand for the uninitiated. Different manufacturers will use different specifics as selling points and this is generally where the confusion comes when comparing different electric fence energisers from different suppliers.

The main specifications electric fence energiser manufacturers use when promoting an energisers power and capabilities are listed below. Each with a brief explanation on what they actually mean and how they relate to what the energiser is capable of.

  • Joules
    • Joules (J) stored
    • Joules (J) output
  • Volts (V)
    • Peak Volts (V)
    • Peak Volts @ (given number) Ω
  • Maximum Distance (km)
    • Maximum distance kilometres (km) of fencing (single strand fencing)
    • Maximum distance kilometres (km) of fencing (multi-strand fencing)
  • Power Watts (W)

Joules and electric fence energisers.

A Joule is a unit of energy. It is used to describe the transfer of energy from one object to the next. It is generally used to inform you how much energy an energiser has to push the shock along your fence line and when a shock is received how powerful that shock will be. The higher the joule rating is the longer an energiser can run your fence and the larger or more difficult to control animals can be contained.

Source Wikipedia

The joule is a derived unit of energy in the International System of Units.[1] It is equal to the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre (1 newton metre or N⋅m). It is also the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second.

When it comes to energisers for electric fences, there is on average 1 joule of energy per 10km of energiser rating.

When does a Joule rating matter?

The Joule rating matters in two instances when considering what the best energiser is for your electric fence setup:

  1. Boot, Kick or Shock – More Joules = more boot, kick or shock. Sometimes this is the most critical factor in determining what size energiser will be powerful enough for your job at hand. When considering an energiser for a large or hard to control animal you need to consider or research what the recommended joule rating is to control that type of beast. For a basic example, if you were to make an electric fence for an elephant enclosure that had a distance of 1km, You would not match the energiser joule rating or distance rating to the actual distance required because an elephant requires far more joules or energy to control than the 0.1 joule of energy a 1km energiser can produce. Even though you only have 1km to fence, an energiser of a 100km rating would be more suitable to ensure enough energy to deter the elephant away from the fence is achieved. for easier to control animals that have no behavioural issues like horse and cattle, choosing an energiser to match the distance rating (giving extra for fence loads like vegetation and poor connections) is completely acceptable.
  2. Distance – When looking at how far the energiser can push the stream of energy up the fence, always buy an energiser with more Joule rating than you require this will give you back up for losses in the fence line caused from things like poor connections or fence loads created from things like vegetation on the hot wires.

Joules (stored)

The Joule stored rating is the rating of energy the energiser has while its potential is stored in the components of the energiser before anything is released from the energiser and put onto the fence.

Joules (output)

One misconception we hear a lot is that battery or solar powered electric fence energisers are less powerful than mains powered energisers. This is not true.

The Joule rating of an energiser is a good indicator of both how much “boot” the energiser can give and how far it can push a reasonable amount of energy down the fence line.

Some of the more uncommon terms you might encounter are listed below, each with a brief explanation of their meaning and how they relate to a energisers capabilities.

  • Bi-polar energiser
  • Remote capable
  • Indicator lights
  • Low interference (impedance?)