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oldgraymare
Dec. 31, 2008, 02:57 PM
I just bought a new electric fence tester (digital voltmeter). My last one had little lights on it that lit up depending on how many watts the fence was putting out, but it's always been difficult to see if those lights are flashing, especially in the daytime, so I opted for a newer digital model.

I got the new one at TSC - brand name Fi-Shock, Inc.. It has a nice display screen on it and is easy to read...BUT it reads from 100 v to 9.9 kv, but doesn't give me any information on how to convert these numbers into watts.

I tried googling this problem, but didn't come across any nice website that has a chart on it for the conversion. So if anyone can understand this stuff...if the volt meter when I press it to my hot tape reads 7.7 (kv???), how many watts is this? When I was pressing the end of the voltmeter to the fence (Horseguard tape), I heard some crackling going on, so I know the tape is hot....just would like to know how hot??!!

CHS
Dec. 31, 2008, 03:12 PM
I have one of my kids touch it. They're not very bright and are always up for a dare. LOL Who can touch it the longest. LOL

JenRose
Dec. 31, 2008, 04:53 PM
I am also interested in this question as I got an electric fence tester for Christmas. :winkgrin:

I know my tape fence is hot enough for my horses but not hot enough for hubby's cattle who often break in to steal the horses' round bale.

I am NOT grabbing the fence anymore. I did it when we installed it and I think my heart is just now getting back into a correct rhythm! OUCH!

CHS - your post cracked me up!

Boomer
Dec. 31, 2008, 05:04 PM
Well... I'm sure I could find a formula for this, but I don't know why you need to convert to watts..

If your fence is putting out 7.7kV (7700 volts) - trust me, it's good and hot. Mine puts out 6.5kV and will knock the mess out of you.

Here's a good article describing what is actually happening with kV / amperage and how much "wow" factor your fence has:

http://www.equisearch.com/horses_care/farm_ranch/fencing/eqkeepcurr354/

Milocalwinnings
Dec. 31, 2008, 05:45 PM
An alternative if you get stuck without an actual tester and don't want to touch the fence yourself: Take a blade of grass, wet one end (or lick it...ya, gross... I know:lol:) and touch the wet end to the wire or tape fence and hold the other end. You'll be able to feel the zap enough to know it's on, but not enough to really get zapped yourself.

On a funny note, a barn I once worked at was owned by a peruvian family and they always had these big festivals. We put up a hot wire barrier infront of the fence and along a pathway we used to lead horses from one pasture to the next so no kids could get in (trust me, the year before we had a parent watch his 2 yr old walk out into the horse pasture into the middle of a herd of horses:eek:). Anyways, we thought the fence was hot but didn't really test it ourselves - and we look over and there are about 7 kids holding onto the fence with both hands, leaning into it, some even had their head on the wire!:eek: Um, ok... so we assumed that the fence wasn't hot. The BO's husband told me to go touch the fence- and since I assumed it wasn't hot I did. WRONG! That sucker was zapping harder than the regular fence! We never did figure out how those kids were standing there with fists clenched around the wire, or their head leaning into it... maybe the zap knocked some sense into them.:lol:

Frank B
Dec. 31, 2008, 05:51 PM
Voltage is the most meaningful reading. If you're reading several thousand volts, you should have plenty of "ouch" in the fence. Let it go at that! :lol:

To determine Watts (W), you'd have to know the internal impedance of the charger (Rc + jXc), the ground resistance (Rg), and the resistance of the object being shocked (Ro). Square the voltage (V), then divide by the sum of these three values.

Thus W=(V)(V)/[(Rc + Rg + Ro) + jXc]

Note that since jXc is an imaginary number, you'll have to use complex algebra. :eek:

Now you know why everyone is happy just knowing the voltage! :yes:

4whitefeet
Dec. 31, 2008, 06:29 PM
The last time I accidentally touched my fence, the neighbor thought I was having an epileptic seizure. :eek: :lol:

I don't know about the voltage on mine, but it's supposed to travel 35 miles without interruption. My horses won't go near it.;)

oldgraymare
Jan. 1, 2009, 06:47 PM
Thanks for all the help everyone. I checked my old fence tester (the one with the lights that lit up that were hard to see) and found that each light represents 1,000 volts. Don't ask me why, but I kept thinking each light represented 1,000 watts!! And since the new one only read out how many volts the fence was putting out, I thought I'd have to convert that to watts! Another silly, senior moment on my part, I guess.

ThrushBuster
Jan. 1, 2009, 07:16 PM
So if anyone can understand this stuff...if the volt meter when I press it to my hot tape reads 7.7 (kv???), how many watts is this? When I was pressing the end of the voltmeter to the fence (Horseguard tape), I heard some crackling going on, so I know the tape is hot....just would like to know how hot??!!

Well, I understand some of this stuff (Engineer by trade); The formula for finding wattage is very simple.

Watts = Volts x Amps

So to determine the "watts", you need first determine the Amperes output by the unit (maximum), and the current draw (being used) when the voltage measurement is taken. So, let's say the voltage measurement of 7.7 (Volts) and the current used to produce this voltage (being drawn) is 5 amperes, the the "watts" would be equal to 38.5 watts of "power".

You will need a Digital Multi-meter to measure the volts and amperes to determine "wattage" output...a simple one from the like of Radio Shack, Lowes or Home Depot will do the trick (don't spend much money; maybe $25 should do it). Hope this helps.

ThrushBuster
Jan. 1, 2009, 07:28 PM
To determine Watts (W), you'd have to know the internal impedance of the charger (Rc + jXc), the ground resistance (Rg), and the resistance of the object being shocked (Ro). Square the voltage (V), then divide by the sum of these three values.

Thus W=(V)(V)/[(Rc + Rg + Ro) + jXc]

Note that since jXc is an imaginary number, you'll have to use complex algebra. :eek:

HUH? This would only apply if you wanted to know the power output measured at the horses shoes! I interpreted the question as to what the power output at the wire (in the tape). Let's not overcomplicate the answer...the resistance of the "mule" would then be dependent on the mass of the horse/pony.
So, in simple terms...WATTS = Volts x Amps (output of the unit, at the tape).

CHS
Jan. 2, 2009, 08:45 AM
Send my boys and their stupid friends to your place to test your whole fenceline for you. I swear they'll do it. Not the brightest colors in the crayon box.

Frank B
Jan. 2, 2009, 10:27 AM
HUH? This would only apply if you wanted to know the power output measured at the horses shoes! I interpreted the question as to what the power output at the wire (in the tape). Let's not overcomplicate the answer...the resistance of the "mule" would then be dependent on the mass of the horse/pony.
So, in simple terms...WATTS = Volts x Amps (output of the unit, at the tape).
Yeah, but to know the Amps, you'd still have to know the resistance, since A=V/Z, where A=Amps, V=Volts, and Z=Ohms, which again would be (Rc + Rg + Ro) + jXc.

Since W = V x A, substituting from the above equation, W = (V)(V)/Z.

I had to do some transliteration, since E is normally used to represent Voltage, I to represent current (Amps), and P to represent Power (Watts).

Incidentally, be careful trying to use normal multi-testers. First of all, very few will survive several thousand volts, and second, because the fence charge is a pulse rather than AC or DC, the reading will not be accurate. You'll need a peak-reading meter, which the fence tester is.

FWIW, I used to do this stuff for a living. :lol:

Fairview Horse Center
Jan. 2, 2009, 07:20 PM
I also prefer the long blade of grass thing. ;) Touch the tip and just slide it up closer to your fingers until you can feel the pulse, closer and you can feel the shock. Stop when you have had enough fun. :lol: :lol: "Almost" always handy tool and very reliable.

hosspuller
Jan. 3, 2009, 12:57 AM
I just bought a new electric fence tester (digital voltmeter). My last one had little lights on it that lit up depending on how many watts the fence was putting out, but it's always been difficult to see if those lights are flashing, especially in the daytime, so I opted for a newer digital model.


I tried googling this problem, but didn't come across any nice website that has a chart on it for the conversion. So if anyone can understand this stuff...if the volt meter when I press it to my hot tape reads 7.7 (kv???), how many watts is this? When I was pressing the end of the voltmeter to the fence (Horseguard tape), I heard some crackling going on, so I know the tape is hot....just would like to know how hot??!!

A digital fence volt meter is good for more than just knowing the fence is hot. It will tell you the relative energy at a given point on the fence. This is nice to know when you've got a short that is lowering the fence energy so the horses are ignoring the wire. You know the fencer is good at 7.7 KV. If the reading is less taken at the same spot, you now have something draining energy from your fence. Starting from the spot move along the fence taking readings. As the reading get lower, you're getting closer to the short.


PS ... you wouldn't want anything near a watt of energy on your fence. hand to torso to leg to foot to ground...
Ventricular fibrillation
A low-voltage (110 to 220 V), 50 or 60-Hz AC current through the chest for a fraction of a second may induce ventricular fibrillation (http://en.wikipedia.org/wiki/Ventricular_fibrillation) at currents as low as 60 mA. With DC, 300 to 500 mA is required. If the current has a direct pathway to the heart (e.g., via a cardiac catheter (http://en.wikipedia.org/w/index.php?title=Cardiac_catheter&action=edit&redlink=1) or other kind of electrode (http://en.wikipedia.org/wiki/Electrode)), a much lower current of less than 1 mA, (AC or DC) can cause fibrillation. Fibrillations are usually lethal because all the heart muscle cells move independently. Above 200 mA, muscle contractions are so strong that the heart muscles cannot move at all.

Mudroom
Jan. 5, 2009, 10:39 AM
and we look over and there are about 7 kids holding onto the fence with both hands, leaning into it, some even had their head on the wire!:eek: Um, ok... .....We never did figure out how those kids were standing there with fists clenched around the wire,

the answer is probably that they were wearing rubber tennis shoes and did not have a good ground so the juice didn't flow through their bodies.