Stray Voltage at horse heated waterer

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Jan

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Horses were shocked when they drank from the waterer. I'm thinking it's stray voltage. I disconnected the Hot,Neutral and Ground wires in the panel that feeds the waterer(This is the only thing on the circuit). I then checked for voltage at the waterer between the Hot and neutral, V=0, the Hot and Gnd, V=0 and the Neutral and Gnd, V=0. I then placed one lead of my meter into the earth and the other on the housing that the water bowl sits on (this is all metal) and it read V=.4. There is a ground rod at the waterer with a solid grounding wire attached to it and it connects to a lug on the metal housing. If I touch one end of my meter to the metal housing and the other to the waterer ground rod the reading is V=0. If I put one end of the meter in the earth any where else and the other to the metal housing my reading is V=.4. Just for kicks I went over to the Utility pole (about 20' away from the waterer), the transformer for the house sits on top of this pole and put 1 probe of my meter in the earth and the other on the Grounding wire that comes down the pole to a ground rod and the reading was V=.4.
1. What can I do to correct this problem so the horses can drink from the waterer with getting shocked?
2. Are there additional tests I can perform to help me troubleshoot this problem.
Thanks Jan
 
Fix the waterer or the cable leading to it.

Where's your GFCI for the waterer? Where's you equipotential plane? I generally use a megger to check such things.
 
I just read that you have a lug on the waterer bowl attached to a ground rod. What good do you think that is doing you? I offer this... none.
 
I would check the house for a possible loose or open service neutral also. You could have a trickle of neutral current flowing in the earth (Kirchoff's law), and the horses are feeling this due to that goofy ground rod connected right to the fountain's bowl.
 
Isn't the ground rod on the waterer a good idea since it sounds like it and the trough are metal? Wouldn't it act like a (small) equipotential grid? Since the horse will have its feet on the ground and its mouth in the water, if the water tub was isolated from local earth yet there was a large difference between the waterer earth and the service ground, a shock could be possbile. I would expect more of a potential difference between 50' of dirt than 6' of dirt.

Sticking a meter between any two points in the ground is going to show a voltage. Not much you can do about that.

I'd put a GFCI on the waterer circuit and see if that trips. If not, then put a wire mesh in the dirt where the horses stand and bond that to the ground rod (which I hope is bonded to the waterer equipment ground -- if not, do that first). Finally, try switching to a plastic tank and plastic plumbing.
 
suemarkp said:
If not, then put a wire mesh in the dirt where the horses stand and bond that to the ground rod (which I hope is bonded to the waterer equipment ground -- if not, do that first).
Click to expand...
That's what I had in mind there when I questioned the ground rod to the bowl. I suspected that there was no bond to the EGC and it was just from the bowl to the ground rod. Being so close to that utility pole is a big question. Could be lots of things on that pole causing a problem. Leaky lightning arrestor, leaky xfmr, etc.
 
I've only read about stray voltage, and have no direct experience in the field.

suemarkp said:
Isn't the ground rod on the waterer a good idea since it sounds like it and the trough are metal? Wouldn't it act like a (small) equipotential grid?
Click to expand...

As I understand the way ground rods work, the above is true (the water tub would be 'bonded' to the small patch of ground around the ground rod), but essentially of no benefit. The issue is the part about being _small_. If the water tub (and ground rod) were at say 10V, then the soil around the ground rod would also be at 10V. But only 5 feet away the voltage would be down to 2V, meaning that the 'step potential' between the waterer and the soil 5 feet away is 8V. This ground rod might help a kitten, but relative to the size of a horse is essentially useless.

See:
http://www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/Grounding-Part-1-of-12~20041005.php

Note that expanding the 'equipotential grid' may not solve the problem; the waterer and the soil 8 feet around may be bonded and all at the same potential, but the horse may not want to walk over the transition between unbonded and bonded soil. It would depend upon how steep the potential gradient is, how dry the ground is, etc.

Your diagnostics needs to differentiate stray voltage from a fault. Stray voltage may be present with an electrical system that is working perfectly to its design intention, and requires additional design work to overcome. Faults simply need to be fixed.

If this is true stray voltage, then a GFCI will provide no protection, since the source of the voltage is likely the electrical system ground-neutral bond, or the electrical system grounding electrode.

I would suggest the following additional measurements:

1) Reconnect the equipment grounding conductor between the electrical panel and the waterer. Leave the hot and neutral conductor disconnected. Now measure for voltage between the waterer and soil. It may help to have a stubby ground rod to use as your ground electrode.

2) As above, but make the same measurement with the main breaker of the electrical panel off.

3) If this is a subpanel, make the same measurement with the entire electrical service off.

4) With the main power off, place clamp on meter on the service neutral and on the grounding electrode conductor.

-Jon
 
I have seen this twice is the last 20 years. Both times it was the utility pole ground was in sand. I would start by calling the utility co. One of the two I have seen was a home owner getting shocked when they would shower, with the mains at the meter removed , we read voltage from the water line to the metal drain line.It turned out that the water line was a better condutor then the ground rod at the pole"about 40' away". My guess would be in your case the trough is making for a more condutive path then the utility ground. when the utility fixed there grounding it fixed the problem.
 
Troubleshooting GFIs

Troubleshooting GFIs

A friend of mine came to me with a problem. His house has a GFI installed and when it rains the GFI trips. He has checked all the outlets for proper wireing and did not find a problem. How can he isolate where the GFI is being triggered without disconnecting each outlet and waiting for it to rain.
Location of the home is in central Florida.
 
Jan said:
Horses were shocked when they drank from the waterer. I'm thinking it's stray voltage. I disconnected the Hot,Neutral and Ground wires in the panel that feeds the waterer(This is the only thing on the circuit). I then checked for voltage at the waterer between the Hot and neutral, V=0, the Hot and Gnd, V=0 and the Neutral and Gnd, V=0.
Click to expand...

Did you ever check voltages between the waterer and the earth with the circuit connected and on?

.4 volts seems like it would not be too much of a shock, but as a temporary fix, you could put a rubber mat down to insulate the horses hoof from the earth. (Or maybe a wood deck?)
 
hardworkingstiff said:
Did you ever check voltages between the waterer and the earth with the circuit connected and on?

.4 volts seems like it would not be too much of a shock, but as a temporary fix, you could put a rubber mat down to insulate the horses hoof from the earth. (Or maybe a wood deck?)
Click to expand...


How about safety first. To temporarly insulate the horses "DISCONNECT THE POWER" and use a hose to fill the trough. It would be alot safer for everyone. That said, If the rubber mat or wood deck get wet and muddy they will be of little use.It has to be awful to be a thirsty horse around there.
 
.4 volt means a lot to a horse. Another question is it an AC or DC problem. A quick check to determine farm or utility source is to shut all the power off. Monitor the voltage levels as each disconnect is thrown. If you still have the problem with all the power off, call the utility. I do not know the threads but this problem has been discussed and cussed more than ground up or ground down.
 
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