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: