Test 1: What is the effect on cattle drinking water from an insulated water trough if an electric fence is within inches of the water tank?

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1 CowContacttm Volume 2004 Issue J March In recent agricultural articles it was proposed that tests done at a cattle watering tank proved that cows were able to detect voltages much lower than those previously claimed by the scientific community. When reading the article it was clear to me that the use of a digital voltmeter to measure the output voltage from an electric fencer was totally incorrect and would produce inaccurate results. I decided to reconstruct the previous test in a manner that was adequate to show the inaccuracies resulting from the use of the wrong instrumentation. Three tests were performed as follows: Test 1: What is the effect on cattle drinking water from an insulated water trough if an electric fence is within inches of the water tank? Test 2: What is the effect on cattle drinking water from an insulated water trough if an electric fence is contacting the water tank but there is no direct contact with the water? Test 3: What is the effect on cattle drinking water from an insulated water trough if the electric fence wire makes contact with the water in the water tank? Basic conditions for the test: The water tank is an AgriMaster 150 gallon plastic livestock tank purchased at Farm and Fleet in Madison, Wisconsin. The electric fencer unit is an International brand Super 100 model. The unit is rated as a 10 mile fencer and has a maximum rated output voltage of 9,000 volts peak. CCVolume 4J 1 3/18/04

2 The electric fence consists of four (4) strands of 17-gauge aluminum fence wire, spaced 10 inches vertically. The earth or ground consists of aluminum sheeting. The cow contact point #1 on the tank is a strip of aluminum foil approximately 1.5 inches wide submersed approximately 4 inches in the water near the top of the tank. The water is home tap water. The water is soft water unless noted. The cow contact point #2 is the earth. This report should be read while observing video clips that document the test facility and test procedures. I have included still frames from the video with this report. Video Clip shows the test area, the electric fence and earth floor. CCVolume 4J 2 3/18/04

3 Video Clip 03 shows a close up of the fence construction. Video Clip 04 shows the insulated water tank. This is also shown above for Clip CCVolume 4J 3 3/18/04

4 Video Clip 05 and 06 show the tank and the cow contact points on the tank. The left rear contact point was not used. CCVolume 4J 4 3/18/04

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6 Video Clip 07 shows the electric fencer unit and how it was connected to the electric fence and the earth. CCVolume 4J 6 3/18/04

7 Video Clip 08 shows the digital voltmeter and this verifies the cow resistor to be 492 ohms. CCVolume 4J 7 3/18/04

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9 Video Clip 09 shows the tank full of water. The foam float is added to identify the water level. CCVolume 4J 9 3/18/04

10 Video Clip 10 shows the proximity of the electric fence to the tank for Test #1. CCVolume 4J 10 3/18/04

11 Video Clip 11 shows the digital voltmeter connected to the tank, the fencer unit is off and with only overhead incandescent lights the background voltage level is millivolts ( volts). When the overhead fluorescent lamps are turned on the background level rises to 0.1 millivolt ( volts). These background levels are insignificant for my test. CCVolume 4J 11 3/18/04

12 Test 1: What is the effect on cattle drinking water from an insulated water trough if an electric fence is within inches of the water tank? This test was performed with tap water. No salt was added. Video Clip 12 shows the voltage across a 500-ohm cow resistor with the fencer operating. The digital voltmeter shows 1 millivolt in the still photo but it fluctuated up to approximately 10 millivolts. The digital voltmeter is not capable of making accurate measurements of short duration impulses. CCVolume 4J 12 3/18/04

13 As you view the oscilloscope output the actual voltage to the cow is as shown below: The peak voltage is in a negative direction and is 22 volts peak (22,000 millivolts). The duration of this peak is approximately 16 microseconds. CCVolume 4J 13 3/18/04

14 This impulse if plotted on the sensitivity chart produced at the University of Wisconsin shows that not even the 5% most sensitive cows in a herd would detect the voltage. This is a 1 cycle biphasic waveform and the upper curve should be referenced. 10,000 V Behavioral response for 5% of the most sensitive cows using sine waves from muzzle to hooves exposure Typ. Fencer 1,000 V 100 V 1 Cycle, Biphasic 1 Cycle, Monophasic Multiple Cycle 5 10 V Test #1 2 1 V (1,000 mv) USDA LOC PSCW LOC 0.1 V Higher Frequency Lower Frequency 0.01 V (10 mv) V (1 mv) 1000 on your AM radio dial 300 Hz (5th Harmonic) 1 millisecond 60 Hz ,000 10,000 Phase Duration (microseconds) = Time between voltage zero crossings Reprinted with permission C. Forster 7/5/00, 6/2003 Important note: Using a digital voltmeter for this test would imply that only 10 millivolts was applied the cow. In reality, the cow was exposed to peak voltages of 22,000 millivolts. CCVolume 4J 14 3/18/04

15 Test 2: What is the effect on cattle drinking water from an insulated water trough if an electric fence is contacting the water tank but there is no direct contact with the water? This test was performed with both tap water and tap water with salt added. Video Clip 13 shows the setup for this test and the results of the test. The electric fence wire is wrapped entirely around the tank to assure maximum contact with the outside of the water tank. The digital voltmeter is set to the Volts range and the cow resistor is 500 ohms. The digital meter fluctuates between and volts (4 to 5 millivolts). CCVolume 4J 15 3/18/04

16 As shown below the actual voltage to the cow would be: The peak voltage is in a positive direction (direction is not significant). The important factor is to select the greatest voltage peak value which is 90 volts peak (99,000 millivolts). The duration of this peak is approximately 19 microseconds. This impulse if plotted on the sensitivity chart produced at the University of Wisconsin shows that the 5% most sensitive cows in a herd would detect the voltage. This is a 1 cycle biphasic waveform and the upper curve should be referenced. CCVolume 4J 16 3/18/04

17 Behavioral response for 5% of the most sensitive cows using sine waves from muzzle to hooves exposure 10,000 V Typ. Fencer 1,000 V 100 V 1 Cycle, Biphasic 1 Cycle, Monophasic Multiple Cycle 5 10 V Test #2 2 1 V (1,000 mv) USDA LOC PSCW LOC 0.1 V Higher Frequency Lower Frequency 0.01 V (10 mv) V (1 mv) 1000 on your AM radio dial 300 Hz (5th Harmonic) 1 millisecond 60 Hz ,000 10,000 Phase Duration (microseconds) = Time between voltage zero crossings Reprinted with permission C. Forster 7/5/00, 6/2003 Please note that the video test clip shows a peak voltage of 80 volts. The above oscilloscope recording was made after adding 1 lb. of salt to the 150 gallons of water to simulate more conductive water conditions. Important note: Using a digital voltmeter for this test would imply that 4 to 5 millivolts was applied to the cow. In reality, the cow was exposed to peak voltages of 80-90,000 millivolts. CCVolume 4J 17 3/18/04

18 Test 3: What is the effect on cattle drinking water from an insulated water trough if the electric fence wire makes contact with the water in the water tank? This test was performed with tap water. No salt was added. Video Clip 14 and 15 show the connections for this test. CCVolume 4J 18 3/18/04

19 Having the electric fence connect directly to the water inside the tank is definitely NOT a good idea. I accidentally put one hand on the earth and contacted the water tank. The shock was definite, not painfull, but impossible to ignore. The voltage that was applied to the cow contact points was too large for my instruments to accept so I used both a 125-ohm and a 250-ohm cow resistor. The typical impedance of a cow s body to these short duration impulses is approximately 100 ohms versus the 500-ohm resistance used in the sensitivity chart. As you will see the recorded values at 125 and 250 ohms correlate well so we can double the voltage recorded across a 250-ohm cow to estimate the actual voltage a 500-ohm cow would experience. The sensitivity chart has been prepared using a 500-ohm cow. This means that the chart will predict behavioral changes before they actually occur in a dairy animal. CCVolume 4J 19 3/18/04

20 Video Clip 16 shows the test performed with a 125-ohm cow resistor (4-500 ohm resistors in parallel). The digital voltmeter is set to the Volts range. The digital meter fluctuates up to 0.35 volts (350 millivolts). CCVolume 4J 20 3/18/04

21 As shown below the actual voltage to the cow would be: The peak voltage is in a positive direction and is almost 300 volts peak (300,000 millivolts). The duration of this peak is approximately 400 microseconds. I will not plot this voltage on the sensitivity chart because it was measured using a 125-ohm cow. Video Clip 17 shows the test performed with a 250-ohm cow resistor (2-500 ohm resistors in parallel). The digital voltmeter is set to the Volts range. The digital meter fluctuates up to 0.69 volts (690 millivolts). CCVolume 4J 21 3/18/04

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23 As shown below the actual voltage to the cow would be: The peak voltage is in a positive direction and is almost 580 volts peak (580,000 millivolts). The duration of this peak is approximately 400 microseconds. I will not plot this voltage on the sensitivity chart because it was measured using a 250-ohm cow. As you can see there is good correlation between the 125 and 250-ohm cow resistor. The 250-ohm resistor experiences approximately twice the voltage peak as the 125-ohm resistor. If I used a 500-ohm cow resistor I would expect to record peak voltages of approximately volts (1,100,000 to 1,200,000 millivolts). CCVolume 4J 23 3/18/04

24 This voltage is shown on the sensitivity chart and would definitely get a reaction from the cow. This is a 1 cycle monophasic waveform and the middle curve should be referenced. 10,000 V Behavioral response for 5% of the most sensitive cows using sine waves from muzzle to hooves exposure Typ. Fencer 1,000 V 100 V 1 Cycle, Biphasic 1 Cycle, Monophasic Multiple Cycle 5 10 V Test #3 2 1 V (1,000 mv) USDA LOC PSCW LOC 0.1 V Higher Frequency Lower Frequency 0.01 V (10 mv) V (1 mv) 1000 on your AM radio dial 300 Hz (5th Harmonic) 1 millisecond 60 Hz ,000 10,000 Phase Duration (microseconds) = Time between voltage zero crossings Reprinted with permission C. Forster 7/5/00, 6/2003 Important note: Using a digital voltmeter for this test would imply that 1400 to 1500 millivolts was applied to the cow. In reality, the cow was exposed to peak voltages of 1,100,000 to 1,400,000 millivolts. CCVolume 4J 24 3/18/04

25 Conclusions: From the above tests I can conclude the following: 1. Using a digital true rms voltmeter to measure impulses from a fencer will result in the user incorrectly assuming an animal responds to very low levels of electricity. The animal actually receives electrical shocks much greater than reported by the digital true rms voltmeter. In my video portion of this report I used a Fluke 189 digital voltmeter. I also used a Radio Shack Model and a Fluke 87. Each of these digital meters will measure the same low values as the Fluke 189. The use of any digital or analog multi-meter will produce incorrect data for this test. 2. Locating a plastic water tank near an electric fence is not a good practice, but if the tank does not contact the fence, the animals may not detect the electricity from the fencer. There are other points to consider. If the water tank causes the animals to crowd and one or more of the animals contacts the electric fence, they may avoid the area. If higher power electric fencers such as 50 mile and 100 mile fencers are used, you can expect more occurrences of voltage affecting the animals. 3. Allowing any metallic or electrically conductive connection between the electric fence wire and the water is clearly not a good idea. The animals will avoid the water tank. ps: Later in a deposition the author of the original water tank test claimed that the tests were performed using a digital meter in the peak hold mode. This would result in a higher reading on the digital meter, but still produce inaccurate data. If you are going to do a scientific experiment you must measure data correctly and to the highest degree of accuracy possible. If you have limitations in equipment, document the tests you performed so others will not misinterpret your data or conclusions. My conclusion remains: The original experiment does not show that animals are sensitive to a lower voltage than previously assumed by the scientific community. CCVolume 4J 25 3/18/04

26 Please see the liability disclaimer at the end of Volume 2001 Issue B. Chuck Forster, P.E. Fluke products can be viewed at Mr. Pulsar can be viewed at CCVolume 4J 26 3/18/04