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Electric Fencing ... The Basics - Energisers

Energiser – the power behind electric fencing….

Thinking of using electric fencing to keep animals in and/or keep predators out?  Perhaps 47HMX1600__01you have had a look at electric fencing but it seems such a minefield you are not sure where to start?  Don’t be put off– it is easy, simple and safe to use. One of the key components to a good electric fence is an energiser, energizer or fencer.  A little planning at the outset will save you time and money, helping you choose the right energiser.  Here are some guidelines and tips to help you through the maze.

What does an energiser do?

In brief the job of an energiser is to convert power (from mains, battery and solar) to pulses and push them down the electric fence line.  The pulses are of high voltage and low amperage, which makes them, like static electricity, safe but an unpleasant experience when touched.  In general terms for a longer fence you need a more powerful energiser – it must be able to push the pulse and at the same time maintain its voltage.

Energiser ratings

Energisers are comparable through these ratings:

Stored Energy – The energiser takes power from a power source (mains or battery) and it accumulates this power in its storage capacitors – so stored energy is the power it creates.  This energy is stored within the energiser – the smaller the stored energy the smaller the length of fence the energiser can power.

Output Energy – 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 energy that goes down the fence and is measured in joules.

Consumption – the power source will be used more quickly depending on the power of your energiser – please take the length and type of fence into consideration.

Distance – the estimated maximum distance the energiser will power.  This figure is based on the highest metal content fence line such as high tensile wire and assumes perfect fence conditions and a suitable earth system.

What type of power source?

Mains Energiser – the preferred option, mains power is reliable, cheaper to run (can be as 47HLM100S__01 little as £2 per month) and less hassle than battery powered systems.  It is this simple: plug your energiser into the mains, the energiser converts the power and the pulse is taken out to your fence through lead out cable.  Lead out cable comes in 25m, 50m and 100m lengths and can also be joined to cover longer distances.

Battery Energiser – your electric fence may be too far away from the mains and so battery power is the only option.  Energisers can be powered by different batteries:

1. D-Cell battery powered energiser for small distances, strip grazing, gardens and pond protection (up to approx. 400m).

2. 6 or 9 Volt battery – very portable, light-weight, easy to.   Generally have an excellent life and are normally housed within the energiser making it compact and easy to transport.  These are disposable batteries – non re-chargeable.

3. 12 Volt – most powerful of the battery options.  Re-chargeable batteries – make sure 47HLB525__01you have a replacement when charging is taking place.  Use a leisure battery and not a car battery.  Car batteries are designed to release power quickly and so need charging every couple of days.  Leisure or agricultural batteries are slow release and will not need charging so often (should last 4-6 weeks approximately).

Solar - If you are tired of expending electricity and muscle power bringing your energiser batteries in to charge - then a solar energiser or solar assist system is your answer – both systems trickle feed 12v batteries extending the period between conventional battery charging.  The level at which the panel will extend the life of your battery is dependent on the power of your energiser generic fire drake-001(the more powerful the energiser the higher watt  solar panel you will require) and the duration and strength of available light.  A Solar Energiser – has an integral solar panel permanently fitted onto the energiser – these energisers still require a 12v leisure battery.  A Solar Assist System – is a solar panel with stand and connects directly onto a 12v battery. These solar panels can be fitted to most battery powered energisers.

Dual powered energiser – some ranges of energisers can work off mains or battery.   These energisers will come with all the accessories you need to run either system.

What to consider when choosing an energiser:

Which type of fencing are you putting up?

You may be putting up a short strip grazing fence for horses (using tape or rope) or perhaps protecting poultry with netting, whatever the type of fencing it is worthwhile reading the energiser ratings carefully.  It is advisable to choose a strong energiser for powering electric netting as the netting can easily touch vegetation which causes earthing and so power loss.  So a rough guide to determine which energiser to use – length of fence x the number of lines of tape/wire/polyrope/netting plus 50% for future expansion or shorting (check this against the energiser distance rating).

Which type of animal are you protecting or protecting against?

A stronger energiser should always be used to contain or exclude animals which are carnivorous or are well insulated.  Sheep, rabbits and poultry have good insulation from their wool, fur and feathers – it is advisable to use a higher voltage energiser even if a fence is short.  The higher running voltage bridges the wool, fur or feathers.  Pigs, horses and dogs are generally easily controlled by electric fencing.  A weak energiser will give you a weak fence and that simply just wont do the job!

General Tips:

Earth Stake – An earth stake is an integral and very important part of any electric fencing system.  Without an earth stake the system will not work

Testers - Most manufacturers say that an electric fencing kit or system is not complete if it does not have a tester.  There are three main types of electric fence tester: proximity testers, probe testers and self earthing units.


There are countless types of energisers on the market – in many different shapes and sizes.   Work out the distances you are going to cover and which type of power you are going to use and if you are still bamboozled and unsure – get advice and help to get the correct energiser from the outset.  An electric fence is only as good as its components and construction!

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Meriel Younger

About Meriel Younger

Farmers daughter (my mother was the farmer!) with many years experience of farming, equestrian and electric fencing. Living the 'good life' and forever trying to find the perfect work/life balance!

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