Seems to me that about 90% of the problems folks seem to have with predators and varmints of the furry kind (raccoons, possums, skunks, foxes, coyotes, dogs, cats, etc) could be resolved by use of an electric fence of some type. There are a lot of references to it, but not much in the way of how to. With this post, I hope to resolve some of that.

Intro:

First comes the concept of what is an electric fencer and how does it work. Short answer is it is an electric device, powered either by plugging it into an electric outlet, or connecting it to a battery. The fencer amplifies the electric charge thousands of times to send a short burst or pulse of thousands of volts down the fence line. Simple graphic is as follows:

Fencer is connected to the ground, literally the ground you stand on, and also to the fence. The ground and fence are the conductors that comprise the circuit that delivers the electric shock. The electric fencer sends a charge down the fence and unless something is touching the fence and the ground at the same time, nothing happens. Fencer recycles / reloads and fires again.....about one burst per second.....you hear it as an audible "click....click....click". It is only when the fence and ground are contacted at the same time does the circuit close and the voltage is felt by whatever closed the circuit. Essentially, whatever it is that touches the fence and ground at the same time becomes a switch that completes the circuit, where it is felt by the recipient as a painful electrical shock. It could be you if you are dumb enough to touch it, but hopefully it will be the varmint you are hoping to deter. It could also be the birds confined within. But whatever it is that touches the wire and ground at the same time will act as a switch, close the circuit and the recipient will feel a jolt as all those thousands of volts cut loose on it. The higher the voltage, the greater the pain that is felt. To really act as a deterrent, you don't want that to be a tickle. You want to knock their socks off. You want their first and all subsequent encounters to be as painful as possible, such that they quickly get the notion that whatever is on the other side of that fence is not worth it. So if you are a chicken, you stay on the inside. If you are a varmint, you stay on the outside. You want to leave them with the impression that absolutely nothing is worth crossing that line and getting zapped.

Done right, one can almost envision a scenario where a varmint could associate the smell of poultry with the jolt they got from the fence and decide to avoid it completely. Smell a chicken and run away? Maybe not as far fetched as it may seem. A varmint does not know what an electric fence is. If chickens are new to the area, and to the varmint, they may not know what a chicken is either. They only know if they touch that wire, it's going to hurt and hurt bad, and that wire is found near chickens, so they may learn to associate the pain they feel with chickens. We can dream can't we? The caveat is, it has to hurt and hurt each and every time. So in the world of raising chickens, an electric fence can be thought of as like the biblical reference to Moses and the goats blood over the door.....it is what signals death to pass you by.

Fencers:

In the world of electronics, electric fencers are an enigma. When manufacturers and users describe them, they tend to rate them with reference to the term "joules". Electric fencers are one of the few electronic devices I can think of that are rated or referenced in "joules". So what is a joule? As defined.......

joule |jo͞ol, joul|(abbr.: J )
noun
the SI unit of work or energy, equal to the work done by a force of one newton when its point of application moves one meter in the direction of action of the force, equivalent to one 3600th of a watt-hour.

Hmmmm. I'm no engineer, but that sounds like a way to measure or relate power to work output. In this regard, it would be similar to other terms we are familiar with, such as horsepower (used for engines and electric motors), foot pounds, PSI (pressure per square inch), etc. So if that is true, then the rating of a fencer in joules should be a measure of the power a fencer puts out. If fact that does appear to be the case, such that a fencer with 1 joule of output is stronger than a fencer with only .25 or .5 joules. That is what most references will say, except at least one (Parmak) says on it's FAQ page that "joules" is a meaningless measure, except they then go on to use it as such. Confusing to the max.

(Note: Joules is pronounced like "jewels". I prefer to think of it as rhyming with jowls, which also rhymes with "howls" and "yowls", which are the responses I want from my fencer).

So if Joules is not the end all factor, how do you rate these fencers and select for power. A better measure of the effectiveness is voltage. Voltage is what delivers the hurt. An article from Kencove helps explain this in greater detail:

http://www.kencove.com/fence/7_Volts+vs.+Joules_resource.php

So with this in mind, fencers are often rated as to the miles of fence they are able to charge, so it stands to reason then that one way to select them is to see how they are rated as to amount of fence they will charge. Some say only a mile or so of fence. Others 5 or 10 miles. The ones I use are rated for 30 miles of fence. 50 mile fencers are common and at least one local farm supply store offers one rated for 200 miles of fence.

Second term you need to be aware of is "low impedance". In terms we understand that simply means the fencer has the ability to overcome a fair amount of contact with weeds and brush......things that normally would bleed off the level of shock to nothing.......and still deliver a potent shock. Almost all fencers we want to consider will be low impedance fencers that deliver a short burst of high voltage measured in milliseconds.

A fencer rated for 30 miles of fence or more, and a rating of 5 joules or higher, is going to be a pretty potent weapon in your fight to keep varmints away from your fencer. Note...this is probably double what most will say is adequate or enough with most topping out at around 7,000 volts. I'm not a fan of either of those terms (adequate or enough), which to some animals, may almost be tolerable or at the least, not effective as they have fur to shield and insulate them from a mild shock. That is not the response I'm looking for. I want the effect to "intolerable" to any and all of them.

A third term to be aware of is "induction", which is referenced in the Kencove article above. Induction is the bleeding over of the electric pulse from a hot wire to a ground using only the air as the conductor, and happens when the voltage gets cranked up so high it is almost impossible to contain. It really wants to make that jump from hot to ground, so much so it may do it through the air. (A spark plug in a gasoline engine is the prime example of this). I"m OK with that. In fact, with predators, I want to push it to that level. Fur may be all I get to work with, so if it will jump through air, it may also jump through fur.

So after all that, what fencer should a person use? Generally, fencers come in two versions: AC units that are plugged in to an outlet and DC versions that run off a battery. Pros and cons to each.

AC units are generally the hottest and run at higher voltages and thus generate the most zap. They can do this since they are always plugged in to a power source and don't have to moderate anything to save battery power. In short, they "floor it".....pedal to the metal and let em have it. And with AC as the power source, the power never runs down as it might with a battery powered unit that looses it's charge over time. They can be grounded by weeds and grass and can keep going and shock right through all that. That is on the plus side. On the negative........they are plugged in. So they have to be located close to an AC power source, which may or may not be close to where you want your fence. Also, the ones I'm familiar with all say they have to be mounted inside a building so as to be protected from the weather. Imagine an electric device like this that gets wet.....it can be damaged or may damage you if it somehow shorts out and you touch it. Also, I've heard it said......and I called to ask and this was confirmed.......if the device is plugged into a GFI outlet, any shock it delivers to an animal can trip out the GFI breaker, shutting down the unit. By code, nearly anywhere you would install such a fencer is going to require a GFI outlet, so if you used one in this situation, it is almost designed to fail. That's not good. Probably the best use for an AC powered charger is inside a barn, shed or home, used with a long distance of fence (10 acres or more) that is more or less permanent. It could also be mounted inside a permanent chicken house with a permanent fence running from this house and protecting a sizeable area for the flock to run around in.

To get around the GFI issue, forget code and do not use a GFI outlet. Dedicate a circuit to it that is not used for anything else and mark it as such. An AC unit also needs to be protected from a lightning surge, which will fry it's circuitry. Lightening damage comes from both the AC power source and also from the fence itself, so protection needs to be installed from both directions. A surge protector on the front end and lightening arrestor on the fence side. A lot to like about AC units, and a lot not to like as well.

DC Units come in two flavors. Simply tied to a battery, or to a solar powered battery. In general, these are not as hot as AC units, and likely they do this to conserve battery power. Solar powered chargers will keep a battery hot for a long period of time......maybe always, but tend to be more expensive since you are buying not only the fencer, but battery and charger all in one unit. But if you also have to buy a separate stand along battery and a charger, then when you add all three of those together, the solar unit is not as expensive as it may seem. But as to battery powered units, the nature of fencers are they really don't use much power except when they are actually delivering shock, so unless they are grounded somehow, they are not pulling much juice. A fully charged deep cycle battery may last a month or two between charges and a solar powered unit may indeed be able to keep up with the juice required to run a fencer.

I'm using 12 volt fencers that connect to a deep cycle lead acid battery. These fencers are rated to deliver up to 13,000 volts, and mine are.

These are made by Parmak in Kansas City, and sold as rebranded units by our local farm coop. They are the Parmak 12 battery powered units. They pack a wallop. I put a fence tester on them and they do deliver the 13,000 volts shown on the meter. That would hurt. I once saw a cow touch her nose to a single wire fence powered by a fencer like this........she was about 50 feet or so away from me when it happened. I saw a blue spark jump from the fence to her nose and I heard it snap. I also heard her grunt and she didn't stop running until she was about 100 feet or so from that fence, where she turned back to stare at it, wondering what it was that hurt so much. That is what you want the varmint to experience and you want the same response.

As to fencers, I don't want to get caught up in brands.......there are lots of them on the market and I suspect they all work and work well, provided you get one that packs a wallop. A tickle doesn't count. A wallop strong enough to loosen their teeth will. Whatever you use, make sure it packs a wallop. This is especially important with varmints, which tend to have a longer fur, which protects them to a certain point. It does not protect their nose or tongue if they can be tricked into licking the fence, but if they were to try to crawl under it, it might.

The need to Ground:

Key to get good performance from any fencer is the need to establish a good ground. Connecting the fencer's positive hot wire to the fence is easy. No loss there. The ground or negative side, however, is the other half of the circuit and needs to be every bit as good, since the ground......again literally the "ground you stand upon" is the conductor for the negative side of the circuit, serving the same purpose as the fence wire does.

So what constitutes a good ground? The short answer is "enough", and it is utterly amazing the lack of understanding as to what constitutes enough. Enough is simply a good enough ground to act as a conductor between the hot wire and the ground you stand on such that the full potential of the fencer is realized. The best way to measure this is with a fence tester. If you test your fence and you are at your fencer's full potential, you have a good enough ground. You could add 100 more rods and it won't get any better. Enough is enough.

To give some examples of how poorly this is understood, I would like to offer three examples of how fencers were being grounded. All three examples are presented as videos. The first is by an end user and the other two are by folks who make and/or sell this equipment:

On the above video, notice the extreme this guy went to to establish what he thought was necessary for a good ground. More on this one later. Grounding the middle wire is an important consideration for some fence installations.

Below, aside from seeing how poultry netting works, fast forward until they get around to setting up the chargers and note the difference between what they use for a ground, and what the first guy did. Note also what type of ground is used to test the fence. If that is all that is required to test a fence, how much is required on the front end to deliver it? Hint: the same amount.

In general, what establishing a good ground means is you need enough. For some, they see the need to pound a long metal rod......or rods.......into the ground at the fencer's location. Some will pound in multiple rods and even try to locate them in wet areas or even pour water on the ground near the ground rods to enhance the connection. That may be required in areas where the ground is dry and you can't get good contact, but if that is the case, then ground the animal is standing on isn't a good ground either, so other options may need to be considered. BTW, the "ground" used for my fencer shown above is a 100 foot section of woven wire fence, with steel fence posts set at 10' intervals. So the ground I used for this setup is about 8 or 9 steel posts driven about 15 inches into the ground, some in wet locations. I'm maxed out on my fencer's ability, so my ground connection is good and my fencer is HOT!

Fence types:

If you go to a local farm store, you are going to find two basic types of fencing materials. They are poly tape or poly rope, and wire.

In general, poly tape is intended for horses as it is wide and thus visible to them. They can easily see it. It looks like packing tape, and is made of plastic, except it has small threads of wire running through it that carries the current. Horses don't have fur to protect them so they feel the shock and are sensitive to it, so the fence does not have to carry much current to be effective. The cheap poly tapes don't carry much current, and have limitations on how long the fence can be and still be effective.....about 200 meters or 650 feet or so. More than that and they suggest a better grade of tape. Yes, they do make different versions, some with higher wire count so are more effective, offer less resistance to current and can handle longer runs. These are also more expensive. Poly tape and turbo tape......there is a difference.

Poly ropes work the same way, except instead of tape, they use rope with wire spun into the fiber mix. Some as small as 1/8" and as with tape, the better stuff with higher wire count is larger in diameter in the 3/16" range. Same issue with metal counts. The smaller stuff has less metal and is less effective. Larger stuff, more metal, so more effective and for livestock, also more visible. Poultry net fencing uses the same type of rope, except it is woven into a fence with multiple strands attached. More on this in a moment.

For our purposes, wire will generally be found as one of two options. The first is a lightweight 17 gauge aluminum wire; the second is 14 gauge galvanized steel, which is not lightweight, nor is it very flexible. Once you get into large pastures for large livestock, wires may get larger still, like #12 or so. These may be stretched tight (high tensile) and permanent. If you really want to make a permanent electric fence, you could consider going larger and heavier. It will be more durable.

Wire offers almost no resistance to current, so can be used for really long runs....miles long runs....with almost no drop off in wallop. Wire is shiny, and thus visible, the heavier steel wire being more visible and durable than the lighter aluminum.

What you won't find in the local farm stores is electric fence poultry netting. You will likely have to get that online. Two most common sources are Premier 1 in Iowa, and Kencove, which is based out of PA:

https://www.premier1supplies.com/c/fencing/electric_netting/

http://www.kencove.com/fence/Electric+Net+Fencing_products.php

Poultry netting is made of the plastic rope, with wires included in the plastic. It is woven together to make a fence. The horizontal bands are hot wires......the vertical are inert plastic used to create the grid and to hold the thing up and together.

Fence looks like this:

The strands of wire in the fence looks like this:

Once up, it looks like this:

So if this fence is hot and anything.....bird, varmint.....you.....touches one of those green bands, they are going to get zapped. So birds stay in and varmints stay out. Setup right, and for small areas, this is probably the most effective fence going, but does have it's share of problems. Which are? It is temp......you set it up with step in posts, which are built into the fence. That is good in that it goes up quick, but over time, tends to sag under it's own weight. Also, the bottom strand is not hot, but the second strand is, and the second strand is only 3 inches off the ground. Any weeds, grass, etc, not to mention a fence sagging enough to touch the ground will ground itself out, reducing the shock it delivers, and shortening the battery life. But since it is temp, you pull the posts, move it off to one side, mow tight to the ground and then set it back up. A weedeater will do a number on one, so be careful if you try that. You could also clear a pathway for it using Roundup or some such plant killer. You might try that if you want to put it up and leave it up for long periods of time. A fence of this type works well with tractors as a way to enlarge a pen surrounding your portable coop. You would want to couple that with a portable (meaning DC powered ) fencer.

This fence, for the area it covers, is also the most expensive. Fence shown above came from Kencove........164' fence, 48" high and it was roughly \$180, plus shipping. So 164' of fencing would enable a protected perimeter of 164 feet. Roughly 40' x 40', or 20' x 60', 10' x 70', etc. The closer to square you are, the more interior square footage you get. You can also tie them together to expand the area covered.

Wire and poly rope cost a fraction of that, so can be used on larger areas, in fact they may be best used for larger areas, and for a couple of reasons. First is the cost factor. A person could fence in an area of several acres for less money than a single poultry netting would cost. At least as far as fence that would keep predators out. But that comes with a caveat........it may not keep the birds in. Some say yes it will, and others say no it won't. I'm in the camp that says it all depends. Depends on what? Mainly how large is the area being fenced in. Large enough, probably it will......tight quarters.....maybe not.

To elaborate, laying hens, which is what I'm referencing here, only want to range about 100 yards or so max from their home base......generally their coop. So that is about 300 feet in any direction, or if the coop is centered, 300 feet in any direction, so 600 feet square. That is roughly 8.2 acres. So with no fence at all, a free range flock of birds may not venture outside that range, fence or not. If you put up a fence around such a large perimeter, the birds may never venture far enough to find it, but a predator coming from outside that enclosure might. Depending on the terrain, it would be an easy task to build a simple fence to keep them out. It would like like this:

This fence is what a fellow I know is using to keep raccoons out of his sweet corn patch. It uses two strands of poly tape, the lowest set around 5 inches or so off the ground, with a second about 10 inches or so above that. A raccoon trying to breach that perimeter is likely going to hit it with his nose.........again, he does not know what a fence is, he only sees a horizontal object to crawl under, over or through. But likely as not, he will touch the fence one way or another on his first encounter and when he does, he gets zapped, and zapped hard. So he decides nothing is worth that and goes off to forage elsewhere.

As shown, this is being used to protect a patch of sweet corn, but the same concept applies to setting up a perimeter to protect a flock of birds. Varmint is on the outside, birds on the inside and he has to get past that fence to get in. Can he do it? Will he do it? If hot enough, and painful enough, probably not.

Realistically, this may be all the fence that is required to keep most of our varmint predators out. If they can't go under it and can't go over it, what else is there? Simply establish one of these as an barrier that they cannot cross. (Keep in mind, a tree canopy is a highway for raccoons to get over it. Go up one tree and come down another.....so you would have to either fence all those trees in, or fence them all out).

This is a similar fence I'm using on my garden, which also has sweet corn in it:

Instead of poly tape, I'm using 17 gauge aluminum wire, the lowest set about 5 inches off the ground and is suspended by white plastic step in electric fence posts. The second wire is 5 inches above the first. As per my fence tester, this fence is packing 13,000 volts of wallop. To date, it is holding. Within 48 hours of setting this up I went out early in the morning to find my the fence was down. Fencer was still running and till shocking, but at a reduced rate because it was now grounded. But fence had been knocked off the insulators so something hit it hard. Judging from the stank, the first varmint to encounter my fence was a skunk and the jolt he got was enough to not only cause him to knock my fence loose, but also he let loose on the ground, hopefully from a fence induced incontinence. No issues since.

I managed to hit this fence with my weedeater and it knocked things loose. If this is intended to be more permanent, the heavier 14 gauge galvanized steel wire is stronger and more durable and will stand up to more abuse. It is also more visible. It is not as flexible and not as easy to use, but is more durable. In my case, I plan to switch to a lawn mower and simply mow under it, moving the step in posts as needed to get a clear pathway.

Flagging tape was added after lady I'm married to forgot it was there (this light wire fence is not as visible as some) and walked into it. If not for the fact they were wearing some fairly thick flip flops, she would have gotten zapped and my life may have ended. So I added the flagging tape as a visible reminder. One could also add some string above it to get the same affect. But as is, it is protecting and can be easily stepped over by those who know it's there (people that is).

So in addition to keeping varmints out, will it keep chickens in? Some say yes, some say no, I say it depends. This fence is set around a garden area of about 50 feet square. The birds will be free to test it, but so far, they have not ventured this far out. However, at nearly 9 weeks of age, they are now large enough they will not be able to slide under it without touching it. So once shocked, they may learn to respect it and not get anywhere near it. So on the ground, probably it will keep them in. Will it keep them from flying over it? Probably not.....if, and this is the big IF, they are so confined that they feel compelled to escape the enclosure and fly over it, OR, are somehow startled by a dog, predator, etc, that is on the outside and bum rushes them into a panic induced flight that takes them over it. But I'm told the same issue exists with the poultry netting fence.........birds inside can be induced into a panic flight by a charging dog, etc, that takes them outside the pen where they can be caught. They don't make one high enough that most birds cannot fly over if they really wanted to.

One additional benefit of the low single or double or triple wire fences is with the birds themselves. If they do somehow manage to find themselves on the outside, a single bird or two trying to rejoin their buddies will eventually work up the nerve to punch through these to get back home, and even more so if a varmint is in hot pursuit and they are fleeing for their lives. Not so much if they are outside a woven wire or some other high wire fence. They are trapped and easy prey.

OK, to return to the issue of grounding and what to do if your soil is dry and or frozen or for whatever reason, the soil is not conducting a charge well.

Back to the guy on youtube protecting his sweet corn from coons:

Again, forget about all the multiple grounding rods and such and note how this guy has included a third wire in his setup. The middle wire is not hot, but is grounded. As per the guy that produced this video, his claim is coons and varmints will not crawl under the low wire, but over it and through two wires. By putting in a middle wire and grounding it, the coon is almost certain to get zapped. Others will use a full three wire setup, with all three being hot. That may be overkill, or not depending on the severity of your problem.

But adding this third middle ground wire is actually a variation on an electric poultry netting option you can buy, in which the horizontal bands in the fence are not all hot, but alternate between hot and grounded. Again, this way you don't have to rely upon the ground (again, literally the ground you stand upon) to be the conductor for the negative side. The fence itself it also connected to the ground so is as good a connection as can be had.

Graphic looks like this:

Even More Fence Options

One of the problems with these low wire fences is to be effective, they have to be that close to the ground to keep the varmint from sneaking under it, so there is a constant maintenance issue to keep the weeds and grass from shorting them out. Powerful, low impedance fencers are designed to punch through this so as to continue shocking, even though the fence is grounded by weeds. I can only imagine, however, if this is a DC unit, such use will shorten battery life as the juice gets drained off through the weeds, not to mention a less violent shock delivered to the varmint.

Yet another fence option is a fence used by an experienced user and coon fighter I met a few years back.

For this fence, he simply pounded in some 2" x 2" x 2 foot wooden stakes, the kind used for setting up light concrete forms, laying out foundations, etc. (you can buy them pre-made at the box stores and lumber yards). To this he added about a foot or so of chicken wire, leaving a couple inches of wood stake sticking out on top of that. In the ends or tops of the stakes, he nailed in electric fence insulators, the kind you nail into fence posts. So he then had a single hot wire, but it was running about knee high and well up off the ground away from weeds, grass, etc., yet low enough a person could still step over it (carefully!) without getting shocked. I don't think he even had a gate....to come and go he was simply stepping over it. So a coon or other varmint encounters the fully grounded chicken wire fence, tries to climb it and when he reaches the top, grabs the hot wire with his grubby little paws and gets blasted into next week. This fence has the added benefit of also being about belly high on a deer. Not high enough a deer will jump over it, but just right so they will simply step over it, brush the wire with their belly and also get blasted into next week. This fence required a whole lot less maintenance than a low wire and would be more permanent in nature. He was spraying the ground on both sides of it with Roundup to keep ANY weeds and grass from growing up through it.

Yet another variation on this knee high fence, if you don't trust chicken wire, is to use the same type setup, except in this one, you use a heavier welded wire in the 2" x 4" range, using the same L shaped apron trick used to keep predators from digging under our runs and coops. (In the graphic above, the first option is only the vertical fence. The second option being described here includes both horizontal and vertical fence sections). Half on the ground and half on the fence posts (ideally steel posts which when connected to the fence make a direct ground), with a single or double hot wire on top they have to reach onto to climb over. Not so high as to induce a fox or coyote to jump over, you want them to try to climb over by putting their paws on top and BAMMO! Again, less maintenance than a low ground wire. Similar to a plastic rope poultry net fence, but less expensive and more permanent in nature. On this one, they can't go under it......can't go over it.....and can't go through it. The ultimate perimeter?

Update:

Had a question about electric fences for bears....fence type and fencers to use. In response, I found this video, which in my opinion is very good.....both about bears and electric fences in general. I was a bit surprised how often they are using the poly tapes and poly ropes, but if it works, it is a great option. They are highly visible and bears don't see well. They do have incredibly good sense of smell, however, so anything you can go to get them to sniff the fence will help them find it.