Electric fence installation / doesn't work

[Medic24]

Reminds me a a guy I was buying a few sheep from one day, as he was talking about how the local dogs have given him a fit, I grabbed the gate to open it, what he did not get out of his mouth fast enuff ws that he had not only rigged the gate up to the electric fence, but that he was hooked up straight wire from his barn outlet......meaning his house current was pulsing thought the gate! Yikes....it felt like some one had taken a sledge hammer to my arm and shoulder............hurt for days.

Needless to say, I kept my money, he kept his nasty stinking sheep. :cboy:

 

[jerry27150]

todd & msscamp, i am scared of mine also, it is a red snapper. if you touch it will make you feel like your heart is coming out or give you a head ache. used to have a neighbor that would use a high powered fencer that you could nail to wooden posts & he never unhooked it or wore gloves or anything to work on it. he went to a meeting with his brother one time & on the way back he told his brother his electric wire was broken. brother started driveing right by & he says where you going, i am going to go unplug it. guy says stop & i will hook it back together for you. they said he grabbed one end in each hand & you could see his arms jerk every beat of the fencer, but it didn't bother him

 

[Frankie]

Reminds me a a guy I was buying a few sheep from one day, as he was talking about how the local dogs have given him a fit, I grabbed the gate to open it, what he did not get out of his mouth fast enuff ws that he had not only rigged the gate up to the electric fence, but that he was hooked up straight wire from his barn outlet......meaning his house current was pulsing thought the gate! Yikes....it felt like some one had taken a sledge hammer to my arm and shoulder............hurt for days.

Needless to say, I kept my money, he kept his nasty stinking sheep. :cboy:

Hooking those up to direct current is very dangerous. A few years ago, a ten year old kid in my area got tangled up in one and was killed.

 

[Dusty Britches]

Not to steal your thread, but mine is a Gallagher battery power. I have a 12 volt, rechargable battery powering about 300 feet. The battery lasts about 2 weeks, if I'm lucky. Can I buy a simple solor charger for this set up, or do I need something else?

btw - I had that same problem. We only had 1 ground rod. We put in 2 more and presto - worked.

My husband touched the wire when we first hooked it up to test it. He told me to touch it and I quite empathatically said no way. He went on about how it was just a little tingle, but I refused to touch it. The next day, we checked the fence again. He said, come on, touch it. No way, said I and I refused to leave the truck. He went to touch it and it arced to his finger. Ow!! he howled. His hand hurt for hours and I laughed for days! :lol:

 

[dun]

Not to steal your thread, but mine is a Gallagher battery power. I have a 12 volt, rechargable battery powering about 300 feet. The battery lasts about 2 weeks, if I'm lucky. Can I buy a simple solor charger for this set up, or do I need something else?

We have 3 Gallaghers. One is A/Cowered and runs a couple of miles of nece and cross fence with 7500-8000 volts at the far end. The smaller ones are battery powerd, one will even work off of D-cells. That one only puts out around 3500 volts but we only power a 1/4 miles or so with it. The other has a solar panel and runs around 5500-6100 volts, we run a mile or so with it too, works great and the battery will last almost indefinitly if we have sunny days and have the panle pointing in the right direction.
The A/C charger has 6 ground rods but we usually just use an old barb wire fence for the ground on the portables.

dun

 

[jerry27150]

gee dun, why don't you get a good 50 miler red snapper & hook them all together. i run miles & miles on mine & it will still knock your socks off. i don't even use one of your ground rods , i just hook it to my cattle panels with steel posts

 

[Bama]

From a electricians point of view. Earth is earth, dirt is dirt, and ground is ground. Its how you get the connection that counts.Multiple contact points on a corral would work as well as a bob wire fence. The delta ( 3 rods in a triangle ) ground rod system is best. A poor ground connection affects your whole fence. Its like the bull verses the cows on herd genetics. That one bull has as much to do with herd genetics as all the cows put together. Same thing with the ground connection. It affects all of the rest of the fence. One loose ground connection drains the whole fence.

 

[dun]

gee dun, why don't you get a good 50 miler red snapper & hook them all together. i run miles & miles on mine & it will still knock your socks off. i don't even use one of your ground rods , i just hook it to my cattle panels with steel posts

I would hook them all together except that they're seperated by anywhere from 250 feet to half a mile from each other.

dun

 

[dun]

I'd have to vote with the ground rod fault crew. It ain't the voltage that shocks its the amps carried by the voltage. Without proper grounding this will not take place. One of the best things to put on a fence is one of those little flashing lights at the end of the run. You can see it a long way in the dark. Also spray the weeds underneath, it will save you some headaches in the future.

You might want to do a little more research. The last time I checked 1/2 amp is fatal. High voltage burns and shocks but unless it gets across your heart or brain it isn;t normally fatal. That's the reason chargers put out mega volts and very little amperage.

dun

 

[Bama]

Actually 1 tenth of 1 amp across your heart can kill a person. The high voltage is used mainly for transmission. Think of the lines feeding your house. They start out at 161,000 volts, then down to 7200,( in most residential systems, there are exceptions ) then on down to 240. This is split further by tapping in a ground and making it neutral to the two legs. By doing this you can have 240 or 110. BTW people very rarely get shocked by 240, its ususlly one side only which is 110. The resistance of the wires would cause to much of a voltage drop if they didn't use the higher voltages. Also voltage will jump an air gap in 70% humity at about 1 inch per thousand volts. Higher voltage does burn a person if it is capable of carrying the amperage. The current is looking for the shortest path to ground. If its the bottom of your foot and you touch it with your hand the moisture in a persons body will conduct enough to cause a burn at the exit site. Now back to fence chargers. They use a high voltage but are incapable of carrying a high amperage. Yes, they do hurt when touched but its not the voltage its the amperage. Anyone putting 110 volts of household current on a fence or gate is asking for trouble. Normally it would be on a 20 amp breaker. At a couple of miles from the voltage source the voltage drop would be so great that you could grab the wire with very little effect. At 100' and you was grounded pretty good you could get the full potential 20 amps. Another interesting fact is that household current is alternating at 60 cycles per second. Causing muscles to contract. Thats why you hear people say they couldn't turn it loose. Fence charger voltage is done by capacitors which produces a direct current pulsing at about 1 second cycles. ( this varies ) You can PM me if you want more information. Fortunately I know more about this subject than I do cattle as this is the way I have made my living for the last 25 years.

 

[dun]

I'm just trying to get this straight in my head. How many amps does the typical charger put out? Why do testers read in volts and not amps? Can I actaully tell the difference between being zapped by 1ma at 800 volts vs 1ma at 500 amps? I ahven;t had to mess with voltage much other then reqiring buildings or DC stuff in 40 plus years, but I was taught that raising the voltage lowers the amperage. Not arguing just trying to get this straight.

dun

 

[dcara]

1st a word on safety. If for some reason you have to touch a wire you think might be live, do it with the back of your hand or back of your finger. As Bama said, the electrical charge will make muscles contract. So if you touch with the back side your hand or finger naturally pulls away. If you touch with the inside then your hand or finger will grab the wire when the muscle contraction happens and you may not be able to let go.

As far as the physics of it go, it is often said that it is the electrical current that will hurt you. But there has to be enough voltage to push the current through what ever resistance exists. The simple equation that defines this relationship is called Ohms Law and is stated as voltage(v) divided by resistance(r) = current(I). Written I=V/R. So the higher the voltage for a given resistance the higher the current, and the higher the resistance for a given voltage the lower the current. Everyone has seen the Van degraph generators in science class that make your hair stand on end when you touch them, or even a comb with static electricity that attracts your hair from 2 inches away. In these examples there are 10's of thousands of volts at play but the resistance is so high that there is little current to speak of. So then it is really the combination/product of voltage(v) and current(I) refered to as power that will get you. Where power(p) in watts = V*I.

Human skin resistance itself can vary from a few hundred ohms to about 50 thousand ohms (called 50k ohms) depending on moisture content. Generally women call feel slightly lower voltage shocks than men because they typically have more moist skin which has the added benifit of making them nice and soft.javascript:emoticon('')
Smile

Dun - assuming your skin resistance and overall contact resistance (i.e total path resistance) to ground were the same for the 500V and 800V tests then by ohms law the 800 volts would push 60% more current through you vs. the 500V. Hence your body (actually total path) would have to absorb 60% more more power so I think you could feel the differene between 1mA and 1.6mA. Your example though compared the same currents at different voltages (i.e. 500V*1mA=0.5 W vs. 800V at 1mA) which implies a 60% increase in path resistance. None-the-less the total power of 800V@1mA is 60% more than 500V@1mA so I think you would also feel that. Fence chargers are actually rated in terms of power by specifying their voltgage and current (i.e. V*I=P). Some are rated in Joules which is just watts per second. That is 120V*0.1A = 12W = 12J/s = 12000V@1mA.

Someone asked about grass and weeds touching the wire. Yes they will reduce the charge on your fence if they touch it. I've also seen fences that don't work in the morning if there is enough dew on the insulator to give the charge a path to ground through the post it is connected to.

Sorry about the rambling, I just got going.

 

[Chuck]

Voltage is the force that enables current (amps) to flow. Without voltage your amps ain't going anywhere. Raising voltage does reduce amp draw on each conductor- BUT for example, a motor doesn't run cheaper on 240 volts than it does on 120. You don't buy volts or amps from the power company, you buy watts. AmpsXVolts. Raising voltage does allow you to run the same motor with smaller conductors. If you were running everything on the farm and in the house with 120 volts the conductors would have to be much larger to do the same job. We have a problem here with the utility raising the voltage too high in hot weather. Our distribution system is old and will barely meet demand when everybody is running the AC and the like. It lowers the amp draw for them, but it sure is hard on my 460 volt motors at work. It's bad enough that some places have put in buck and boost transformers to even things out. As far as the fence charger goes-it all hurts. :shock:

 

[dcara]

Whoops - I forgot to post this link that has a few definitions.

http://www.ac.wwu.edu/~vawter/PhysicsNe ... leLaw.html

 

[Chuck]

Thanks dcara. I poached that one to my favorites list to look at better later.

 

[dun]

It's probably all achedemic anyway. 500 volts-8000 volts, either one will knock you on your butt.
Even with tall wet grass on a mile of fence the better chargers, I think it has to do with pulse length or something, don;t lose all that much juice at the far end. It doesn;t burn the weeds/grass but it pulses past the stuff. We don;t even bother trying to keep the grass short under the fence anymore. The cows will eat it down eventually and the fence is still hot enough to get you pretty good. I had the ground wire connected to an old barbed wire fence. One foggy morning I reeached between the wire, didn;t touch either one, but the next thing I knew I was sitting a couple of feet away. Shocking, (bad pun)!

dun

 

[Bama]

I'm just trying to get this straight in my head. How many amps does the typical charger put out? Why do testers read in volts and not amps? Can I actaully tell the difference between being zapped by 1ma at 800 volts vs 1ma at 500 amps? I ahven;t had to mess with voltage much other then reqiring buildings or DC stuff in 40 plus years, but I was taught that raising the voltage lowers the amperage. Not arguing just trying to get this straight.

dun

The only question that was not addressed in the above post is why do testers measure in volts instead of amps. To measure voltage is cheap and easy. To measure amps you have to either put the probes in line or a clamp ( transformer ) around the wire. D.C. voltage does not work with a transforemer so the amp clamps get really expensive for it as they require more circuitry. Its all about cost and convenience. Voltage is just easier to measure. It goes on the principle that if you have a voltage you also will have a current.

Think of it as a water system. The wire would be the pipe, pressure would be the current or amps, water would be the voltage. Now think of a long run of 4" pipe with several small leaks along its length. If you have enough water it can overcome these small leaks. But to many of these small leaks and you wont have any water at the end. Grass touching is a small leak. A wet limb is a big leak. The better conductor that is touching the fence is like a bigger hole in the water pipe. The better you are grounded the more "shock" you will feel when you touch it. D.C. ( Direct Currect )voltage does hurt worse than A.C. ( alternating Current ) D.C. ramps up to a level and stays there. A.C. goes from positive to zero to negative to zero to positive 60 time per second. Hence you get a jolting touching A.C. and a one time hard hit that stays there on D.C. Thats why there are designed to pulse. BTW voltage is traveling at about 186,000 miles per second so you have to be quick to turn out the lights and be in bed before the room gets dark. Hope this helps.

 

[jerry27150]

no problem, i'm already jumping toward bed when i hit the switch. good way to explain it :shock:

 

[dcara]

Bama - I've always liked the water pipe analogy. Good idea to mention it. It seem to make a lot more since to people that don't spend alot of time on technical matters of physics. Though, I beleive that the analogy is that the flowing water in the pipe, i.e. the curret, is analogous to electrical current, and the hydrostatic water pressure placed onto the pipe is analogous to the voltage, and the diameter of the pipe is analogous to the resistance of the wire. In fact, the fluid dynamic equation for the actual hydrostatic pressure, flow rate, and pipe diameter is of the exact same form as ohms law for voltage, current, and resistance in electrical circuits.

 

[Bama]

You can look at it several differant ways. More years ago than I care to remember I did a little teaching for a college around here. I explained it like water in a pipe and they would catch on. It beat the heck out of standing up there talking about pathagrams theorem, capacitive reactance, ohm and watts laws, impediance reaction, magnetic flux induction, or other laws and thoerems. I found that if they understood it beforehand all of that theorem stuff would come easier. I also taught hydralics so the fluid movement just came easier. I havn't taught any classes in several years but I still work in the electrical/hydralic/robotic/flunkie field for a major manufacturing company. As I have gotten older and look back on my education I am convenced the most important part is wisdom gained from years of experience. I learned at a early age - don't take those old coots lightly, most of them have forgotten more than the rest of us know. At 41 I ain't quite made it to the old coot status yet. I am the youngest in the department of about 100. I work with some really talented old coots that ain't never had a ounce of college education. They can run circles around some of us educated folks.