A treatise on Electric Fencing

[Howard E]

I would like to suggest some phrasing changes on the technical end, since I am almost an engineer.

Feel free to phrase away............

 

[Molpet]

I would like to suggest some phrasing changes on the technical end, since I am almost an engineer.

So long as a layperson can follow it.
Sometimes tech speak confuses people who are unfamiliar with it

 

[FowlWitch]

Hi, guys, I hope I'm not derailing. I wanted to ask - has anybody used electric fencing in an area prone to wildfires? I've been reluctant to get an electric fence because the area I live in is so dry! But I'm trying to think of ways to predator proof the yard because I want to put in automatic doors on the coop so the birds can get more free range time. I'm not sure what my best options are.

 

[Howard E]

Dry conditions present two problems. First is the fire danger, which has largely been eliminated by low impedance fencers (which today, is almost all of them).

https://blog.kencove.com/low-impedance-vs-high-impedance/

The second issue is very dry soil, which may not conduct the juice as well as wet soil does, so may reduce the zing of the shock under some conditions. I don't have much experience with desert dry conditions, but if the fence voltage tests out, you know it is working. If in doubt, stand on the same ground the intended target animal does in your bare feet and grab the wire. If it bites, its working.

 

[cmom]

I have a digital voltage tester and every evening when I collect the eggs, I test the wire with it. Once in awhile when I'm out working around the coops I have forgotten to turn off the wire and the birds have touched the wire but it doesn't appear to bother them I believe their feathers work like an insulator.

 

[ChemicalchiCkns]

For dry ground, you can buy a grounding rod and sink it 6 or 8 feet into the ground. But I am not familiar with desert water tables.

 

[ChemicalchiCkns]

[cut]

Background:

Simple electricity is the same as simple plumbing. Electric flow rate, called amperage, is how much electricity is moving through a circuit. Electric pressure, called voltage, is how hard the electricity is being pushed. An electric pump is a battery or a generator.

High amperage is deadly, like having an entire water tower of water strike you, even at low pressure. High voltage with low current is annoying, but much less risky, like having a water pistol squirted at you. Another comparison: at the same water pressure (voltage), a firehose flow is going to injure you much worse than garden hose flow.

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 applies a high voltage (electric pressure) to the metal fencing. 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 two "legs" that comprise the circuit that delivers the electric shock. The electric fencer puts a high voltage (pressure) on 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 electricity flows through the fence, whatever closed the circuit, and the ground. 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 is the missing link, closing 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.
[cut]

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 a power supply, and they are often rated or referenced in "joules". So what is a joule?

The joule (written as a capital J) is a unit of energy. Without physics or metrology butting in, a joule is a watt-second. Your power bill probably has on the back something describing a kilowatt-hour as 1000 W being used in one hour. A joule is one watt being used in one second. In numbers, 1 kWh = 1000 Wh = 3,600,000 J = 3.6 MJ = 3,600 kJ.

For our purposes, a fencer with "this many" joules output is stronger than a fencer with only half that number. Parmak's FAQ and Kencove (link further down) warn against deceptive advertising that makes unlikely assumptions and doesn't tell you. Check the fine print that covers any performance numbers.

(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).

Another measure of the effectiveness is voltage. 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. If you have an odd length of fence, like 17 miles, and buy a 20 mile fencer, it will deliver slightly more than labeled for.

[rest of article unchanged]

 

[cmom]

For dry ground, you can buy a grounding rod and sink it 6 or 8 feet into the ground. But I am not familiar with desert water tables.

It doesn't have to strike water and a 6 ft is good but I think an 8 ft is better. Mine is in the ground with about 6 inches sticking out of the ground so I could clamp on the ground wire.

 

[SarahGfa]

Dry conditions present two problems. First is the fire danger, which has largely been eliminated by low impedance fencers (which today, is almost all of them).

https://blog.kencove.com/low-impedance-vs-high-impedance/

The second issue is very dry soil, which may not conduct the juice as well as wet soil does, so may reduce the zing of the shock under some conditions. I don't have much experience with desert dry conditions, but if the fence voltage tests out, you know it is working. If in doubt, stand on the same ground the intended target animal does in your bare feet and grab the wire. If it bites, its working.

Howard E, first of all thank you for making this post. I have been tweeking my fence over the last couple years to constantly improve it according to your guide.

I live in desert California, and this has been my experience. I have a Parmak 3-joule 30-mile solar charger. During the rainy season (December-April) I get 14,000V off the fence. It's enough to give a bear a heart attack.

In late summer/fall, the voltage drops way off. Right now I am reading about 5000V at the far end of the fence. Based on feedback from my neighbors, 5000V is not enough to stop a hungry coyote. They move into human areas this time of year to find food and water.

I have four ground rods, three feet long. I couldn't get longer rods to go into the rocky dirt we have. I also have ground wire wrapped around the bottoms of the t-posts, so the t-posts act as ground rods too.

This winter I will try to add more ground rods. There are also soil additives you can add to increase conductivity, but EPA may have regulations about where you can do that. It's basicall the equivalent of salting the earth.

 

[Howard E]

Always pleased to see folks using the e-fences. So much to offer for those willing to try it.

Two thoughts come to mind in desert dry conditions. First is the ground rod part of the equation. Only so much you can do.....once you have multiple rods, etc. And as you noted, if the ground the animal is standing upon is bone dry and unable to conduct electricity, animal is not going to get a good shock anyway.

So option B in those conditions is to somewhat mimic what one of the poultry netting options is with the alternating hot and ground wire strands.

With multiple wire fences, make the bottom wire hot and run it close to the ground (inches), then make the 2nd wire a ground wire.........3rd wire hot, 4th wire ground and 5th wire hot. Space the wires so they will try to crawl through the wires, vs under them. That way, they touch a hot and ground wire at the same time.....ground wire tied to fencer's ground and soil, but this way......no need to rely on soil contact at all.

And yet another baiting option........hang a metal soup can (or other small can) from a hot wire......can itself is HOT..........then drop your bait in that. Dry cat food, hamburger, bacon grease, etc. Smellable of choice for your target animal.