Electric Fence Help

[Morelia]

To the OP: Help me out here. Are you saying that your fence charger will supply 6A @ 5 KV? If so, you should be dead if you touch it. Mr. Ohm says that is 30KW of power (P= I X E). To supply such power would require 125 A @240V from the mains. I'd hate to pay your electric bill each month. I'd check your measurements again.

Um I'm just reading off the the Smartfix. It gives me 5kV and 3 A. Not an electrician here. Maybe A stands for something else other than Amps?
I did take a reading when I earthed it. A went up to 25. Maybe the smartfix is faulty which is why its giving me problems.

Here it is SmartFix - Remotes and Testers - Gallagher Electric Fence Management Tools

 

[rockinmywaypa]

I don't know what the a actually stands for but the measurements are an indicator of how much current is travelling in a certain direction toward ground. So the lower the value the better. A bunch of drier grass leaning on the fence will have a lower value than the same grass load after a rain, My smartfix generally shows in the range of 6-8, there is a drain there but an out and out short will measure up around 25-35 so I'm willing to live with it.

 

[TCJatko]

I'm guessing that must read milliamps (thousandths of an ampere). Most high-voltage power supplies for CRTs can provide 10 or 15 KV but their current-producing capacity is in milliamps. It bites, but can't kill. (I was an electronics tech in the USAF for a decade or so, back when some test equipment actually had vacuum tubes)

 

[texasjohn]

Morelia, welcome to TBN!!!

I raise cattle, have used electric fences for years. Much experience but not with Gallager chargers and test equipment. Have used similar chargers, however. These chargers, as I understand, run at extremely high voltages AND very high current (amps) BUT the pulse is VERY SHORT, on the order of 3 milliseconds. As you have experienced, humans and cattle can touch the fence, get a full kick from it, and suffer no physical burn or internal damage BECAUSE the pulse is extremely short. The reason for high current is that any weeds or grass touching the fence will drain a small amount of current from the fence, thus, there will be a continuous current drain along the fence as you get further from the charger. Under heavy weed load, the voltage, too, will drop as you get further from the charger. All this is natural, expected. The Gallager will NOT start a grass fire, nor will it even damage the grass touching it.

What you are interested in is the voltage....my experience is that when the voltage drops below about 2000 volts, cattle will begin to disregard the fence. I try to keep it above that, but not always successful with high grass.

The modern electric fence was invented by the Gallager folks. You have state of the art stuff, congratulations.

I, too, often run a mix of barb and smooth electric wire. Works for me.

You will find that in the USA there are many folks who have no experience with the Gallager type of charger, thus the many varied comments so far.

The Gallager will NOT kill cattle, not even burn them. I personally have been accidentally hit by a similar US brand of charger, just a few feet from it while it was running less than 100 yards of fence (charger rated for 100 MILES of smooth, clean fence). Thus, it was HOT. Every muscle in the body tensed up, I rolled over on the ground, lay there for maybe a second then got up and went on. No loss of consciousness or physical burn, just felt like somebody hit me at every point in my body at the same time.

Morelia, I think you are doing well with your fence, its design and the charger/equipment you have chosen. Experience will help you maintain the fence properly, it won't take long to get it all worked out.

My technique of resolving problems is as follows... I have cutoff''s installed at every corner to help isolate the area where a problem has developed.

When voltage is too low (often zero when an actual short exists), go to the middle cutoff and open it. If proper voltage now exists on charged segment, the the problem is in the segment you disconnected. Reconnect the segment and go to cutoff between there and end of the fence. Repeat back and forward until you discover the first segment giving problems (there could be more than one short...you are looking for the first one closest to the charger).

I then walk the fence, looking for the problem. If it is visible, twisted wire, tree on the fence, etc....fix. If problem is elusive, turn the fence on, take a stick or insulated device and walk the fence while banging on the wires to get them to vibrate. You will hear a SNAP where the problem is as the charge arcs to ground, fix.

I suspect that the Gallager tool you have, which also shows current flow, is a significantly better tool than I have. Possibly you can simply walk the fence testing current flow and find the short. To me, a slowly reducing current flow (no sudden drop) would indicate proper operation with some continuous small current loss because of grass/weeds along the fence the further you get from the charger. If the voltage stays up, then it will deter cattle. Sounds like rockinmywaypa understands the SMARTFIX better than I and can explain how to use it best. I found the smartfix manual, in the language of your choice, here.

Says it measures up to 14kV and 40 amps. YES, AMPS!!! Hmm...just read the manual, clever tool, pricy, but may have to get me one for the time I will save me!!

Let us know how it goes...and best wishes..

I'm interested in specifically which charger you are using and the total distance of fence you are charging. Typically, these chargers are used on very long stretches of fence, but work dandy on shorter runs too.

 

[xtn]

It would certainly kill him if he got the whole thing going through him. But if it's grounded out a bit somewhere else, and he's wearing rubber boots and standing on very dry ground, maybe only a small bit of it goes through him.

I'm wondering if perhaps he's using the wrong scale on his multimeter. I don't know anything about electric fences, but I'm guessing the readings he's given are an order of magnitude or two greater than what should be expected, no?

 

[cqaigy2]

Morelia, welcome to TBN!!!

I raise cattle, have used electric fences for years. Much experience but not with Gallager chargers and test equipment. Have used similar chargers, however. These chargers, as I understand, run at extremely high voltages AND very high current (amps) BUT the pulse is VERY SHORT, on the order of 3 milliseconds. As you have experienced, humans and cattle can touch the fence, get a full kick from it, and suffer no physical burn or internal damage BECAUSE the pulse is extremely short. The reason for high current is that any weeds or grass touching the fence will drain a small amount of current from the fence, thus, there will be a continuous current drain along the fence as you get further from the charger. Under heavy weed load, the voltage, too, will drop as you get further from the charger. All this is natural, expected. The Gallager will NOT start a grass fire, nor will it even damage the grass touching it.

What you are interested in is the voltage....my experience is that when the voltage drops below about 2000 volts, cattle will begin to disregard the fence. I try to keep it above that, but not always successful with high grass.

The modern electric fence was invented by the Gallager folks. You have state of the art stuff, congratulations.

I, too, often run a mix of barb and smooth electric wire. Works for me.

You will find that in the USA there are many folks who have no experience with the Gallager type of charger, thus the many varied comments so far.

The Gallager will NOT kill cattle, not even burn them. I personally have been accidentally hit by a similar US brand of charger, just a few feet from it while it was running less than 100 yards of fence (charger rated for 100 MILES of smooth, clean fence). Thus, it was HOT. Every muscle in the body tensed up, I rolled over on the ground, lay there for maybe a second then got up and went on. No loss of consciousness or physical burn, just felt like somebody hit me at every point in my body at the same time.

Morelia, I think you are doing well with your fence, its design and the charger/equipment you have chosen. Experience will help you maintain the fence properly, it won't take long to get it all worked out.

My technique of resolving problems is as follows... I have cutoff''s installed at every corner to help isolate the area where a problem has developed.

When voltage is too low (often zero when an actual short exists), go to the middle cutoff and open it. If proper voltage now exists on charged segment, the the problem is in the segment you disconnected. Reconnect the segment and go to cutoff between there and end of the fence. Repeat back and forward until you discover the first segment giving problems (there could be more than one short...you are looking for the first one closest to the charger).

I then walk the fence, looking for the problem. If it is visible, twisted wire, tree on the fence, etc....fix. If problem is elusive, turn the fence on, take a stick or insulated device and walk the fence while banging on the wires to get them to vibrate. You will hear a SNAP where the problem is as the charge arcs to ground, fix.

I suspect that the Gallager tool you have, which also shows current flow, is a significantly better tool than I have. Possibly you can simply walk the fence testing current flow and find the short. To me, a slowly reducing current flow (no sudden drop) would indicate proper operation with some continuous small current loss because of grass/weeds along the fence the further you get from the charger. If the voltage stays up, then it will deter cattle. Sounds like rockinmywaypa understands the SMARTFIX better than I and can explain how to use it best. I found the smartfix manual, in the language of your choice, here.

Says it measures up to 14kV and 40 amps. YES, AMPS!!!

Let us know how it goes...and best wishes..

I'm interested in specifically which charger you are using and the total distance of fence you are charging. Typically, these chargers are used on very long stretches of fence, but work dandy on shorter runs too.

This post sound correct to me. Extremely short pulses. For cattle its common to have smooth electric with barbed wire because the barbed wire slows them down for the electric to work otherwise cattle will just walk thru the fence. We never used barbed for horses because they can spook and be hurt severely.

 

[Domush]

EDIT: The pulse width of an electric fence is 10 microseconds, not 3 milliseconds, so this warning post doesn't apply. (correction two posts down)

[SNIP]

You can feel 1mA, 10mA will tighten every muscle in your body, 100mA runs the risk of death in a human, especially as the distance of travel increases (your head to foot vs. your leg to foot).

To put it in context, your average GFCI outlet trips at 5mA. Voltage has little bearing beyond the ability to bypass the insulation (skin) and distance vs losses. A 9v battery will kill you if you run leads from your head to your foot under the skin. This is why the tongue test (for those old and dumb enough to have used it) works so well for testing 9v batteries.

An example is this Darwin award.

 

[joshuabardwell]

My technique of resolving problems is as follows... I have cutoff''s installed at every corner to help isolate the area where a problem has developed. I suspect that the Gallager tool you have, which also shows current flow, is a significantly better tool than I have. Possibly you can simply walk the fence testing current flow and find the short.

I concur with this conclusion. If you have a fence tester that measures both volts and amps, and that will also show direction of current flow (the one I have is made by SpeedRite, for example), then I don't think you need cutoff switches on your fence. If there is low voltage on the fence and NO current flow, then the problem is usually weeds. If there is low voltage on the fence and significant current flow (say, greater than about 3-5 amps), the problem is a short, and you just follow the direction of current flow until you find the short.

Honestly, if you have an electric fence, I cannot recommend the SpeedRite style tester enough. It's about $120, and the hours you spend walking the line looking for shorts will buy that back in no time. Once, I had a short that I never would have found. My neighbor has a barbed-wire fence that runs parallel with mine along our property line. The bottom wire of their fence had broken in one point and was touching my bottom wire, totally grounding out my fence. Even once the tester told me where the short was, it took me a few minutes to actually locate it. The rusty brown barbed wire was nearly invisible on the ground.

 

[joshuabardwell]

These chargers are not high voltage and high amperage. The high end MR2500, which is a 230V mains unit, only puts out 16 joules at 7.9KV, which is 126.4 milliamps, which is a large number when talking high voltage, but is a FAR cry from multiple, or even a single, amp.

There is something wrong here, though. Please take a look, for example, at this (http://www.valleyvet.com/Library/lib_25533_-Instructions.pdf). It's the manual for the SpeedRite fault finder. It clearly indicates that it detects current over 1 amp, and the examples it gives show a shorted fence with 20-30 amps. I, personally, have used it to measure a current flow of 30 amps when my fence was being shorted directly to ground by a piece of barbed wire fencing that was laying against it.

I think one key difference is that the shorted fence is going straight to ground, whereas an animal being shocked presents resistance. 5 kV produces 30 amps straight into ground. Through the resistance of an animal's body, the current flow is probably MUCH smaller. If I had a carcass handy, I would go lay it against the fence and measure the current flow to test it. Hmm... *eyeballs the chickens suspiciously*

I don't want some yahoo reading this thread and plugging a step up transformer directly into mains to charge a bank of parallel capacitors thinking he'll save a few dollars, then killing himself, his animals and starting a fire the second something touches the line.

Absolutely.

 

[texasjohn]

Certainly, NO ONE should build their own charger....never said they should.

Gallager is top of the line, have been for years, there are other brands with different performance characteristics, purchase what you have available or can afford, but PURCHASE, do not build your own.

The OP says himself he is measuring 5kv on the top wire at 6 amps. The manufacturer of the tester says it will test a max of 40 amps. He himself says he has been shocked by the fence and survived.

I'll let the reader decide for himself if this is both high volts AND amps.....

The net is that purchased fence chargers WILL shock but NOT kill people or animals.

Now, I just purchased a SMART FIX tester, thanks to the OP for bringing this tool to my attention! I anticipate it will significantly reduce my time to resolve fence problems. Cost was $77, free shipping.

Joshuabardwell, very interesting site you have, good write up on how to use fence tester, I could poke around your site for far too long, seems I resemble quite a few of your remarks and experiences!:laughing:

 

[Domush]

I should have verified the pulse width prior to the original calculation.

Doing some reading on modern electric fences, the pulse width is 10 microseconds, not 3 milliseconds, which makes far more sense, and also explains the high amperage rates, as the shorter time span will increase the effective discharge rate.

For comparison, 10 milliseconds is the pulse width of a modern defibrillator (not something you want as a 'warning' device). Which means a fence shock is one thousandth as long.

One of those small error, big difference things which tend to be the difference between cows grazing where they should and a widow having a Darwin plaque on the wall and some pre-cooked meat.

Joshua, you can put that chicken down, now.

 

[texasjohn]

From this Gallager site I get the following info and stand corrected....it's MICROSECOND...my bad, but it's 3, not 10 for the Gallager, and I think we've agreed it WON'T kill cattle/people:

An animal or vegetation touching the fence will close the system causing the power to flow. The resistance of an animal or human body is 500 Ohm maximum. Energy loss can be caused by poor insulators, shorts and vegetation growth on the wires resulting in a drop in voltage. The heavier the vegetation the more powerful the energizer should be in order to scorch through. In extreme cases always use the MBX-series for maximum results.

Absolutely safe
The brief electrical current or shock emitted by an energzer lasts only 0.0003 of a second. Pulses are spaced 1.2 seconds. An electric fence is completely safe, in fact the system is far more animal-friendly than barbed wire that can cause injury if animals come into contact with it.

 

[Morelia]

Thanks for the reply Texasjohn,

I think I have it all under control now. Don't have much voltage drop at all. I have a speedrite charger which is the same type as the Gallagher. It came with the property. These gallagher style chargers are pretty much the only ones we have available here. Mine is rated to 120km(80 miles?). At the moment I have run out 4km worth of electric fence. I should have plenty of power to fence the 300 acres I have.

I will definitely start placing cutoffs to isolate certain parts of the fence. Thanks for the tip.

Everyone else that replied to the thread thanks. Learn't alot about electrics.

cheers

J

 

[texasjohn]

You likely are already aware of this, but I've found this twister tool very handy.

The 8 knot or reef knot described in this manual is used to join two wires.

Best wishes...you are almost there, just need to attach all smooth wires.:dance1::drink:

 

[texasjohn]

SMARTFIX arrived today.

WOW.....after just a few minutes of experimenting with it I am convinced it will cut my fence problem finding time to less than 10% of what it has been.

Get within a foot or so of the fence, the instrument turns on and indicates a hot fence detected.
Only need to put one end of the tester on the fence. No need to put probe in ground or touch two ends of a tester to two wires.
My favorite readout is the Amps display showing direction of current flow, amps flowing and K volts on the fence.
And, it claims to be water resistant.
Obviously, work on fence finding problem while it is active. Fix one problem and know immediately if all problems are fixed or if another remains. No back and forth turning the fence on and off and retesting.

If you do electric fences, this is the most important tool you can have.

Should have bought one much earlier

 

[joshuabardwell]

If you do electric fences, this is the most important tool you can have. Should have bought one much earlier

I heartily concur. If you have any significant amount of electric fence to maintain, a tester that shows kV, amps, and direction of current flow is a must-have. Yes, I know that you can get by with cutout switches and so forth, but the time you will save with a tester will pay for itself in no time.

 

[MotorSeven]

TJ, where did you find a SmartFix for $77 shipped?

 

[texasjohn]

It was on ebay, a "buy it now" price...just looked, don't see it anymore...said they had 1 left when I ordered ...guess I got the last one.....shipping box out in shop...will see if it left with trash ...if not, will post who shipped it...

 

[Redneck in training]

You are missing two zeros. 3 microseconds = 0.000003 sec. 0.0003=0.3 milisecond.

I also have Gallagher low impedance charger on my fence. If I can't find the leak or short right away I wait till dark and then walk the fence. Quite often the the leak is visible as blue light. I got hit once and have to tell you it was very unpleasant. Almost bit my tongue off for some reason.

 

[rockinmywaypa]

Went on a bus trip once with a group looking at farms. After a long drive we arrived late after dark in the guy's barnyard. Immediately the men in the group ran over to pee near a board fence we could see in the darkness away from everybody. The next day in the daylight we could see an offset wire running down the length of it and the most sobering look on our faces.