Stray Voltage

[Electriceel]

Got a nearby large dairy facility claiming stray voltage but not sure who to blame of course the 1st is the provider.
Can someone give me some basics and proper procedures to verify what is happening?
FYI we are not the provider it is a neighboring Co-Op

[Highplains Drifter]

Stray Voltage is the extraneous voltage that is generated on grounded surfaces when current flows through the resistance of a ground path. The most fundamental requirement in controlling stray voltage is to rigorously maintain the distinction between Ground and Neutral (the grounded conductor). The Neutral wire is a conductor that provides the return path from the load back to the power source. The neutral has White insulation and is grounded only once at the service entrance. The neutral wire is a conductor and must never be grounded at a second place in the system. If it is grounded a second time, part of the neutral current will flow through the building structure and will cause stray voltage. Maintaining the distinction between neutral and ground will eliminate 90% of the stray voltage problems.



Farmers need to select electrical equipment, including lights, that will not generate excessive ground currents. Lighting ballast, electrical motors and auto-transformers are primary sources of leakage current even when they are UL approved and working correctly. All electrical equipment needs to be tested for leakage before it is installed.

The electrical utilities do all of the wrong things relative to stray voltage. They consider ground to be the same as neutral and they connect the primary neutral and the secondary neutral together at their distribution transformers. The neutrals are then connected to water pipes and building structure of the building. All this results in the potential of the building structure and piping being elevated to the voltage level of the utilities neutral conductor. This is the primary cause of stray voltage on a farm. The good news is that this kind of stray voltage can be eliminated quickly and cheaply by insisting that the electrical utility separate the primary and secondary neutrals on your transformer.



Stray Voltage can be caused by either the electrical utility or the on farm wiring or both. Farmers must protect themselves by requiring the utility to isolate their neutrals and by the design of a robust electrical system for their farm.

[climbsomemore]

In Michigan ... we had some trouble when out circuits had undersized neutrals and larger residential loads were added near dairies.

Neutral current will travel along the wire... and will travel down pole bonds into the earth... then go back up polke grounds... eventually most of that return current ends up on the wire and goes back into the sub mat as the engineer intended it too.

That current that circulates near the dairy can end up feeding the stanchions and other metal in contact with the earth in the dairy barn. Water troughs seem to cause the most trouble for the cow... she touches it and feels a few volts...then ceases to drink.... resulting in a loss of milk production. You have to remember ... live stock is barefoot, and with 4 feet they have a lot more contact and greater potential difference between those feet. A man could touch the same barn equipment and not feel a thing.

Consumers got sued a lot for production loss... most of the time we found improper wiring in the barn... but the courts kept siding with the dairy folks.

On the worse cases... we converted wye feeders back to delta in farm areas. Some individual farms had wye fed transformers re worked with a "split neutral" scheme... we simply "made" a secondary ground at the pole and isolated that ground from any grounded primary on that structure. That reduced the circulating current to an tolerable level for the cows.

We had a full time group of techs and legal people working on dairy cases. It's a big problem in Vermont and Wisconsin also... but Wisconsin courts have usually called for code enforcment and made the farmers correct their grounding and bonding or contruct equal potential planes under their sheds and barns. Consumers paid out $25 million to farmers for losses back in the 80's...before they figured out how to fix the problem as the courts still dont make farms follow the NEC in Michigan

[climbsomemore]

Mi Lineman may be able to get you the pages out of his manual... Consumers had a whole section on how to decide when to split the neutral...how to do it (construction and connection details) and how to conduct a test to see if the split solved the problem.

I'd send it too you.. but I can't find my copy anymore

[Stinger]

Install a stray voltage arrestor on the secondary neutural. 1/2volt of stray voltage will stop a cow from milking. If any hands from Green Mountain Power are on this net, they know what I am talking about, cause i learned about the device from them when I was rebuilding a new line up in Addison VT.

[climbsomemore]

Install a stray voltage arrestor on the secondary neutural. 1/2volt of stray voltage will stop a cow from milking. If any hands from Green Mountain Power are on this net, they know what I am talking about, cause i learned about the device from them when I was rebuilding a new line up in Addison VT.

Did that arrestor connected between the primary ground rod and the ground and rod installed for the secondary?

If it was... that little arrestor ties both grounds together if an over voltage or transient happens near that pole..

From what I gather... Green Mountain and the Vermont companies and Consumers Energy in Michigan are about the only companies that fix "stray voltage" by modifications to their system.

Proper grounding and bonding of all the metal parts in a milking shed is probably more effective

[climbsomemore]

Damned to poor memory

I was someplace in OK the last week or so ... A 3phase line buili right over a tin warehouse building

meant to take a picture and got sidetracked

I don't know how insurace companies break even here (without limited liability the probably would all go broke)

[Highplains Drifter]

Got a nearby large dairy facility claiming stray voltage but not sure who to blame of course the 1st is the provider.
Can someone give me some basics and proper procedures to verify what is happening?
FYI we are not the provider it is a neighboring Co-Op

Electriceel, are you reading this? When one starts a thread they usually respond
once in awhile so others know their time and effort to post a reply is being heard....:rolleyes:

[Trbl639]

Damned to poor memory

I was someplace in OK the last week or so ... A 3phase line buili right over a tin warehouse building

meant to take a picture and got sidetracked

I don't know how insurace companies break even here (without limited liability the probably would all go broke)

Seen some of that coming back from colorado thru okie land too, can't remember where it was either, but it wouldn't fly around here!!! We were always at least 10ft beside and 10ft above........although in some of the downtown areas I worked at home, you used the bucket to get on top of the building and then the long stick to re-fuse some of the platform banks.........h-structures in the alley with the switches for the banks looking over the damn building!!!

About 10 yrs ago, we relocated some (well a lot) 3 phase to get it farther away from some newer metal buildings, and the customer paid bigtime to do it...they had encroached on the ROW during construction...

[Electriceel]

Thanks for the input, I have not heard any more from them yet and I will respond when they find something out.

[backtrk]

We had a large dairy come online this year and they put in an incredible ground grid to mitigate stray voltage. We also installed isolating transformers to create a separate grounded neutral system on the dairy.

Heres a good USDA document on the subject.

http://www.mrec.org/pubs/ARSpub696/document.pdf

[dadfirst]

Stray Voltage is the extraneous voltage that is generated on grounded surfaces when current flows through the resistance of a ground path. The most fundamental requirement in controlling stray voltage is to rigorously maintain the distinction between Ground and Neutral (the grounded conductor). The Neutral wire is a conductor that provides the return path from the load back to the power source. The neutral has White insulation and is grounded only once at the service entrance. The neutral wire is a conductor and must never be grounded at a second place in the system. If it is grounded a second time, part of the neutral current will flow through the building structure and will cause stray voltage. Maintaining the distinction between neutral and ground will eliminate 90% of the stray voltage problems.



Farmers need to select electrical equipment, including lights, that will not generate excessive ground currents. Lighting ballast, electrical motors and auto-transformers are primary sources of leakage current even when they are UL approved and working correctly. All electrical equipment needs to be tested for leakage before it is installed.

The electrical utilities do all of the wrong things relative to stray voltage. They consider ground to be the same as neutral and they connect the primary neutral and the secondary neutral together at their distribution transformers. The neutrals are then connected to water pipes and building structure of the building. All this results in the potential of the building structure and piping being elevated to the voltage level of the utilities neutral conductor. This is the primary cause of stray voltage on a farm. The good news is that this kind of stray voltage can be eliminated quickly and cheaply by insisting that the electrical utility separate the primary and secondary neutrals on your transformer.



Stray Voltage can be caused by either the electrical utility or the on farm wiring or both. Farmers must protect themselves by requiring the utility to isolate their neutrals and by the design of a robust electrical system for their farm.


could u explain,@our utility we always bond sec neut to pri neut,cant really think of any other way.also bond x2&h2 to pri neut.this is on a grounded wye system.

[Highplains Drifter]

could u explain,@our utility we always bond sec neut to pri neut,cant really think of any other way.also bond x2&h2 to pri neut.this is on a grounded wye system.



If you are bonding your Primary Neutral to the secondary neutral you have a common neutral, One does not have to do this in fact you do not even have to ground the tank ground and that transformer will work. On your bank pole ground do not connect the primary neutral but only ground the secondary neutral, one connection and nothing else.

[lewy]

If you are bonding your Primary Neutral to the secondary neutral you have a common neutral, One does not have to do this in fact you do not even have to ground the tank ground and that transformer will work. On your bank pole ground do not connect the primary neutral but only ground the secondary neutral, one connection and nothing else.

We are a wye system. Most of our transformers are single bushing. We run H2 right to the system neutral, X2 which has a ground strap we run to the system neutral, we do not run a tap from H2 to X2 unless we are using a 2 bushing transformer. For our case ground we run a separate connection to the down ground which is tapped to the system neutral. for our 3 phase banks the only difference is we tap all of our X2s together & run 1 lead down to the system neutral. I know the transformer will work if we only grounded our secondary neutral (on a single bushing transformer) because 1 end of the primary winding is attached to the tank, but we like some redundancy for safety reasons. The same reason you should always run a lead from H2 to X2 & have them both connected to the system neutral on a 2 bushing transformer is for safety reasons only.

[Electriceel]

I have called the electrician involved, supposedly the dairy is going to hire some guru that will increase the milk production guaranteed.

Sounds to me like the best thing is to go thru the entire facility make sure the secondary ground and neutral conductors are not connected anywhere, and since the dairy owns ther transformers to look at changing them to a delta primary connection if they are not that way allready.

[kctech]

Got a nearby large dairy facility claiming stray voltage but not sure who to blame of course the 1st is the provider.
Can someone give me some basics and proper procedures to verify what is happening?
FYI we are not the provider it is a neighboring Co-Op


I specialize in stray voltage (more appropriately leakage current) detection and mitigation in agricultural facilities. Of all the farms we have inspected in North America a great deal have sub standard wiring, multiple neutral to ground bonds and medium frequency generating equipment (think VFDs and fence controllers) than off-farm problems.

Many companies attempt to detect "voltage" in animal contact areas: free stall, parlor, etc... The fact is that current leaked to the grounding network is present in all grounded machines and buildings not just specific areas. These currents can also be conducted to other structures by way of metallic water lines, gas lines, telephone drops, etc...

I hope this answers your question. If not, let me know and I'll be happy to clarify.

kct

[PSE Lineman]

Google "neutral isolator". Thats what the engineers came up with for dairy farms up here in PSE territory. You have a wye xfmr bank or single phase xfmr. All primary grounds are isolated from the secondary grounds with a second ground rod, 6 feet from the pole, and the straps taken off the tanks. From the secondary ground bushing, the wire goes to one side of the isolator and a seperate ground rod to the svc neut. The primary ground goes to the other side of the isolator and all other neut. connections. Neither touch each other. We even hang a seperate clivis to hang the o/h svc on so the bails don't touch the pri neut. The company lost a lawsuit a few years ago and now freak out when, during a storm when we have out of town crews, one shows up on the dock and they ask where it came from and nobody knows.
One more thing, the engineers tell me that circuit imbalance causes more neutral current thus more stray voltage. They used to put up load loggers and then read them and try to balance the circuits. Not for years now and lots of neut current these days.

[Electriceel]

From the elctrician involved, what is recommended is
1. Go over entire system make sure there are no grounds and neutrals tied together.
2. All 277 volt lighting needs to be 120 volt.
3. Install isolation xfmers on all motors, install soft starts on all motors.
4. All secondaries need to be overhead and be a 5 wire system(3phase).
5. Electric provider install the primary overhead from the main road into this facility(approx. 1/2 mile)

[Highplains Drifter]

From the elctrician involved, what is recommended is
1. Go over entire system make sure there are no grounds and neutrals tied together.
2. All 277 volt lighting needs to be 120 volt.
3. Install isolation xfmers on all motors, install soft starts on all motors.
4. All secondaries need to be overhead and be a 5 wire system(3phase).
5. Electric provider install the primary overhead from the main road into this facility(approx. 1/2 mile)

Great, glad you got it and you can't beat on the job knowledge.

[CPOPE]

22 December 2010 Last updated at 08:06 ET
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Electrocuted dog's Galashiels owner describes ordeal
Ben the dog Ben was electrocuted while being taken for a walk in Galashiels nearly two weeks ago

The owner of a dog electrocuted on a Borders street has spoken about the "horrible" incident in which it died.

David Adam was walking his lurcher-collie cross Ben in Galashiels on 11 December when the incident occurred.

He said the dog had been "one of a kind" and would be "sadly missed".

Investigations are continuing into the cause of the death on the town's High Street. Scottish Power said the power supply in the area had been isolated and posed no public safety risk.

Mr Adam was walking his dog through the town on a Sunday afternoon when it suddenly dropped to the ground and started yelping and shaking.

He said: "It was horrible.

"Ben was trying to drag himself away from the pavement, and he was crying and shaking.
Continue reading the main story
“Start Quote

We'd like to reassure people that the power supply in the area has been isolated and poses no risk to public safety”

End Quote Scottish Power

"He ended up on his side, and when I put my hand on him I could feel his heart going like a train."

Mr Adam called his parents to come to see what was wrong but by the time they got there Ben had already died.

"We took him up to the vet and they confirmed that he had passed away, and said that he showed all the symptoms of being electrocuted," he said.

"Ben was a one of a kind dog.

"He was very loyal and friendly, he had lots of friends round the town and was well-known - he'll be sadly missed."

His family want to know the reasons behind Ben's death to prevent a similar incident happening again.

His father said: "As upsetting as this was, this is not just about what happened to Ben - what if a child had tripped and put their hands down?

"Whoever is responsible needs to do whatever it takes to make the area safe and make sure this can't happen again.

"Appropriate action must be taken by whoever is responsible."

Scottish Power said inquiries were ongoing although they are believed to centre on a faulty downpipe from a building leading to the town centre pavement.

A spokesperson said: "This incident is under investigation and we are checking infrastructure to see what happened.

"We'd like to reassure people that the power supply in the area has been isolated and poses no risk to public safety

[CPOPE]

Wilmington woman electrocuted while walking on sidewalk.
Posted Dec 28, 2010 @ 11:13 AM
Last update Dec 28, 2010 @ 12:12 PM


Prices Corner, Del. — A 37-year-old Wilmington woman was hospitalized Monday evening after she was shocked while stepping on a metal grate on Centerville Road.

According to police, the woman and her 14-year-old son were walking on the sidewalk underneath the 141 overpass when she stepped on the grate, exposing a live electrical wire underneath it. The woman was electrocuted and knocked to the ground by the charge, police said. She was able to call 911 on her cell phone and was transported to Christiana Hospital where she was being treated for injuries police say were not life threatening.

Police say the Delaware Department of Transportation made repairs to the area immediately after the 5:45 p.m. incident occurred.