Daughter got shocked today cleaning the horse auto-water tank..

[bbaumer]

My daughter claimed she was getting shocked today when she was cleaning out the horse's automatic waterer. I told her it was her imagination as I had disconnected the tank heater at least a month ago. She said she knew that and even checked the disconnect in the barn and it was "off".

Went to check it out. Put my hand in the water. Nothing. She put her hand in. Shocked!. Looked at her feet. She was wearing wet flip-flop sandals. Hmmm. Went around to the other side of the barn, at least 100' away and disconnected the fence charger. Came back to the tank. No shock.

Hmmmm. The fence near the waterer is made of wood. I can find no grounds on the high-tensil fence. Hmmm. Turned fence charger back on and took my shoe off and gave it a go. Yep. I could feel it zap me but not too bad. Got to thinking about a few days ago when we had the horses out and watered them out of the rubber tub. They were acting funny. Testing the water and splashing it numerous times before drinking. Didn't think much of it at the time but I know why now.

Anyhow, disconnected the neutral and ground wires (hot already disconnected at the switch but I also opened the breaker at the panel). Tried the waterer again. No more shock.

Arrrrgh. Not sure where the problem is yet. The water heater is powered through a GFI recep in the barn so I would think if the neutral was skinned it would have tripped when the heater was on but it did not. Gonna be kind of an ordeal to lift the waterer and check the terminations underneath.

Any ideas?

 

[tom baker]

The electric shock threshold is slightly over 1 mA for men, less for women. The GFCI, if working, trips from 4-6 mA.

 

[Rockyd]

Lots of total accumulation potential available. This probably doesn't apply to your case, but offers some diversity in the brainstorming aspect. Click here for links that all electricians should consider when the problem becomes "funky".

 

[charlietuna]

Sounds like a POSSIBLE POLARITY BACKFEED problem. I bet the horses weren't drinking too much water.....

 

[bbaumer]

Just to be clear, the shock is most definitely from the fence charger. It pulses about once per second and you can feel the pulse. No shock. Shock. No shock. Shock. etc.

Just having a hard time figuring out how this is happening. I don't think it is the fence itself since the waterer is next to the wood fence in the corral and several feet away from any high tensile fence, on which there are no grounds.

Just for grins I "grounded" the water with a piece of #8 bare solid copper. Pushed it into the ground maybe 8" and dunked the other end into the tank. This GREATLY increased the intensity of the shock.

The fence charger is grounded to the service grounding electrode conductor 100' away from the water tank. The tank heater also has a ground wire going back to the same service.

 

[ericsherman37]

Just for grins I "grounded" the water with a piece of #8 bare solid copper. Pushed it into the ground maybe 8" and dunked the other end into the tank. This GREATLY increased the intensity of the shock.

Do the horses appreciate your "hands-on" method of testing shock intensity?

 

[benaround]

This exact problem has been on this Forum 2-3 times that I know of, I do not remember

if or how it got solved, it's not that uncommon for some reason. I'll see if I can find the posts.

 

[benaround]

So, is the fence circuit, 1 wire to fence and 1 wire to grounding electrode? If that is so,

I can see a problem.

 

[iaov]

Yeah. First, what the hell are you doing checking a possible shock hazzard by touching it!!:-?This should be checked by a proffesional with a meter!

 

[LarryFine]

It sounds like the fence charger's output is leaking to earth through all of the fence posts and any and all other leakage pathways, possibly including capacitance.

Remember, too, that the charger's output is a high voltage between terminals. Grounding one can cause the earth's voltage to rise around that grounding point.

 

[quogueelectric]

I think the fence is tracking to te better ground at the waterer. Do you have it on insulators at the wooden posts??

 

[whillis]

The fence charger is grounded to the service grounding electrode conductor 100' away from the water tank. The tank heater also has a ground wire going back to the same service.

What you've described is leakage from the fence flowing from the wet ground through the horse, into the water in the trough, then back to the charger through the heater ground or water supply piping. A quick and dirty fix is to scrape 6" of soil off of the area around the trough and lay down a section of concrete reinforcing mesh that's tied solidly to the building ground rod. Once the mesh is covered with dirt it creates an equipotential plane around the water trough and prevents the horses from getting zapped.

The NEC should have specific requirements around grounding and bonding in areas housing livestock, especially dairy barns. Might be worth looking there for some other ideas to mitigate the problem.

 

[bbaumer]

Yeah. First, what the hell are you doing checking a possible shock hazzard by touching it!!:-?This should be checked by a proffesional with a meter!

Never really considered the "danger" of a fence charger. Since I've lived around livestock and hot fences for my whole life (40 years), and been zapped more times than I can remember plus never heard of a fatality from a fence charger, including livestock, I don't think I am taking much of a risk.

Like I said, I made sure the actual feed to the water tank heater was disconnected prior to testing.

 

[bbaumer]

What you've described is leakage from the fence flowing from the wet ground through the horse, into the water in the trough, then back to the charger through the heater ground or water supply piping. A quick and dirty fix is to scrape 6" of soil off of the area around the trough and lay down a section of concrete reinforcing mesh that's tied solidly to the building ground rod. Once the mesh is covered with dirt it creates an equipotential plane around the water trough and prevents the horses from getting zapped.

The NEC should have specific requirements around grounding and bonding in areas housing livestock, especially dairy barns. Might be worth looking there for some other ideas to mitigate the problem.

The tank itself is on a 15x15 concrete slab with mesh in it. It is NOT however tied back to the barn grounding electrode. I can try that easily enough temporarily but it will be some work to do it permanently as they are roughly 100' apart. Trenching will be involved.

 

[hillbilly1]

Check the fence for faults to ground, weeds, cracked insulators and such. Eliminate this fault and your problem will go away, at least until something comes in contact with the fence again. Drive a full size ground rod at the charger, not one of those short ones they supply at the feed store. This will also make the fence more effective at the farthest points.

 

[JWCELECTRIC]

Are the horses drinking from it regularly?

 

[growler]

I bet the horses weren't drinking too much water.....

Just wait until the SPCA get wind of this. " Man has watering trough electrified to keep horses from drinking".... " More on this horrific incident at 11:00".

 

[charlietuna]

The water container's only electrical path is through the water heater's common conductor. Somewhere the shock "pulse" is leaking(since you've determined it's not full voltage) back to the common conductor. Possibly the fence unit is wired backwords or has an internal problem allowing the shock "pulse" voltage to backfeed on the common back to the water heater. by backfeed, i mean via the nuetral.

 

[Brian Oshman]

The fence charger is grounded to the service grounding electrode conductor 100' away from the water tank. The tank heater also has a ground wire going back to the same service.

This is your problem. You do not use the service grounding electrode for the secondary side of the shock controller. You must use separate grounding electrodes no more that 20 feet from the charger and you will need to install three electrodes at least six foot deep and not more that ten feet from one another.

When installing the grounding electrodes make sure that they are installed no less than fifty feet from any service electrode, water pipe, buried service line, telephone line, etc... If you drive the rods within this area then you create the potential for ground loops and shock hazard. The grounding electrodes are for the return of the high voltage secondary charge, not to ground the primary, that is done with the service electrode through the grounded plug.

The secondary ground side must be isolated from the service ground.

Also, as mentioned, while you are at it, go through and inspect all of the insulators and pass through where the hot wire exits the building to ensure integrity of the insulators but you will need to install three, six foot ground rods isolated from the service grounding electrode as I have explained above.

 

[George Stolz]

I'm on board with getting the charger on it's own ground rod, that makes sense to me.

I'd only install one, right next to the charger, IMO.