How Powerful of An Electric Fence Do I Need?

How Powerful of An Electric Fence Do I Need?

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If you’ve decided that an electric fence is what you need to keep your property secure – whether that’s keeping animals in or something out – you’re probably right at the beginning of the electric fence process.

However, since most people don’t know too much about how electric fences actually work, you probably have lots of questions. One of those is probably how powerful of an electric fence do you need. Here’s what you need to know.

How Is the Power of An Electric Fence Measured?

The first thing you need to know about electric fences is that when it comes to how powerful of an electric fence you need, it’s not the volts you need to focus on.

Most electric fences have a specific voltage rating, but that’s just the voltage of the current that is flowing to the fence. That doesn’t determine how powerful your electric fence is, just how much of a shock it will deliver.

Instead, if you want to measure the power of an electric fence, you need to know the power of the electric fence energizer, and that is measured in joules.

What Is a Joule?

Joules are SI units that measure energy or work.

In simpler terms, in order to measure anything, we refer to the System of Units, which is administered by the International System of Units. This is a global system that has standardized units of measure. So this is what decides how much a kilogram actually weighs or how long a foot, yard or meter actually is.

That organization has decided that one joule has a specific amount of energy.

In the mechanical world, one joule is the amount of energy required to move one newton.

In the electrical world, one joule is one watt of electrical power applied for one second, or as it’s also known, a watt-second.

Fortunately, you don’t have to understand or remember all of that. All you need to remember is that electric fence energizer power is measured in joules.

How Many Joules Does Your Electric Fence Need?


The next question you probably have when you’re trying to figure out, “How powerful of an electric fence do I need?” is how many joules your electric fence will need.

The answer is that this depends.

Electric fences are circuits, and they’re made up of many fence wires, which are resistors. The strength or joules of your electric fence energizer need to be sufficient to generate enough power to flow through those resistors.

Fortunately, electric fence energizer manufacturers have made it a little easier to figure out how much power your fence will need and how many energizers you will need to achieve that amount of power.

Electric fence energizer manufacturers will usually tell you not only how many joules of energy their energizers will provide but also how many miles or kilometers of wire that energizer will power.

It’s important to remember that those figures are for all of the wire strands on your fence. So, for instance, if you have a four-strand electric fence that is 2 miles long, you’ll actually be powering 8 miles of electric fence wire.

The good news is that unless you have a very long fence or you need to have multiple zones for monitoring purposes, in most cases, you will only have to have one energizer to power your fence.


Always Read Product Datasheets

When it comes to more complex types of fencing, like electric fences, it’s a good idea to always request and read the manufacturer’s datasheets and product documentation before you select the products and specifications for your fence system.

This will help to ensure that you choose the right products, equipment, and specifications to deliver a fence that works well and will give you years of trouble-free service.

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