Livestock Water Tank

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Wayne72

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Condon
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Retired electrician
A rancher has had issues with stock being shocked at the water tank. I was called to see what the fix was. There was 14.8 volts from the water tank to ground (with a new tank heater in the water). The stock would not drink. We drove a ground rod at the source (the shop) and that did not correct the issue. We then replaced an extension cord that was a 12 gauge cord with a 14 gauge cord and that dropped the voltage to near zero.

The rancher then purchased a new 12 gauge cord and plugged it in and the problem came back. He then put the smaller cord back in service and the voltage went back to zero. Up at the source ( a shop with a dirt floor) we tested a tub of water to ground with no extension cord to the tank heater. The voltage to ground at the shop is 14.8 volts from the water to the dirt floor. The service from the shop is an older fuse box and with a tester it shows a good ground at all the receptacles. The extension cord run from the source to the water tanks is about 75 feet.

I am at a loss other than to replace the fuse box at the shop, but it is grounded well and the extension cord gig really is baffling.

Ideas??
 
Does the heater itself have a ground fault? I'd start there, if you got a stray voltage with no extension cord, it surely sounds like the problem. After that, was everything the same when switching between the two cords? Same exact outlet, etc? I'd also be visually checking the entire grounding system- if the shop has fuses, it's likely that half of the grounded receptacles have bootleg grounds; they might show good on a tester, but they're not.
 
Sounds like NEV. View Mike Holt's video on subject might find useful. It might have nothing to do with your installation but coming from POCO, if it is, equapotential bonding would be a fix, similar to protecting a swimming pool.
He also made an interesting video that I saw over summer that he shows in real life how equapotential bonding impacts safety in a pool, he had 120V in a pool that was properly bonded and got into it with no adverse affect, likened it to a bird on a high voltage line or the squirrel running on the wire. I've seen utility working on live lines while bonded to the system in a basket suspended from a 500kv transmission line. Knew it was live as when they bonded saw it draw a large arc as the bond was made.
 
Fred B said:
Sounds like NEV. View Mike Holt's video on subject might find useful. It might have nothing to do with your installation but coming from POCO, if it is, equapotential bonding would be a fix, similar to protecting a swimming pool.
He also made an interesting video that I saw over summer that he shows in real life how equapotential bonding impacts safety in a pool, he had 120V in a pool that was properly bonded and got into it with no adverse affect, likened it to a bird on a high voltage line or the squirrel running on the wire. I've seen utility working on live lines while bonded to the system in a basket suspended from a 500kv transmission line. Knew it was live as when they bonded saw it draw a large arc as the bond was made.
Click to expand...

Mike nails it w/ NEV here

~RJ~
 
Check for bad neutral supplying the shop, or elsewhere in the distribution to the shop. Any rise of volts to ground on the supply neutral will raise all EGC's to ground that are connected downstream from it.
 
The voltage may not be coming from the cord, the cord may actually bonding the tank, and the voltage is from another source through the earth back. Try turning off other circuits that supply power underground. Loads such the well pump that was mentioned by others.
 
Wayne72 said:
1-A rancher has had issues with stock being shocked at the water tank.
2-There was 14.8 volts from the water tank to ground (with a new tank heater in the water).
3-We drove a ground rod at the source (the shop) and that did not correct the issue.
4-replaced an extension cord that was a 12 gauge cord with a 14 gauge cord and that dropped the voltage to near zero.
5-purchased a new 12 gauge cord and plugged it in and the problem came back.
6-then put the smaller cord back in service and the voltage went back to zero.
7-Up at the source ( a shop with a dirt floor) we tested a tub of water to ground with no extension cord to the tank heater. The voltage to ground at the shop is 14.8 volts from the water to the dirt floor. The service from the shop is an older fuse box and with a tester it shows a good ground at all the receptacles. The extension cord run from the source to the water tanks is about 75 feet.
Click to expand...
I have a special interest in these types of knotty problems. As several have replied, use a known load and consider that other things are going on that you or the rancher do not control.

1 You may not feel a shock but women and children may, with this situation. For some reason, cows are sensitive to low current levels. Maybe standing water does it.

2 Buy a 220 ohm, 1 watt and a 390 ohm, 1/2 w resistor from Digikey and measure the voltage across these resistors when connected to the 14.8 v.
You could also buy a 16k resistor to test GFCI fault trip levels.
If you use a hair dryer load, measure the voltage increase as the dryer is switched off, several times.
Along with a formula, these measurements should show the source resistance.

It sometimes helps to have a 4-1/2 digit meter.

3 What must probably be happening for this not to work?

4, 5, 6 This violates physics so something else changed and is changing.

7 I can probably work with a hand drawn equivalent circuit of this setup. Count the ground conduction paths as 25 ohms each.
 
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WasGSOHM said:
I have a special interest in these types of knotty problems. As several have replied, use a known load and consider that other things are going on that you or the rancher do not control.

1 You may not feel a shock but women and children may, with this situation. For some reason, cows are sensitive to low current levels. Maybe standing water does it.

2 Buy a 220 ohm, 1 watt and a 390 ohm, 1/2 w resistor from Digikey and measure the voltage across these resistors when connected to the 14.8 v.
You could also buy a 16k resistor to test GFCI fault trip levels.
If you use a hair dryer load, measure the voltage increase as the dryer is switched off, several times.
Along with a formula, these measurements should show the source resistance.

It sometimes helps to have a 4-1/2 digit meter.

3 What must probably be happening for this not to work?

4, 5, 6 This violates physics so something else changed and is changing.

7 I can probably work with a hand drawn equivalent circuit of this setup. Count the ground conduction paths as 25 ohms each.
Click to expand...
Your analysis has to account for the observations presented. Your dismissal of "4, 5, 6" is the antithesis of the scientific method.
 
gadfly56 said:
Your analysis has to account for the observations presented. Your dismissal of "4, 5, 6" is the antithesis of the scientific method.
Click to expand...

I don’t think he dismissed them. He simply contends that the observed phenomena cannot be explained by the information given.

At least that’s how I read it
 
14 gauge cord has neutral and grounded bonded together in some way.....or maybe neutral and ground reversed on one end????

And yes, what some others are saying......don't be surprised if root cause has nothing to do with heater and circuit to it.
 
hillbilly1 said:
The voltage may not be coming from the cord, the cord may actually bonding the tank, and the voltage is from another source through the earth back. Try turning off other circuits that supply power underground. Loads such the well pump that was mentioned by others.
Click to expand...
The well may be introducing water via the water line. Otherwise it is more likely an intact EGC is bringing voltage rise (to ground) due to voltage drop on the grounded that it is bonded to back at the service - or elsewhere whether that bond is code compliant or not.
 
WasGSOHM said:
I have a special interest in these types of knotty problems. As several have replied, use a known load and consider that other things are going on that you or the rancher do not control.

1 You may not feel a shock but women and children may, with this situation. For some reason, cows are sensitive to low current levels. Maybe standing water does it.

2 Buy a 220 ohm, 1 watt and a 390 ohm, 1/2 w resistor from Digikey and measure the voltage across these resistors when connected to the 14.8 v.
You could also buy a 16k resistor to test GFCI fault trip levels.
If you use a hair dryer load, measure the voltage increase as the dryer is switched off, several times.
Along with a formula, these measurements should show the source resistance.

It sometimes helps to have a 4-1/2 digit meter.

3 What must probably be happening for this not to work?

4, 5, 6 This violates physics so something else changed and is changing.

7 I can probably work with a hand drawn equivalent circuit of this setup. Count the ground conduction paths as 25 ohms each.
Click to expand...
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You would be more sensitive too if you were standing on wet soil, had twice as many feet on that soil, and on top of that could span across more "voltage gradient" in that soil because you have a long "wheel base" compared to critters that stand on two feet.

They can feel those gradients in the soil as they approach and don't like it. Pigs on the other hand are too curious and must check it out. If conditions are lethal you just find them dead next to the water tank, the cows genreally just stay away from it.
 
"4, 5, 6 This violates physics so something else changed and is changing" means finding the root cause(s), which means figuring out all assumptions you are unconsciously making. It's real work. :(

As far as four hooves on the ground, the closest I've come is two bare feet on concrete when I was 12 YO while trying to force an auto radio vibrator into a four prong tube socket of an ancient radio.
It didn't quite fit so I rocked it back and forth.
I figure I got 700 vdc head to foot and a good lesson on grounding. :) And a cardiac stress test to boot.

Besides a hair dryer and a 100w incand bulb, a 100w, 100 ohm rheostat also comes in handy for testing, and the wallwart xformers (not the switcher types) that I kept over the years from discarded electronics are good for low voltage isolated AC and DC sources.

When Wayne72 runs his tests I would add a two probe test as far apart as the cow's wheelbase. A gradient test, so it's now water voltage to ground and hoof to hoof voltage. One test should cross-check the other.
 
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Many farms in my area are older , but with newer equipment.

They were not constructed to art 547 , and in fairness had little need to do so 'back when'...

But over time , they assumed those amenities which qualified them to consider it

the RX? well anecdotally, i've run a lotta #8 bare CU around to anything metallic , even used some old fencing and/or concrete grid under /around equipment

further, create a little distance between any drinking fountain , and the electric fencers , they just don't co-exist.....


~RJ~
 
romex jockey said:
Many farms in my area are older , but with newer equipment.

They were not constructed to art 547 , and in fairness had little need to do so 'back when'...

But over time , they assumed those amenities which qualified them to consider it

the RX? well anecdotally, i've run a lotta #8 bare CU around to anything metallic , even used some old fencing and/or concrete grid under /around equipment

further, create a little distance between any drinking fountain , and the electric fencers , they just don't co-exist.....


~RJ~
Click to expand...

and Do not use the GES in lieu of separate ground rods for your fencer. Keep both well separated.
 
zbang said:
Does the heater itself have a ground fault? I'd start there, if you got a stray voltage with no extension cord, it surely sounds like the problem. After that, was everything the same when switching between the two cords? Same exact outlet, etc? I'd also be visually checking the entire grounding system- if the shop has fuses, it's likely that half of the grounded receptacles have bootleg grounds; they might show good on a tester, but they're not.
Click to expand...
Wayne72 said:
A rancher has had issues with stock being shocked at the water tank. I was called to see what the fix was. There was 14.8 volts from the water tank to ground (with a new tank heater in the water). The stock would not drink. We drove a ground rod at the source (the shop) and that did not correct the issue. We then replaced an extension cord that was a 12 gauge cord with a 14 gauge cord and that dropped the voltage to near zero.

The rancher then purchased a new 12 gauge cord and plugged it in and the problem came back. He then put the smaller cord back in service and the voltage went back to zero. Up at the source ( a shop with a dirt floor) we tested a tub of water to ground with no extension cord to the tank heater. The voltage to ground at the shop is 14.8 volts from the water to the dirt floor. The service from the shop is an older fuse box and with a tester it shows a good ground at all the receptacles. The extension cord run from the source to the water tanks is about 75 feet.

I am at a loss other than to replace the fuse box at the shop, but it is grounded well and the extension cord gig really is baffling.

Ideas??
Click to expand...


Thanks for the help. Here is an update:

If a tester shows a good ground, but it could be a bootleg how does one really know if the ground is up to snuff. Visual? We are going up date the panel in the shop with a breaker box and will run new wires to the outlets and see if that solves the problem. He did call me and said the smaller cord does not have a ground pin. This is the cord that removes the voltage to ground whereas the newer cord with a ground pin brings back the voltage to ground. The water tank is plastic and the heater is new out of the box.
 
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