Choosing an Energiser

Make sure you choose / select a suitable energiser.

Selecting an energiser may be the most confusing decision possible. The decision rests around a few variables.

1/. How much wire will you be energising? For example, if your fence will be 700 metres long and will have 2 energised lines then the length required is 1400 metres, 3 then 2100 metres. This would be the minimum and consideration needs to be given for future expansion, vegetation challenge and a bit extra to be sure.

2/. What is the conductivity of the rope/tape or twine (conductor) you will be using? A conductor with a higher resistance (measured in Ohms per metre or Ohms/m) will reduce the amount you may put to a particular energizer. All length indications given by companies assume good quality (0.05 Ohms/m) fence conductors are involved.

3/. For example:- An energizer capable of energizing 9klm with a 0.05 Ohms/m. conductor will be reduced to just 1.3klm if you use a conductor of over 10 Ohms/m.
Conversly, the above energizer will use far less energy in a fence of 1.3klm when a conductor of 0.05 Ohms/m is used than the same fence using a conductor of 10 Ohms/m. A big saving on battery power.
The lower the quoted figure is, the better it is

4/. What animal is being controlled? Sheep and poultry have good insulation from their wool and feathers - use a higher voltage rating energiser even if the fence is short (hotSHOCK) or Farmer range.) the higher running voltage bridges the wool or feathers. Pigs, horses and dogs are easily controlled.(Most others are suitable) A wimpy energizer gives you a wimpy fence, don't skimp here if you want the job done.

5/. Some energizers simply push out the current and are generally cheaper (but cheerfull), others have all sorts of bells and whistles and can be very handy, cheaper, safer and easier to use in the long run than the basic models.

All are supplied with a manufacturers three year warranty (Excludes water immersion and lightning strike)

An explanation of some of the ratings applied to Fencing Energisers.


The energiser's electronic circuitry takes electrical energy from the power source [mains or battery] and accumulates it in the storage capacitors. This energy is the stored energy within the energizer but not necessarily available to the fence and is measured in joules. 1 joule almost equates to the amount of energy required to lift 2 kilograms against gravity to a height of 1 meter. As the amount of energy actually transmitted to the fence is affected by the internal electronics, it is not advisable to use this figure as a comparison. The closer this figure relates to the Output figure - the more advanced the electronics.


Triggered by electronic circuitry, the stored energy is discharged through an output transformer to the energiser's fence terminals. Some energy is lost in this process so Output energy is always lower than the Stored Energy. This output energy is the effective energy applied to the fence and is measured in joules. THIS is the figure to use when comparing energizers.

500 Ohms?

Energy available under a load of 500?. This is the equivalent of a mammal touching a fence. The closer this is to the Output rating, the better the circuitry will handle a load on the fence and is an ideal way to compare between different manufacturers.

Mains Energizers

If your pasture is near an electrical outlet then using a mains energizer is a shoo-in. They are stronger, cheaper to run and don't need batteries. All mains units are supplied with UK specification plugs and electrics. They do need Long earth stakes, a connection cable to attach both the earth stakes and to the fence. This is not supplied as the distances vary and High Voltage Insulated Cable is recommended.

Where a mains energizer is located within a fire-risk building it is advisable to include a Lightning Arrestor between the fence and the building.

9 volt Energizers.

9 volt units are very portable, light-weight, easy to use and handy. Technological advances in batteries give them excellent life and they are housed within the energizer resulting in a single unit. These are ideal for most situations around equestrian yards.

12 volt Energisers.

More powerful than 9 volt. Generally used with re-chargeable batteries, an alternative is needed whilst charging takes place. A car battery is designed to have a rapid drawdown of power with constant re-charging so does not last long, so a 60aH leisure battery is better. Due to delivery legislation, wet 12v batteries are not available. Long earth stakes need to be purchased

Anti - Theft Energisers

There is a range of Energisers designed to combat theft by a range of methods. These use GPS tracking to provide you with a constact location allowing you to locate your energiser. This anti theft tracking system proved a success within months of their release.

Remember that animals will learn not to touch a wire with 6,000 volts running through it.

This Table will give a guide to which energizer may be suitable to your situation. The horiSmart range do have additional safety features incorporated in their design.
The Maximum length is a theoretical figure if your fence was in perfect order and the best conductors have been used (0.05 Ohms/m). It is advisable you use a figure about 60% of that stated. If there will be considerable challenge from vegetation, opt for the hotShock or Farmer range as they are capable of handling greater pressure.

This table gives a comparison between the various Electric Fence Energisers indicating their capacities.


Max Length Klm$

Max Voltage 1000v 500 Ohms, 1000v Nets Joules# Power Source
EquiStop B1 3 7 3.5 1 0.18(0.12) 9v or 12v*
EquiStop B2 8 7.5 3.5 2 0.3(0.22) 9v or 12v*
EquiStop A2 30 8 3.6 4 1.5(1) 12v
EquiStop M3 48 8 3.8 6 3(2.3) Mains
HotShock A15 40 9 6 7 1.5(1.3) 12v
HotShock A50 80 12 6.5 15 4.2(3) 12v
HotShock N50 120 10 7.5 18 6(5) Mains
Copel A2
30 8 3.5 4 1.5(1) 12v
Copel M2 25 9.7 4.7 4 1.5(1.2) Mains

*To run these units on 12 volt power an additional connection is required.
# Stored(Output) Joule rating respectively.
$ Average fences will be about 60% of this figure.

Whilst every effort is made to maintain this table, the details in the principal featured pages will prevail.