Volts vs Amps and Other Electric Fence Lingo

The other day I got a call from a farmer. For the sake of this blog, we’ll call him Bob. Bob wanted to know if his energizer was doing its job. He told me he was reading 7,000 volts on his fence and had an amp reading of 2. Bob wasn’t sure if that meant his fence was working well or not. I know enough about electric fences to know 7,000 volts is a great reading for cattle. In fact, anything between 5,000-9,000 volts is ideal, but your cattle species and temperament will determine the best voltage. I assured Bob that as long as his cattle were respecting the fence, he didn’t need to worry. I offered to dig further into amperage and voltage to give him a better answer.

Before we can determine if Bob has a good reading, we need to identify the differences between amps, voltage, ohms, watts, and all the other electrical lingo.

Amperes (Amps)A unit of electric current equal to a flow of one coulomb per second.
Voltage (V)The SI unit of electromotive force, the difference of potential that would drive one ampere of current against one ohm of resistance.
Ohm (Ω)The standard unit of electrical resistance in the International System of Units (SI), formally defined to be the electrical resistance between two points of a conductor when a constant potential difference applied between these points produces in this conductor a current of one ampere. The resistance in ohms is numerically equal to the magnitude of the potential difference.
Watt (W)The standard unit of power in the International System of Units (SI), equivalent to one joule per second and equal to the power in a circuit in which a current of one ampere flows across a potential difference of one volt.

“Volts and Amps are engineering measurements used to define characteristics of an electricity supply. These measurements of a supply allow us to calculate the power a supply can deliver”

Voltage, current, and resistance are the basic units used when describing and understanding electrical flow.

Voltage Volts
CurrentAmps
ResistanceOhms

So, let’s simplify this. The most common analogy, and the easiest way to describe the flow of energy, is by comparing energy to flowing water.

VoltsWater Pressure
AmpsWater Volume

If you increase the pressure in your tank, you will, in turn, increase the water flow through your hose. This remains true with electricity. When increasing your voltage from your energizer, you increase the current, or amps, on your fence line (hose). Essentially, increasing your voltage decreases your resistance allowing for an easier (higher) flow. You can increase your energy two ways – through less resistance (more pressure) or a larger flow (larger hose).

You can increase the water flow out of a hose by adding more pressure, or by using a larger hose. In an electrical system, increasing either the current or the voltage will result in higher power.

The pressure remains in the hose, just like the power in your power lines remains when an energizer is unplugged or a light is turned off. Voltage is still present even if it is not in use.

“Current is like the rate of flow of water in the garden hose, say how many gallons per minute are moving in the hose. When the nozzle is turned off, there’s still pressurized water in the hose, but there’s no flow. When a light is turned off, the electrons are still in the wire, but they aren’t flowing – there’s no current.”

To sum up this lesson in electrical engineering, volts are equal to the amount of charge, amps are the movement of the charge, ohms are the resistance of your line, and watts are your mathematical measurement of combining amps and volts.

 

 

Now back to our original question…are 7,000 volts and 2 amps good readings for an electric fence? Based on my findings, I would say no. You should actually have less amps!

In reality, a good solid fence should have high voltage, and low amps. Although our comparison of water and electricity shows more amps = more power, when it comes to electric fences, more amps = more power = a fault in your fence line.

Yes, that’s correct, a higher amp reading indicates that more power is needed to push your voltage down your fence line. Since you are needing more power, this is an indicator that power is being pushed somewhere other than your electric fence wire. Since Bob is getting an amp reading of 2, he is losing some energy in his fence. His reading of 7,000 volts may increase if he can figure out where the energy is leaking, whether it be through a cracked insulator, poor splice, or twisted t-post, he can increase his voltage by lowering his amps. In his case, at this moment, he doesn’t need to worry about finding his fault since he is reading 7,000 volts. However, in the future, if his voltage drops and his amps increase, he will need to identify the places where his voltage is leaking.

 

Our electrical fence lesson can simply be summed up as more volts and less amps make a good fence. Volts are the power running down your fence, amps are what pushes that power down the fence. If you have a high amp reading, you most likely have power flowing somewhere other than your fence.

Have a question? Give us a call at 1-800-KENCOVE, leave us a comment on this blog, or find us on Facebook.

Our product specialists can guide you through planning, troubleshooting, and product selection.


 

If you want to learn more about the differences between watts, amps, and ohms, check out these great references and videos.

What are Volts, OHMs & Amps?

Volts, Amps, and Watts Explained.

Basic Electricity- What is an amp?

How Stuff Works- What are amps, watts, volts and ohms?

The Charging Point- Ask the experts: What’s the difference between Volts, Amps, and Kilowatt-hours? 

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6 Comments

  1. Max
    Posted September 2, 2017 at 9:58 pm | Permalink

    After a few hundred yards my fence is gradually losing strength until there is nothing left. I have checked many times for a ground fault but can’t find any thing. am I missing something?

    • Kencove Kencove
      Posted September 13, 2017 at 9:52 am | Permalink

      What is the output joule rating on your energizer? How long is your fence? It sounds like you don’t have a large enough energizer on your fence line.

  2. Posted August 22, 2017 at 9:01 am | Permalink

    I would like to know why a 12 volt battery fence charger say they put out a 12,000 volts while a electric charger say it puts out 120 volts. if you need say 8,000 volts to keep goats pen in would that mean you have to use a battery operated fence charger? please email me the answer. Thank you.

    • Kencove Kencove
      Posted August 23, 2017 at 9:25 am | Permalink

      Hi, Michael. Could the 120 volts on the charger be referring to the power outlet the AC charger works in? 110/120 volts is the standard measurement of outlets. Our largest energizer is a 240-volt charger and requires a special 240-volt outlet. Check out this site for more information about the different types of outlets and what their voltage means.

      You are correct with the voltage needed to keep goats in. All energizers have the capability of producing 10,000 + volts on the fence line regardless of their power source. You will lose this power with poor connections, broken insulators, and rusted wire. The most convenient energizer would be an AC-powered (plug-in) energizer. DC-powered (battery) energizers are ideal for places where you can’t plug in an energizer. AC units are often less expensive than solar units, DC units, or dual-purpose units.

      • Steven Druiett
        Posted September 11, 2017 at 8:36 pm | Permalink

        How many volts will a 0.5 joule charge produce? I have a 6 joule charge the generates 11,500V for my pig pen. I’m afraid it will kill my 40 lb pigs. Do I buy a new charger? What size. I should note that I have tested all the wires with a STAfix volt meter and there aren’t any faults.

        • Kencove Kencove
          Posted September 13, 2017 at 9:52 am | Permalink

          Hello Steven, a common misconception with energizers is a larger joule rating energizer will emit a higher voltage. The joule rating you should purchase is based off the size of your fence. How many liner feet of wire do you have? Do you have a lot of cross fencing? Are you using steel wire or poly products?
          Regardless of the joule rating, energizer typically generate the same voltage. The key is having a properly sized energizer, clean fence line, adequate grounding, and well-built fence to obtain the higher voltage. For example, if you had a half mile of fence, and were using a one joule energizer (which is twice the size we would recommend, but is acceptable) on a properly grounded, well maintained fence you could read 8,000 + volts. If you had a 60 mile fence and used a 63 joule energizer on a well maintained, properly grounded fence, you will also read 8,000+ volts ideally.
          The moral of the story, the voltage will be the same regardless of the output joule rating. Also, as long as your energizer is low-impedance, that high of voltage will not harm your pig. These are short pulses of energy and are simply a discomfort and are not harmful.

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