# Fall of potential...why?



## RIVETER (Sep 26, 2009)

There are a lot of posters on this forum who know why a "fall of potential" test should be done. However, there are a lot of "newbies", so to speak, who don't know. Is anyone out there who is eloquent enough to explain the "why" of it?


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## jhall.sparky (Jun 14, 2011)

warning if this is a cheap shot or "attitude adjuster, or make an arse out of you , type of posting i will not play along, if by chance this is a real issue of some one wanting understanding then here goes....... as a "newbie"(i think) my tale of tales...........................

when you drive a rod in the ground you are creating an open path to "EARTH".

one driving a 3/4 " 20' long copper rod in the ground in CHICAGO,IL may not get the same reading as one in HONG KONG , CHINA . the '' earth" has many diverse features and one of those features is PERMEABILITY whether it is a measurement of water, gas, or in this case ELECTRICAL CONDUCTANCE , as this feature we will call "potential" is greatly varying from place to place and in turn season to season,. hence the need to prove a proper ground or "EARTHING".

this is done by preforming a test with parameters and needing a outcome of some sort of reading to make the proof validate its self ..... ONE such test is the fall of potential ( or three-point test ). 


now if inquiring as to WHY one needs proof ........................

that answer can vary from platform to platform but for ease of understanding it will be applied to the ELECTRICAL SYSTEM/S of a structure.

depending on the use of the above information one could be looking to prove a system "worthy" of working with-in its designed or implied parameters.


sorry i went all scientific on you but its your question answered to the best of my ability................. understanding is yours to conquer. 

hope ive help someone or something.......:thumbsup:

J.HALL


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## Roger (Jul 7, 2007)

RIVETER said:


> There are a lot of posters on this forum who know why a "fall of potential" test should be done.


 As far as the voltages we are dealing with, testing a ground rod or rods is simply a manufacturers ploy for selling the test set.  As far as testing a full GES, it can be useful if a performance criteria is relevant such as in telecommunication facilities.




RIVETER said:


> However, there are a lot of "newbies", so to speak, who don't know. Is anyone out there who is eloquent enough to explain the "why" of it?


It is important to realize the reason the NEC requires earthing 



> *(A) Grounded Systems.*
> *(1) Electrical System Grounding.* Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.
> 
> *(2) Grounding of Electrical Equipment.* Normally non–current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.


 
Roger


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## piperunner (Aug 22, 2009)

Well i think he may want to know how it works .

Several methods for measuring the resistance to earth heres the simplest one to explain Volts or the fall of potential .

Two electrodes are place at a distance from the ground rod being tested test rod one and test rod two .


I must add the time of day the weather and the soil can change your reading its only to be done 3 days after a good rain if its too dry its not good if its too wet its not a good test .

And your soil that you have will effect your test sometimes we move the rods around to get the best shot . 

.

A current is passed through the earth between the grounding electrode or meaning your ground rod that you are testing and the test rod lets say test rod two the one furthest from your ground rod under test .

current flows in the soil or earth rod to rod at the same time the test rod closet to your ground rod is call the potential rod meaning volts or voltage rod it measures the voltage drop between the grounding electrode and itself which gives the voltage reading of this circuit through the good old earth .

Fall of potential method is what its called the voltage drop by current flow through the earth from rod to rod .

Years ago before they had digital meters they used a galvanometer when it was nulled by adjusting the knobs on the meter you read your resistance from the knobs that were mark in percents of ohms units .

The frequency of current to measure earth resistance is not just dc its actually 97.5 hertz or cycles this is to keep outside freq of 60 cycles in the earth or near your tester to be canceled out and not effect the test .


So your sending a current into the earth and your measuring the voltage drop !

Which the tester of today changes to a reading in ohms in the old days we adjusted knobs to get ohms on the old meters. 

But lets see if that helps if not ask me a question and ill try my best to answer i dont write or spell good just ask anyone on here but i kinda have a little idea of how things work electrically .

Even if i run pipe all day !


.


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## BBQ (Nov 16, 2010)

RIVETER said:


> There are a lot of posters on this forum who know why a "fall of potential" test should be done. However, there are a lot of "newbies", so to speak, who don't know. Is anyone out there who is eloquent enough to explain the "why" of it?


What are you testing?

The earth or maybe across a breaker?


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## piperunner (Aug 22, 2009)

Well if its fall of potential across a connection same thing your measuring voltage dropped across a metal lug or connection .

With a micro ohm meter its easy today .

Unless you have a homemade one .


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## JD_ (Jul 8, 2011)

RIVETER said:


> explain the "why" of it?


For us the why of ground resistance testing is to make some engineer happy that his delusional spec was met. There really is no reason to care about the resistance of the grounding system.

FOP tests on breakers, contacts and connections is a staple troubleshooting tool though.


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## piperunner (Aug 22, 2009)

Well maybe but theres this thing call touch potential and at higher voltages sometimes its better to have a good earth connection .

Not for the equipment just for you at that special moment .

Depends were your standing next to the equipment if needed.

Just ask the orlando police who ride horseback downtown they know .


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## Jlarson (Jun 28, 2009)

Earth potential rise on low voltage systems. Haha, no.


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## piperunner (Aug 22, 2009)

Well if your grounding is not good well
*Ouc Offers To Buy 2 Horses For Police*

*Money For The Steeds To Replace Two That Were Electrocuted Will Come From A Fee Paid By Hbo.*


March 12, 1997|By Tom Leithauser of The Sentinel Staff
Orlando police could soon be patrolling the streets on two new horses named Reliable and Ozone.
The Orlando Utilities Commission offered Tuesday to give police $3,500 to replace two horses electrocuted in recent days by faulty wiring at a state office building.






Guess what it was .


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> Well if your grounding is not good well
> *Ouc Offers To Buy 2 Horses For Police*
> 
> *Money For The Steeds To Replace Two That Were Electrocuted Will Come From A Fee Paid By Hbo.*
> ...


peanutbutters on the trans?:laughing::laughing::laughing::laughing:


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## JD_ (Jul 8, 2011)

Jlarson said:


> Earth potential rise on low voltage systems. Haha, no.


Yeah there is a difference in importance in earthing on low voltage systems and on medium and high voltage system. And the ground should never be relied on to trip a low voltage OCPD.


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## piperunner (Aug 22, 2009)

JD_ said:


> Yeah there is a difference in importance in earthing on low voltage systems and on medium and high voltage system. And the ground should never be relied on to trip a low voltage OCPD.


Well iam not talking about tripping a breaker .

Were saying touch potential do you know what that is .

And your ground rod can make a difference in the right place .


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## BBQ (Nov 16, 2010)

piperunner said:


> Well iam not talking about tripping a breaker .
> 
> Were saying touch potential do you know what that is .
> 
> And your ground rod can make a difference in the right place .


Ground rods do almost nothing for touch potential below 600 volts.


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## piperunner (Aug 22, 2009)

BBQ said:


> Ground rods do almost nothing for touch potential below 600 volts.



Well tell that to the two horses my friend but its too late there dead .


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## BBQ (Nov 16, 2010)

piperunner said:


> Well tell that to the two horses my friend but its too late there dead .


A proper EGC saves lives, a GEC does almost nothing for person or horse protection at low voltages.

http://www.mikeholt.com/technical.p...od Does Not Reduce Touch Potential (01-25-2K)


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## Jlarson (Jun 28, 2009)

I was just looking for that illustration :laughing:


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## Roger (Jul 7, 2007)

piperunner said:


> Well tell that to the two horses my friend but its too late there dead .


 
As BBQ shows in the illustration above, the problem was not the absence of "Earthing", it was the faulty wiring which obviously included a faulty EGC and how it was bonded or not bonded to conductive parts.

Roger


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## piperunner (Aug 22, 2009)

BBQ said:


> A proper EGC saves lives, a GEC does almost nothing for person or horse protection at low voltages.
> 
> 
> WELL IF YOU TEST IT AND ITS LOWER THAN YOUR RESISTANCE IT WILL SAVE YOU BUT IF ITS NOT A GOOD GROUND YOUR GONE . WOULD I TRUST A GROUND ROD NO BUT IF ITS A GOOD LOW RESISTANCE IT WILL HELP .
> ...












Nice pictures but it depends on the persons resistance and the horses resistance and the place wet or dry and if there bodies at a higher resistance then the rod thats not going to work .Statistics vary widely what maybe considered a dangerous voltage this depends largely on body resistance and other conditions however to limit touch voltage for this situation to say 100 volts the ground resistance for the tower would have to be less than one ohm .

Did you know some folks can handle alot more volts than others and animals well they cant take much .

Were all in different places and do work on low and high voltages so to state one fact like 600 volts is not correct in this field of ours meaning some work at higher voltages and also low voltages.

And if your on a surf board its all over but a surfer can take it we like the juice.


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## BBQ (Nov 16, 2010)

piperunner said:


> Nice pictures but it depends on the persons resistance and the horses resistance and the place wet or dry and if there bodies at a higher resistance then the rod thats not going to work .Statistics vary widely what maybe considered a dangerous voltage this depends largely on body resistance and other conditions however to limit touch voltage for this situation to say 100 volts the ground resistance for the tower would have to be less than one ohm .


You can try to spin it all different ways but electrodes will not reduce step potential to safe levels.


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## piperunner (Aug 22, 2009)

BBQ said:


> You can try to spin it all different ways but electrodes will not reduce step potential to safe levels.



Well i disagree what your saying is because MH has a picture of what he teaches its the bible in any condition of a grounding system.

That is covering a wide area and to some extent it might be but not true in my book thats why we test rods to get the lowest ohm reading .

So the balance between objects can be less of a path a rod is installed for a earth connection a return to the neutral point .

You can stick you test lead into the ground and read voltage off any hot leg ABC to earth there is a connection current would not be high due to the soil resistance of connection do you agree on this.

I see it as if the rod was installed correctly but most dont because code states 25 ohms or less thats there limit .

In this case its not worth installing .



But if its one ohm or less and in some cases lower it can work.

Were pointing out not everyone installs two rods and some folks actually test them and thats alot better than 25 ohms or less in your example that they teach .


I think the resistance of a human generally is higher than one ohm do you agree?

I see it differently then what they teach in school.


Lets twist it around more iam all ears .


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> Well i disagree what your saying is because MH has a picture of what he teaches its the bible in any condition of a grounding system.
> ...


The voltage values in the MH slide come directly from the IEEE "Green Book". Grounding does nothing to improve the safety of a low voltage wiring system. Grounding does not remove voltage, it only provides another path for the current to flow on. This current sets up a step potential around the electrode and actually causes the very problem you are telling us that it prevents.


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## BBQ (Nov 16, 2010)

piperunner said:


> Well i disagree what your saying is because MH has a picture of what he teaches its the bible in any condition of a grounding system.


It has little to do with Mike Holt and a lot to do with basic ohms law.



> That is covering a wide area and to some extent it might be but not true in my book thats why we test rods to get the lowest ohm reading .


You don't test rods to ensure personal protection for systems under 600 volts. I can't comment on systems above that level.

At best they provide lighting protection to some degree.




> So the balance between objects can be less of a path a rod is installed for a earth connection a return to the neutral point .


All you will do is make a second path, and it will not bring the voltage of a line fault down to safe levels.



> You can stick you test lead into the ground and read voltage off any hot leg ABC to earth there is a connection current would not be high due to the soil resistance of connection do you agree on this.


The current would be more than enough to kill.



> I see it as if the rod was installed correctly but most dont because code states 25 ohms or less thats there limit .


Take a rod, put it in the ground, lets say for some reason you get down to 10 ohms.

Now lets put a 120 volt fault into that rod

120 volts / 10 ohms = 12 amps of current.

That current will flow forever because it is well under 15 amps, and the entire time that current is flowing you would have step potential dangers around the rod.





> But if its one ohm or less and in some cases lower it can work.


How often have you gotten a GES to 1 ohm or less.

But still, a 120 volt fault into 1 ohm is 120 amps of current, so this could trip branch circuits, but the time between the fault and the breaker opening you would have dangerous step potential around the rods.



> Were pointing out not everyone installs two rods and some folks actually test them and thats alot better than 25 ohms or less in your example that they teach .


Testing does not make them 'better' and there is no NEC requioment to get under a certain value.

Your GES could have 100 ohms of resitance and it would still be NEC compliant.




> I think the resistance of a human generally is higher than one ohm do you agree?



I don't know, and it really is irelvent.




> I see it differently then what they teach in school.


You might as well say you see it wrong. 




> Lets twist it around more iam all ears .


No you are not, you closed your ears long ago.


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## piperunner (Aug 22, 2009)

Wellllll Iam back!!! BBQ you see we kinda work during the day and my company doesnt let us play on the computer during work time .

If were real good during the day and stay busy my boss gets us snow cones for lunch .

I go to work at 5am and come home at 3 pm for 29 years now same company in the field not the office .

Well we test our ground rods on every job per spec,s and the engineer of the project is a witness to this test .

This is at 480 v 4160 12. kv which ever project were on voltage wise .
Ive never heard that less than 600 volts its not done or needed were did that come from MH .

The record of the ohms is recorded and a document is made by us or on some projects were required to have a separate testing company do our testing it depends on the size of the project .

But ive cad welded many rods with 4/0 cu at 30 foot apart and 30 foot down in a delta over the years .

In florida we get 6 to 8 ohms on one rod at 30 foot down these are copper cad 5/8 rods .


We only use a 3 point tester never use a clamp on and each single rod must get less than 5 ohms or we drive another down .

Our grand total of all rods of that delta after we cad them together is always less than one ohm meaning 1/8 of a ohm or better .

We hit BS & CW & UFFER & GAS each electrical room has a ground bar inside all transformers are attached all panels are attached .

The yards are a matt of 4/0 copper and this is all attached to the lightning protection rods around the building .

So you could say its a good ground .

Yes i dont agree but do i ever agree .


But i have seen 10 amps flowing through a ground rod once with a clamp on amp probe lots of fun .

The ground grid will usually have 0.08 ohms at 5000 amps the touch potential could be up to 400 volts but thats with high voltage work its a lot less with 480 volts .
.
I guess we all have views on how it works but like i said in some conditions a ground rod is a ground point and i dont agree with 25 ohms .


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## Roger (Jul 7, 2007)

piperunner said:


> Wellllll Iam back!!! BBQ you see we kinda work during the day and my company doesnt let us play on the computer during work time .
> 
> If were real good during the day and stay busy my boss gets us snow cones for lunch .
> 
> ...


Piperunner, after all of that it doesn't change the fact that a ground rod or complete GES at low resistance values to earth will do very little or nothing at all for fault clearing or protecting people at below 600 volts.

Testing for earth resistance at these voltages is next to worhtless.



Roger


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## piperunner (Aug 22, 2009)

Roger said:


> Piperunner, after all of that it doesn't change the fact that a ground rod or complete GES at low resistance values to earth will do very little or nothing at all for fault clearing or protecting people at below 600 volts.
> 
> Testing for earth resistance at these voltages is next to worhtless.
> 
> ...



Then why does the electrical engineer on all projects spec the test less than 5 ohms .

If it has nothing to do with a good ground point but just lightning protection why do we need it .

What are ground rods main purpose then waste of money ?

Not even thinking a fault clearing i said that from the start .


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> If it has nothing to do with a good ground point but just lightning protection why do we need it.


 
ohms law my freind....... all unwanted affects will be "EARTHED"..

dont ground anything let lightinig reek havoc on the components as it wants its good for buisness............................................................

further more why are you two bickering about this matter? what does it have to do with the OP?

on the outside looking in,
J.HALL


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## piperunner (Aug 22, 2009)

jhall.sparky said:


> ohms law my freind....... all unwanted affects will be "EARTHED"..
> 
> dont ground anything let lightinig reek havoc on the components as it wants its good for buisness............................................................
> 
> ...




No one asked you for your opinion thanks and we were talking to the OP not you .


Second you dont have a clue to how or what were talking about .




Answer this question since your a expert on grounding think about it my friend before you jump in because i dont agree with the NEC code on grounding ohms 



If the soil resistance is high but the rod resistance is low do you have a better grounding factor or is it a bad ground condition ?

Were having a discussion here my friend just because you chime in and think what ever someone says is the bible because they have 10,000 posts doesnt mean there correct .


Now answer the question ?


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> No one asked you for your opinion thanks and we were talking to the OP not you .
> 
> 
> Second you dont have a clue to how or what were talking about .
> ...


 
ow you got your feelings hurt did you ............. and to answer the question what does it matter wheter the rod is LOW if the ground resistance is HIGH well thereas your answer ............and you are not going to agree with me so set up a model of some sort to prove it!!!!!!!!!!

oh and im not an expert!


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> No one asked you for your opinion thanks and we were talking to the OP not you .
> 
> 
> Second you dont have a clue to how or what were talking about .
> ...


i can be but im not sure your notaition suggest you even know what the heck your saying..............:whistling2:


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## piperunner (Aug 22, 2009)

jhall.sparky said:


> ow you got your feelings hurt did you ............. and to answer the question what does it matter wheter the rod is LOW if the ground resistance is HIGH well thereas your answer ............and you are not going to agree with me so set up a model of some sort to prove it!!!!!!!!!!
> 
> oh and im not an expert!


 No model iam not a google person and the NEC is wrong on 25 ohms for a ground rod .Remember its the minimum protection not the most thats the NEC rules .

Geezz you need to learn how to spell i thought i was bad .


If the rod resistance to earth is low then more current will flow through it dont ya think .

A better conductor to earth .


Less current through you .


If the soil is at a higher resistance to the rod then more current flows through you .

Voltage is low enough at 600 volts so the amps are going to kill you not the volts like one said it doesnt matter we dont need a good grounding system anyway until you need it .


More damage is done with a 25 ohm rod then with a 1 ohm rod .

In some cases it would to me help trip a breaker if it had no other way to find ground if you lost your equipment ground or grounded conductor a better connection to return back to transformer .


I have no feelings .


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> No model iam not a google person and the NEC is wrong on 25 ohms for a ground rod .Remember its the minimum protection not the most thats the NEC rules .
> 
> Geezz you need to learn how to spell i thought i was bad .
> 
> ...


and go where?.....................................................................



and can you PROVE IT!!!!!!!!!!!!!!!!!!!


prove it... prove it....prove it..................... 

also for what its worth (NOT MUCH ) i agree with you on the nec code of 25 ohms being a minimum. 


and what does it matter where i refrence the info from im sure you wrote the books, the google answers,and the wikipedia .............. your so neive!


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## Zog (Apr 15, 2009)

This is funny stuff:laughing::laughing:


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## jhall.sparky (Jun 14, 2011)

Zog said:


> This is funny stuff:laughing::laughing:


these are VERY SERIOUS issues so dont laugh and make jokes , you should be taking notes ............................. :lol::lol::lol::lol::lol::jester:


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## piperunner (Aug 22, 2009)

jhall.sparky said:


> and go where?.....................................................................
> 
> 
> 
> ...



Its common sense Ohms Law .


Cant show you a site or book besides that no one here or any electrician would agree with me on this .

Its the way they see it and read it in the code to me the code is wrong .

They go by what they see or what there told and i dont agree with that sorry but there wrong . 

But there lots electrical engineers that want less ohms since they know more then a forum poster or someone online ill stick with them .

Prove it i already told you what i think so thats pretty much my case if you dont understand me to bad read it over and tell me were iam wrong because so far no one wants to get into detail they just talk about code or what they think .

So explain yourself show me how my way is wrong .

But personally i dont like you !


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> Its common sense Ohms Law .
> 
> 
> Cant show you a site or book besides that no one here or any electrician would agree with me on this .
> ...


ok you asked if a grounded rod grounded in a high resistance earth was a good ground or fault i said fault here's why:

take your _low _resistance pole and mount it in the HIGH resistance atmosphere ( read hold it in the air ) and tell me how you get a good ground ............. common sense HUH?.................

i dont know why you are so reluctant to accept _common sense_ theroies.


REALLY I CANT SPELL????????????? no wonder you cant understand a code...........


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## nitro71 (Sep 17, 2009)

I occasionally see that someone or an animal has received a shock from a light pole. A light pole set on threaded rods set in concrete should be a very good GEC. Yet people and animals still receive shocks. EVERY discussion on why we have a GEC comes down to lightning protection.


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## BBQ (Nov 16, 2010)

piperunner said:


> Its common sense Ohms Law .
> 
> 
> Cant show you a site or book besides that no one here or any electrician would agree with me on this .
> ...



Well you are certainly entertaining. :laughing::laughing: And wrong as well.

Lets get back to the start.

As I understand it you are claiming a better grounding electrode would have saved the horses.

If that is what you are saying you are still mistaken.


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## brian john (Mar 11, 2007)

BBQ said:


> You can try to spin it all different ways but electrodes will not reduce step potential to safe levels.


And not sure how this case was settled, but lawyers and public perception can influence a corporation to settle a case quickly when if they went to court they could very well win.


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## brian john (Mar 11, 2007)

piperunner said:


> It
> 
> But there lots electrical engineers that want less ohms since they know more then a forum poster or someone online ill stick with them .


Most engineers that strive for some exceptionally low ground resistance on a distribution system below 600 VAC are following some previous spec or some false notion of what is required.




> But personally i dont like you !


So you have been proven wrong
You have can’t admit you are not as wise as you think.
So now you resort to pouting like a baby.

OK BIG BOY take your toys and go home, come back later.


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## piperunner (Aug 22, 2009)

Well dont go away yet Brian ,BBQ Roger, Jhall look at photo see the man next to the tower .









Thats touch potential at 1000 volts .


Now ohms law for BBQ and anyone who thinks iam wrong .

This shows a poorly grounded system where ground resistance R is 10 ohms .

A power source impedance Z of 40 ohms a short circuit between the 5000 volt power line and the steel tower would give you 100 amps of short circuit current .


I=E/Z+R 5000V/40+10=100 AMPS 


Touch voltage would be E=IXR 100X10 =1000 VOLTS



To limit the touch voltage for this situation to say ,100 volts the ground resistance for the tower would have to be less than one ohm .

Which is I= 5000V/40+.50= 123 VOLTS 


This means if your ground rod has a good low resistance to earth its better so now explain how iam wrong .

Impedance ohms volts amps it has not changed in years .

Come on lets hear your comments . 


Explain how were wrong and dont back out now iam not finish .


Now this is a book from florida power i guess they dont know anything about grounding and ground rods .


If you test them your doing it the correct .


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> Well dont go away yet Brian ,BBQ Roger, Jhall look at photo see the man next to the tower .
> 
> 
> 
> ...


 
help me understand so you "AGREE"?


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## piperunner (Aug 22, 2009)

jhall.sparky said:


> help me understand so you "AGREE"?



I think florida power is correct and that 25 ohms in the code book is wrong if you test your rods your getting a much lower voltage .




To me its how you test and install your work and this is what you asked for .


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## Roger (Jul 7, 2007)

Piperunner your 5000 + volts in the illustration is not what is being discussed in this thread, all the others (including myself) are talking about 600 volts or less and it has been stated more than once.

A feather falling from the sky and an airplane falling from the sky act differently and can not be thought as equal comparisons.

Roger


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## Zog (Apr 15, 2009)

piperunner said:


> I think florida power is correct and that 25 ohms in the code book is wrong if you test your rods your getting a much lower voltage .
> 
> 
> 
> ...


<25 ohms in FL? in the sand? I think not.


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## piperunner (Aug 22, 2009)

Roger said:


> Piperunner your 5000 + volts in the illustration is not what is being discussed in this thread, all the others (including myself) are talking about 600 volts or less and it has been stated more than once.
> 
> A feather falling from the sky and an airplane falling from the sky act differently and can not be thought as equal comparisons.
> 
> Roger



Well ok now explain whats the difference in detail so i can understand your point from my way of thinking .

Please explain how this is a different system from 600 volts .


Theres 600 volts on the tower line now ?


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## Roger (Jul 7, 2007)

Zog said:


> <25 ohms in FL? in the sand? I think not.


 
Zog, I am pretty sure you and I have both done ground resistance testing in the Tampa Bay area (Bradenton / Sarasota for me) and I never saw single digit readings.

I physically drove an 8' rod 6' into the ground with my bare hand once and finished it with 4 strikes from a 3lb hammer. 

Roger


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## Zog (Apr 15, 2009)

jhall.sparky said:


> these are VERY SERIOUS issues so dont laugh and make jokes , you should be taking notes ............................. :lol::lol::lol::lol::lol::jester:


Oh really?  You think I should BE taking notes on YOUR posts?:laughing:


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## piperunner (Aug 22, 2009)

Roger said:


> Zog, I am pretty sure you and I have both done ground resistance testing in the Tampa Bay area (Bradenton / Sarasota for me) and I never saw single digit readings.
> 
> I physically drove an 8' rod 6' into the ground with my bare hand once and finished it with 4 strikes from a 3lb hammer.
> 
> Roger


Well roger i guess ill put up a video on my next ground rod system because average ohms on our projects are 5 ohms or less every time or we do not pass inspection .

Were not making this up ill will prove it if thats what it takes to show your your wrong in that statement .

Florida we drop 30 foot 5/8 rods three delta 30 foot down and 30 foot apart we test each single rod and get 8 to 6 ohms and when we attach all three it drops below .08 ohms always less than one ohm .

We only do new construction projects does that mean maybe the soil is compacted more so and your in virgin soil thats just not going to give you what we get on our readings .

And were not in sand there is dirt in florida .

That pushing in with your hands is not a good contact with ground earth to rod .

You need to go deeper my friend .


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## Zog (Apr 15, 2009)

Roger said:


> Zog, I am pretty sure you and I have both done ground resistance testing in the Tampa Bay area (Bradenton / Sarasota for me) and I never saw single digit readings.
> 
> I physically drove an 8' rod 6' into the ground with my bare hand once and finished it with 4 strikes from a 3lb hammer.
> 
> Roger


Yep used to live in Bradenton, and my Flordia testing group does ground grid testing there every day, if there was ever a place to drive 2 rods and forget about it Florida would be the place, easy to drive and high readings.


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## Roger (Jul 7, 2007)

piperunner said:


> Well ok now explain whats the difference in detail so i can understand your point from my way of thinking .


Okay, this is where the afore mentioned "Ohms Law" comes into play, use a 25 ohm value with say 120, 277, 480, 600, 4160, and 5000,volts and see what amperage you come up with for each voltage.

Read this thread and take notice of the results Gary saw in his test.

Roger


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## Zog (Apr 15, 2009)

piperunner said:


> Well roger i guess ill put up a video on my next ground rod system because average ohms on our projects are 5 ohms or less every time or we do not pass inspection .
> 
> Were not making this up ill will prove it if thats what it takes to show your your wrong in that statement .
> 
> ...


You do not get .08 ohms, a huge 100' by 100' ground grid system won't get .08 ohms.


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## jhall.sparky (Jun 14, 2011)

Zog said:


> Oh really?  You think I should BE taking notes on YOUR posts?:laughing:


 
oh you too huh?


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## piperunner (Aug 22, 2009)

Zog said:


> You do not get .08 ohms, a huge 100' by 100' ground grid system won't get .08 ohms.



Well zog we think you need to come out to one of our projects because you dont know what we get .

Iwill put up a video of a test three point on site live or my next project ill let you vist when we test our rods like i said we get 5 or less and have many times dropped lower than one ohm with no problem .

Our ground is compacted fill clean dirt not sand it has sand in it but mostly dirt fill clean at 99 .9 compaction we drive the rods in with a air hammer 30 feet to 50 foot at times . That makes a good earth contact not just driving into sand were not on the coast iam in orlando .

What gets me is the responses i get from most on this forum were here telling you what we do and what we get were not making this up the readings are .08 ohms is that not hard to understand .

Just because you test for a living we test every job we do also and for years . 

Nothing high tech about a ground rod test .


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## don_resqcapt19 (Jul 18, 2010)

No matter how good your grounding electrode system is, it does nothing to change the voltage between the energized part and the earth, other than the earth in very close proximity to the grounding electrode. 

Even in high voltage substations with huge grounding electrode systems, they still have to lay a grid of copper below the gravel to reduce the step potential. It is not the connection to earth that reduces the step potential. It is the fact that the conductive grid below the gravel limits the voltage drop across the surface to a 'safe" level. A grounding electrode actually creates the hazardous step potential under fault conditions.

The only change of voltage that a grounding system can make on an energized part is the voltage drop on the metal part caused by the current flow. The current flow to the grounding electrode system will never be large enough to create much of a voltage drop. 

The voltage remains on the part until the fault is cleared and the only way to clear the fault is to have a low impedance path for the fault current back to the source. On voltage systems operating at 600 volts or less, the grounding electrode system will almost never have an impedance low enough to flow enough current to open the OCPD.


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> Well zog we think you need to come out to one of our projects because you dont know what we get .
> 
> Iwill put up a video of a test three point on site live or my next project ill let you vist when we test our rods like i said we get 5 or less and have many times dropped lower than one ohm with no problem .
> 
> ...


i think were being stubborn i can see how more than one *8ohm rod can drop the resistance i understand but im not sure were even arguing the same matter..........................for what its worth( even if you dont like me). i can see you are very experienced and i respect your views.


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## piperunner (Aug 22, 2009)

don_resqcapt19 said:


> No matter how good your grounding electrode system is, it does nothing to change the voltage between the energized part and the earth, other than the earth in very close proximity to the grounding electrode.
> 
> Even in high voltage substations with huge grounding electrode systems, they still have to lay a grid of copper below the gravel to reduce the step potential. It is not the connection to earth that reduces the step potential. It is the fact that the conductive grid below the gravel limits the voltage drop across the surface to a 'safe" level. A grounding electrode actually creates the hazardous step potential under fault conditions.
> 
> ...


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## piperunner (Aug 22, 2009)

jhall.sparky said:


> i think were being stubborn i can see how more than one *8ohm rod can drop the resistance i understand but im not sure were even arguing the same matter..........................for what its worth( even if you dont like me). i can see you are very experienced and i respect your views.



Well i was just joking my friend but i like debates ill take that back no problem .

I just dont take what i read as bible and like to look at **** a different way electrically and would like to see what others think or know and some times i may be wrong who knows .

But i need someone to detail what that is because i just dont see it yet .


I dont like 25 ohms in the code book so why is it 25 ohms ?


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## JohnJ0906 (Jan 22, 2007)

piperunner said:


> I dont like 25 ohms in the code book so why is it 25 ohms ?


That question has been asked on this (and other) forums as long as I have been around, and no one has been able to answer that.


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## piperunner (Aug 22, 2009)

JohnJ0906 said:


> That question has been asked on this (and other) forums as long as I have been around, and no one has been able to answer that.



Thats because ? I think if they had a good low resistance on the rod to the earth it would be what worst .

I fail to see what some are pointing out maybe i need to go back to school but .Under a fault condition if current flows into the rod to earth the voltage would drop meaning the touch voltage would be lower not gone completely but lower safer . YES ?NO ? hummm ?answer ? Wrong ? what ? .


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## jhall.sparky (Jun 14, 2011)

piperunner said:


> Well i was just joking my friend but i like debates ill take that back no problem .
> 
> I just dont take what i read as bible and like to look at **** a different way electrically and would like to see what others think or know and some times i may be wrong who knows .
> 
> ...


i think a lot of issues can be hashed out theoretically and am not sure why 25 ohms is accepeted as standard, it is however a low reading none the less, and we havent made it to the first few pages of the NEC and thats why our opinions arent applied. remember EVERYONE thought the world was flat at one time............................... 

but theory and reality mix like oil and water ............. here's why 25 ohms is ok in my book think about a smaller install where me having to have 3 or more ground rods placed 50 feet deep isnt really practical..... not arguing the theory just the practical application............ ive often wondered how hard it is to write the rules that need to be so well rounded?

also its good that you dont use the MINIMUM code as a high point in your installs .for that i have much respect ........:thumbsup:


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> ...
> Well Don your the only one that can actually explain this issue all i get from the others is you cant do that your wrong .
> .
> Now look at my florida power post with photo tell me there wrong or correct whats the difference of a 600 volt system to a high voltage ground system .
> ...


Yes, I am going to tell you that they are wrong. The voltage on the metal tower will be the full line voltage as measured to the earth, other than the earth very close to the grounding electrode. 
As far as a lower impedance, it doesn't really make any difference until the impedance is low enough that there is enough current flow to cause the OCPD to open. The difference between a high or low voltage is really the amount of current that will flow on the grounding electrode. With a high voltage system it is much more likely that there could be enough current flow to open the OCPD.


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## user4818 (Jan 15, 2009)

don_resqcapt19 said:


> On voltage systems operating at 600 volts or less, the grounding electrode system will almost never have an impedance low enough to flow enough current to open the OCPD.


Hypothetical question then - why do premises wiring system engineers have this obsession with creating and testing the elaborate GES that piperunner describes for buildings with >600V wiring systems? Seems to me it would be more beneficial to call it a lightning protection system.


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## JohnJ0906 (Jan 22, 2007)

piperunner said:


> Thats because ? I think if they had a good low resistance on the rod to the earth it would be what worst .
> 
> I fail to see what some are pointing out maybe i need to go back to school but .Under a fault condition if current flows into the rod to earth the voltage would drop meaning the touch voltage would be lower not gone completely but lower safer . YES ?NO ? hummm ?answer ? Wrong ? what ? .


Under a fault condition you don't want current flowing through a ground rod. That is not what it's purpose is. The current should be flowing through an *equipment grounding conductor.* That is the effective ground fault current path.
Earth is not an effective ground fault current path for low voltage systems. See 250.4(A)(5). Not enough current will flow to operate an OCPD.


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## piperunner (Aug 22, 2009)

don_resqcapt19 said:


> Yes, I am going to tell you that they are wrong. The voltage on the metal tower will be the full line voltage as measured to the earth, other than the earth very close to the grounding electrode.
> As far as a lower impedance, it doesn't really make any difference until the impedance is low enough that there is enough current flow to cause the OCPD to open. The difference between a high or low voltage is really the amount of current that will flow on the grounding electrode. With a high voltage system it is much more likely that there could be enough current flow to open the OCPD.



Well don whats the impedance Z for in there book how does that relate to there example if its wrong i guess id better tell Florida power to change there school books .

Tell me what touch voltage they should have in there book ? your saying 5000 volts touch potential that the resistance of earth to ground will not drop it like a series resistor inline with earth or soil resistance .

And a higher voltage would trip out breaker or switch faster then at 600 volts .

Do to the current flow does current move faster at a higher voltage then at a lower voltage ?


I am not there yet go on please


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## JohnJ0906 (Jan 22, 2007)

Peter D said:


> Hypothetical question then - why do premises wiring system engineers have this obsession with creating and testing the elaborate GES that piperunner describes for buildings with >600V wiring systems? Seems to me it would be more beneficial to call it a lightning protection system.


They get paid by copper.org :laughing:


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## user4818 (Jan 15, 2009)

JohnJ0906 said:


> They get paid by copper.org :laughing:


Doh! Why didn't I think of that! :laughing:


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## piperunner (Aug 22, 2009)

Zog said:


> Yep used to live in Bradenton, and my Flordia testing group does ground grid testing there every day, if there was ever a place to drive 2 rods and forget about it Florida would be the place, easy to drive and high readings.



Well in response to you wealth of testing in florida huummm.

In Vero Beach florida i did a new 45 mega watt generator with a GE reheat you know the jet engine type small not a large project this was on the coast and you could not drive a rod into the earth it was coral stone we drilled into the ground or stone and drove 65 foot rods down these were cad weld together meaning each rod to rod .


We also had a matt screen over the yard 4/0 copper 16 inches center to center lots of copper we installed 68 rods in that yard .

Everything was at ground zero you could say this was a exsiting power plant which we added a new reheat system and new generator for Vero .

So ZOG yes we kinda know what a power plant is and a grounding matt .


We also know that ground clamps are not a good connection its a resistance over time it gets to be a higher ohms reading . But hey that will keep your company busy easy work for your group company .

If you install a rod in uncompacted soil condition your asking for a bad reading .

We compact it and get lower results thats a fact .

If you work in yards you know laying a matt under stone which most yards are because the power company needs it for ease of new work and repair of old things .

And its at a higher resistance then dirt alone it has air pockets in it .

Plus mud a water around high voltage is a bad thing thats why they put stone down .

When we install a new clean rod we get better readings but after years its not the same corrosion and water and soil age it so guess what bad readings .


We know how to install a ground rod my friend and a grounding matt and have done a few power plants over the years .

Theres good earth and bad earth but dont ever tell me what readings i get when i test .

You seem to know what we do but i dont know how its funny do you ever read the stuff you post this is not my first barbaque opps spell check .


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## piperunner (Aug 22, 2009)

JohnJ0906 said:


> Under a fault condition you don't want current flowing through a ground rod. That is not what it's purpose is. The current should be flowing through an *equipment grounding conductor.* That is the effective ground fault current path.
> Earth is not an effective ground fault current path for low voltage systems. See 250.4(A)(5). Not enough current will flow to operate an OCPD.


Yes thanks for that we kinda know that what were needing to know is .

Why is the code 25 ohms why do engineers make me have to have less than 5 ohms .


Why does Don say high voltage trips faster then low voltage ?


Why does Zog think we dont get .08 ohms on our ground tester ?


Were talking about touch voltage now and my question is this 

The voltage drop which is the touch voltage because of the resistance of the rod to earth if current goes up voltage must go down .

So if you have a lower ohm system the breaker would trip faster and you would have less touch voltage hummm .

But then you get the response well the ground rods are for only one thing lightning .HUMMM 

How come florida power puts rods down and shows it in there school books and teaches stuff that some say thats wrong .

So florida power has incorrect formulas in there school books and are not teaching good info ill let them know monday .

Does anyone have a clue why do we do different things all engineers are wrong according to some on here.hummm 

Every post is special i just cant wait to see whats next iam not a engineer i never went to school i cant speel oss gee i even spell opps wrong .

Well what is 600 volts to 4160 volts its faster when it trips more speed wise you dont need a ground rod at 600 volts or less .

Give me a break but explain this in detail i will listen i promess !

OOPS Spell check !


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> Well don whats the impedance Z for in there book how does that relate to there example if its wrong i guess id better tell Florida power to change there school books .


That would be a good idea as they are completely wrong.



> Tell me what touch voltage they should have in there book ? your saying 5000 volts touch potential that the resistance of earth to ground will not drop it like a series resistor inline with earth or soil resistance .


Lets look at it this way. What happens to the voltage on the ungrounded conductor when you connect a load between it and the grounded conductor? 
A fault to a grounding electrode is no different...it is only a load. It will do the same thing to the voltage on the ungrounded conductor as any other load. The voltage on the metal structure as measured to the earth will be the full line voltage. 



> And a higher voltage would trip out breaker or switch faster then at 600 volts .


The only difference is based on ohms law. The higher voltage will cause more current to flow though the grounding electrode than will a lower voltage through the same electrode. With either, if the current is high enough, the OCPD will open. This is much more likely to happen on the higher voltage system.



> Do to the current flow does current move faster at a higher voltage then at a lower voltage ?


No.


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## jhall.sparky (Jun 14, 2011)

:wallbash::w00t::wacko::nuke::nuke::nuke:........ come on!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> ...
> 
> Why does Zog think we dont get .08 ohms on our ground tester ?
> ...


Exactly what ground resistance tester were you using and exactly what were you testing?


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## piperunner (Aug 22, 2009)

What is wrong with there example they are saying its 1000 volts not full voltage i see ohms wire resistance do to a long distance from tower to a point .

There formula is ohms law if you have a connection from earth that has rod resistance from earths soil that resistance plus Z of AC wire and earths resistance through rod ,

I see it limiting the current and only dropping a voltage for that current not the full current yes under a direct line to line fault its to me a full current, but passing into a resistance i dont see full voltage for touch voltage .

That return point is a long way from that ground rod i see it the way they have it .

We see it this way dropping a voltage across that load due to current flowing through it at a lower current due to resistance of load like at 600 volts lower current due to lower voltage .

Meaning you get shocked but not by the full voltage but a lower voltage due to human & rod & earth resistance were your at to the ground rod from that point .

I do see step voltage this way from the rod to a point ohms change from that point i see less amps flowing through a human and i can see resistance going up .

I also see ohms law if resistance gos up meaning the earths resistance from that rod point to person being shocked there saying step voltage increases a distance further away from that rod that is theory ohms law R gos up due to distance so at that same current yes more voltage will be dropped.


Which to me would effect voltage .




But i dont see current staying the same .


When they do a current fault study on feeders they assign a ohm figure to the feeder by length of run and by type of conduit pvc or metal underground or overhead could this be what Z impedance is in there example .

Lets look at it this way. What happens to the voltage on the ungrounded conductor when you connect a load between it and the grounded conductor? 
A fault to a grounding electrode is no different...it is only a load. It will do the same thing to the voltage on the ungrounded conductor as any other load. The voltage on the metal structure as measured to the earth will be the full line voltage. 

Its passing through a resistance which is dropping voltage across that load .




Full voltage is applied to the load and i see that but i also see a ground or earth connection through rod and a limit on current which would drop a voltage to that load meaning the frame of tower. 


If its a paralleled circuit but i see it as a person grabbing onto a frame as the ground rod point its a new point of contact with its own voltage and current we all dont get shocked in a perfect location as MH shows .

The only difference is based on ohms law. The higher voltage will cause more current to flow though the grounding electrode than will a lower voltage through the same electrode. With either, if the current is high enough, the OCPD will open. This is much more likely to happen on the higher voltage system.

I agree with this yes a higher voltage will let current will pass in the soil better than at 600volts if its dry and not wet if its wet to me it would be the same . 


I agree that current will flow into both high or low systems i dont see it any different way but i see that resistance of earth and ground rod and wire length resistance meaning Z conduit type pvc or rigid under a fault needs to be added into the time it takes to trip .






No.[/quote]


Please understand were interested in this the why of it as a elecrician which i have no formal schooling i want to know how it works but i will input also what i feel your ok Don i like your post at least you will explain your side .


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## BBQ (Nov 16, 2010)

piperunner said:


> Please understand were interested in this the why of it as a elecrician which i have no formal schooling i want to know how it works but i will input also what i feel your ok Don i like your post at least you will explain your side .



It has been explained to you a dozen different ways but you just refuse to take it in.


To bad for you.


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## piperunner (Aug 22, 2009)

BBQ said:


> It has been explained to you a dozen different ways but you just refuse to take it in.
> 
> 
> To bad for you.



Ive yet to see you tell me how my tower touch voltage example is wrong lets see you explain it so maybe you can change what i think and what florida power thinks .

Your input would be great to here in your own words not someones else .


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## Zog (Apr 15, 2009)

don_resqcapt19 said:


> Exactly what ground resistance tester were you using and exactly what were you testing?


Exactly my point, I suspect the test is being done incorrectly, no way you get .08 ohms no matter what your soil conditions are. Piperunner, show me one FOP graph with a plateau at .08 ohms. Expain how you are conducting this test.


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## BBQ (Nov 16, 2010)

piperunner said:


> Ive yet to see you tell me how my tower touch voltage example is wrong lets see you explain it so maybe you can change what i think and what florida power thinks .
> 
> Your input would be great to here in your own words not someones else .


I took the time to do so in post 23, I have no desire to keep wasting my time doing so again.


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> What is wrong with there example they are saying its 1000 volts not full voltage i see ohms wire resistance do to a long distance from tower to a point .
> 
> There formula is ohms law if you have a connection from earth that has rod resistance from earths soil that resistance plus Z of AC wire and earths resistance through rod ,
> 
> I see it limiting the current and only dropping a voltage for that current not the full current yes under a direct line to line fault its to me a full current, but passing into a resistance i dont see full voltage for touch voltage .


So you are telling me that you expect a small load to drop the line voltage to a lower value. The voltage drop on any system is across the load. In the case of a fault to a grounding system the "load" is the earth. There will be voltage dropped across the earth creating the step potential. There will be very very little dropped on the tower itself. The tower will remain and line voltage until the fault is cleared. The is still the same as what happens to the line voltage any time you connect any load. In general the line voltage does not change. 



> That return point is a long way from that ground rod i see it the way they have it .
> 
> We see it this way dropping a voltage across that load due to current flowing through it at a lower current due to resistance of load like at 600 volts lower current due to lower voltage .


Again, with a ground fault the voltage drop is across the earth (load) and not across the energized metal parts.



> Meaning you get shocked but not by the full voltage but a lower voltage due to human & rod & earth resistance were your at to the ground rod from that point.


You get shocked by the voltage between the energized metal parts and the earth you are touching. The closer you are to the grounding electrode the lower this voltage will be. If you are 3 feet away from the grounding electrode you will receive a shock that will be about 85% of the voltage that is on the energized metal part. This is the very reason for the copper grid installed under the gravel in a substation. The grid raises the voltage of the gravel to reduce the step potential. The complete grid and grounding electrode for the substation will be raised to thousands of volts above ground (earth) that is outside the influence of the substation grounding and bonding system. 



> I do see step voltage this way from the rod to a point ohms change from that point i see less amps flowing through a human and i can see resistance going up .


The current through the person is based one the voltage across the person and the impedance of the path through the person.



> I also see ohms law if resistance gos up meaning the earths resistance from that rod point to person being shocked there saying step voltage increases a distance further away from that rod that is theory ohms law R gos up due to distance so at that same current yes more voltage will be dropped.
> 
> 
> Which to me would effect voltage .


Again the load does not really change the line voltage. The earth is the load under ground fault conditions.


> But i dont see current staying the same .


The current for any circuit, including ground faults will be based on the voltage across the load and the impedance of that load.


> Full voltage is applied to the load and i see that but i also see a ground or earth connection through rod and a limit on current which would drop a voltage to that load meaning the frame of tower.


But the voltage drop is across the earth, not down the tower. 




> If its a paralleled circuit but i see it as a person grabbing onto a frame as the ground rod point its a new point of contact with its own voltage and current we all dont get shocked in a perfect location as MH shows .


The grounding electrode does not remove the voltage from the tower (or pole in the MH slide). The voltage remains on the tower until the fault is cleared. The grounding electrode only raises the voltage of the earth for a very small area around the electrode. As you get away from the electrode the voltage of the earth drops and a person standing on the earth and touching the tower is subjected to a higher voltage.


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## don_resqcapt19 (Jul 18, 2010)

Zog said:


> Exactly my point, I suspect the test is being done incorrectly, no way you get .08 ohms no matter what your soil conditions are. Piperunner, show me one FOP graph with a plateau at .08 ohms. Expain how you are conducting this test.


I suspect that the ground resistance tester being used is a clamp on type of tester and most of those do not work when being used with a large grounding grid or system. 
The following is from the instructions of one such meter.


> Measurements below 0.1Ω typically (or even 1Ω) indicate the ground tester is clamped onto a closed loop and that the signal is not flowing through the ground under test. ...
> Q. Can the clamp-on method be used for substation grid resistance testing?
> A. It depends. It can be used as long as the instrument can be clamped onto a point on the grounding system at a common point where it ties to the system neutral. Testing a grid must be treated as if it were a single electrode. Often, clamping on to points within the grid system will yield a closed loop reading.


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## Roger (Jul 7, 2007)

don_resqcapt19 said:


> I suspect that the ground resistance tester being used is a clamp on type of tester and most of those do not work when being used with a large grounding grid or system.


You are probably correct Don, it could also be that if it is a three point FOP test set it is not being used correctly.

Roger


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## user4818 (Jan 15, 2009)

piperunner said:


> Well dont go away yet Brian ,BBQ Roger, Jhall look at photo see the man next to the tower .
> 
> 
> 
> ...


I'm no engineer, but here's a common sense question for simpletons like myself. 

Somehow this poorly grounded tower is losing 4000 volts across it due to voltage drop before it reaches the bottom of the tower where the touch potential is show to be 1000 volts. Do you really believe that is possible? The entire tower is made of metal and is extremely low impedance relative to the ground. The tower is now part of the conductive path. Why would the touch potential only be 1000 volts if it's effectively become part of the circuit?


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## piperunner (Aug 22, 2009)

Peter D said:


> I'm no engineer, but here's a common sense question for simpletons like myself.
> 
> Somehow this poorly grounded tower is losing 4000 volts across it due to voltage drop before it reaches the bottom of the tower where the touch potential is show to be 1000 volts. Do you really believe that is possible? The entire tower is made of metal and is extremely low impedance relative to the ground. The tower is now part of the conductive path. Why would the touch potential only be 1000 volts if it's effectively become part of the circuit?



Well peter look at the text from florida power i wont say anything but its there book and read it for yourself .










I must say i think Florida power is correct on this but some say iam wrong and florida power is wrong .

Its hard for me to understand how florida power would teach this the wrong way .


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## piperunner (Aug 22, 2009)

don_resqcapt19 said:


> Exactly what ground resistance tester were you using and exactly what were you testing?


Well Don were using a Biddle megger DET4TC nothing special its a nice little tester and its easy to use it can do a four point test or a 3 point it can also test one rod . We run the test leads out and push button some we test but lately its done by a testing company .

The lowest reading you can get with this meter is 0.01 so thats fairly low in my book.

We test 3 days after a rain we test one rod at a time it well change ohm readings from high 14 ohms down to 6 ohms on one rod .

30 foot deep 5/8 copper/cad on the rods its in our specs on the job we dont do this for fun.

Next after that single test we run 4/0 cooper and cadweld them two rods which are 30 feet apart . 

We test these two to see what we have now we might be around 3 or less ohms next we cadweld all rods of three if it gos down less then one ohm we stop .

If it doesnt we add rods our rods are cadwelded together and that means not the wire but we cadweld the rods to the rods no screw couplings are used .

This is a typical install on most of our projects but the engineer calls out less than 5 ohms on every job since ive been in this trade . Monday ill post our spec s on grounding so you can see what is writing .


.


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> ...
> 
> 
> 
> ...


The issue is the statement that says, "A person touching the tower would be subjected to the voltage developed across the ground resistance". This statement is totally wrong. The voltage would be what ever voltage is between the tower and the point on the earth that the person is standing on. If there is a ground grid around the tower or if he is standing on the grounding electrode, there will be very little voltage. How ever if he is more than a few feet from the grounding grid or the electrode, he will receive 85% or more of the tower voltage as measured to "remote earth". "Remote earth" is defined as earth 50' or more away from any ground grid or grounding electrode. 

As far as teaching things wrong, there is a lot of wrong information out there about grounding and bonding. One of the biggest issues, is the fact that the NEC uses the term "equipment grounding, when they really mean "equipment bonding". The connection to earth does not make our system safe. It is the "bonding" bonding connection back to the power source that keeps our systems safer. Even with a solid bonding connection back to the power source, it is very possible to have fatal voltages on the bonded parts of the electrical system, as measured to earth, for the duration of the fault. The intent of the bonding system is to make sure that enough current flows to cause the OCPD to open in its instantaneous trip range.


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> ...
> This is a typical install on most of our projects but the engineer calls out less than 5 ohms on every job since ive been in this trade . Monday ill post our spec s on grounding so you can see what is writing .


I am not doubting that you have specs calling for this type of installation. I am only saying that the grounding electrode system won't do what FPL says it will in their text.


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## piperunner (Aug 22, 2009)

don_resqcapt19 said:


> I am not doubting that you have specs calling for this type of installation. I am only saying that the grounding electrode system won't do what FPL says it will in their text.



Well don read this its the same calculations with different numbers but i think florida power may be correct in there school book check this out .












Its the same as the power companys book just other voltages i see if you reduce the ground rod ohms you reduce touch potential near the rod close to it .

And from what i read doing the math the power company book is correct because this is the same way this new page has it .

Agree now Don lets look at this i have another engineering page which shows the same format just like these so i must say they all agree with a reduction in ohms to correct or make less the touch voltage not a elimination but a very good reduction .


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> Well don read this its the same calculations with different numbers but i think florida power may be correct in there school book check this out .
> 
> 
> 
> ...


So you are telling me it is safe if you reduce the ground potential rise from 50,000 volts to 35,000 volts??? 

Even so that is still the rise of the voltage of the grounding grid as compared to "remote earth". It provides no protection unless you are standing on the grounding grid itself. If you are on the earth even a few feet from the grounding grid you will receive a fatal shock. Large substation grounding grids are intended to make you like the bird on the wire....everything that is within reach or step is at the same voltage, and that works great as long as you are standing on the grid. It works by actually raising the voltage of the grid under the substation to that of the faulted equipment.
That would almost never be the case with your tower example. Even with the grounding grid, there will be a fatal step potential at the outside edges of the grid under fault conditions.


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## piperunner (Aug 22, 2009)

don_resqcapt19 said:


> So you are telling me it is safe if you reduce the ground potential rise from 50,000 volts to 35,000 volts???
> 
> Even so that is still the rise of the voltage of the grounding grid as compared to "remote earth". It provides no protection unless you are standing on the grounding grid itself. If you are on the earth even a few feet from the grounding grid you will receive a fatal shock. Large substation grounding grids are intended to make you like the bird on the wire....everything that is within reach or step is at the same voltage, and that works great as long as you are standing on the grid. It works by actually raising the voltage of the grid under the substation to that of the faulted equipment.
> That would almost never be the case with your tower example. Even with the grounding grid, there will be a fatal step potential at the outside edges of the grid under fault conditions.



No iam not saying its totally eliminated and safe now and no shock from a fault iam saying what i originally said that you can reduce the touch voltage by lowering the ground resistance which BBQ and Roger said was a waste of time .


But its not full voltage until your out past the grid yes past the grid or further from the rod .

I look at from 55,000 volts to 35,000 volts its a major factor when your working around the yard .

I agree with standing on that grid and thats why they install a grid in a yard we understand that .

I also agree with the distance further away off the grid your toast good ground doesnt make a hill that surface current will come to you .


But at 120 volts higher current will flow in the rod if you lower the rod R it might trip that breaker in a house not bad if you ask me .

And Don you said it was incorrect that the power company was wrong i see it as there correct in there calculations as shown .

But they did not show enough in there text or photo of what happens from a distance and left out the step voltage part but i think there intent and math was clear to me .

By the way that book is about 40 years old .

Do you agree that touch voltage can be less if you have a good ground like less than one ohms and florida power was showing that ?

I guess i should say Progress Energy now .

I was trying to say on all my posts but was hit by its only good for one thing lightning protection and thats not true its a important part of the system if and when needed .

I just dont like the 25 ohms !

Theres other grounding systems in our trade besides two rods but i guess most here just do residential work and see a mind set of put them two rods in and walk .

We were hoping to open up a window to show its really needed .

So i disagreed with them and now were here discussing how we can make a ground better .

But one thing and this is for Roger and BBQ if you can lower the rod resistance and increase the current flow at 120 volts that might just trip the breaker at 120 amps dont ya think and it may save a person from a shock .

As were all not standing at the ground rod when things happen we just might be in the kitchen eating dinner lights go out due to a fault and by the time you get up the breaker has tripped hummm .

We dont have faults every week but ill stick with a good ground rod system over a high resistance one any day .

At one ohm you would have lots of amps on that rod more so then at 25 ohms which to me is a lot better then staying on all week long at 15 amps BBQ .

It doesnt eliminate the issue but its better then the code states .





.


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> No iam not saying its totally eliminated and safe now and no shock from a fault iam saying what i originally said that you can reduce the touch voltage by lowering the ground resistance which BBQ and Roger said was a waste of time .
> 
> 
> But its not full voltage until your out past the grid yes past the grid or further from the rod .
> ...


So you have no problem walking up and touching something with a touch potential of 35,000 volts?



> I agree with standing on that grid and thats why they install a grid in a yard we understand that .


Yes and that is not even close to the condition with the tower and a ground rod. Unless you are on top of the grid or rod, there is very very little reduction in the shock potential. That is a rare case, almost always reserved to with-in a substation yard. 



> I also agree with the distance further away off the grid your toast good ground doesnt make a hill that surface current will come to you .
> But at 120 volts higher current will flow in the rod if you lower the rod R it might trip that breaker in a house not bad if you ask me .


There should never be a reason for fault current in a building system to have to flow through the grounding electrode. The fault path should always be via the EGC and the main bonding jumper. Yes the grounding electrode will be a parallel path and of course there will be some current on it, but the path via the EGC and main bonding jumper will have an impedance 100s if not 1000s of times less.



> And Don you said it was incorrect that the power company was wrong i see it as there correct in there calculations as shown .
> But they did not show enough in there text or photo of what happens from a distance and left out the step voltage part but i think there intent and math was clear to me .
> 
> By the way that book is about 40 years old .
> ...


No I don't agree that the grounding electrode system can reduce the voltage on an energized a metal part as measured to remote earth.



> I was trying to say on all my posts but was hit by its only good for one thing lightning protection and thats not true its a important part of the system if and when needed .


In fact, with a grounding electrode system installed for a building, its main two purposes are lighting protection and protection for when the utility has a primary to secondary fault of some type. 



> I just dont like the 25 ohms !


The code for the most part applies to building wiring system and they say 25 ohms because they know that the grounding electrode system does not really do much to improve the safety of the system.



> Theres other grounding systems in our trade besides two rods but i guess most here just do residential work and see a mind set of put them two rods in and walk .


Not sure about that, but again with building wiring systems a better grounding electrode does not change the safety of the system.



> But one thing and this is for Roger and BBQ if you can lower the rod resistance and increase the current flow at 120 volts that might just trip the breaker at 120 amps dont ya think and it may save a person from a shock .


Only if the system is not properly installed. There will never be a grounding electrode that would have a lower impedance than the EGC and the main bonding jumper.


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## piperunner (Aug 22, 2009)

Well Don very good points made you have made it clear and answer all my questions and thanks for the lesson your answers were good i understand better what a ground rod is for .





And were not touching 35kv .

Take care Don


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## RIVETER (Sep 26, 2009)

Zog said:


> Oh really?  You think I should BE taking notes on YOUR posts?:laughing:


Hey, Zog. Just for clarification, when we use the term, "Fall of potential", Are we meaning that as we get farther from the first rod, are we seeing less of a potential difference?


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## piperunner (Aug 22, 2009)

Well from what i just went though your getting more voltage away from the rod and thats not called fall of potential thats called step voltage .

Closer to the rod is less further away from rod or grid is more step off matt or grid and its full voltage .




Fall of potential is the type or name of the test made on the rod your testing which is the voltage measured during the testing of the rod voltage drop of the earths resistance to your rod tested.

Are you really asking this seems like you do alot of plant work .


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## bobelectric (Feb 24, 2007)

piperunner said:


> Well dont go away yet Brian ,BBQ Roger, Jhall look at photo see the man next to the tower .
> 
> 
> 
> ...


I would have to say the footers are 20' or more,with anchor bolts, giiving a good Ufer ground.


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## piperunner (Aug 22, 2009)

bobelectric said:


> I would have to say the footers are 20' or more,with anchor bolts, giiving a good Ufer ground.


I pretty much gave up when they said Progress Energy was not correct in its example of step voltage .

Talked to my next door neighbor who has worked as a engineer for them for twenty eight plus years .

And he says what - blank- blank- blank - soooo basically PGE formulas are correct and shows what happens to voltage during ground to step voltage from a tower or any metal gear and says its the same with any ground rod .

So i asked him about the 25 ohms per NEC he say hes glad that they dont have to follow the Nec because most plant engineers would be dead.

The deeper you go or the more area you cover is best .


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## Roger (Jul 7, 2007)

piperunner said:


> I pretty much gave up when they said Progress Energy was not correct in its example of step voltage .
> 
> Talked to my next door neighbor who has worked as a engineer for them for twenty eight plus years .
> 
> ...


I don't know your neighbor but obviously he is drinking the same tainted water you are or vice versa. 

Roger


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## piperunner (Aug 22, 2009)

Roger said:


> I don't know your neighbor but obviously he is drinking the same tainted water you are or vice versa.
> 
> Roger



Well Roger maybe its the water table in Florida .

This is what he said 

The deeper you go effects the step voltage and the distance from metal parts to touch potential changes in voltage within that depth of soil space around the rod . 

That high voltage travels near surface not on surface but near upper layer also depends on soil types and the area .

Thats why a grid or matt is used on or in a yard.

That a lower voltage does not take that path and that current would be at its lowest if directed deeper into earths soil . 

Also the measured voltage to ground thats supplied at the source effects this touch potential .

And this will blow your mind do you think voltage to ground is effected by the location of not just depth or soil but were we are located on this earth of ours think about that .

Deeper ground rod area in the earths soil drops the step voltage down less ohms drops the step voltage its not going away but its better than 25 ohms .

And 25 ohms is not good . 

But less than 5 is better .

Less than one is great .

Why would anyone want just enough protection seems most engineers that we have on jobs prefer less then 5 ohms wonder why that is .


My question to my next electrical engineer on my next new project will be this question why and how and explain it in detail because iam getting many folks with different ground rod theory issues .

Maybe these engineers are out selling copper ground rods or wire humm .

I will get to the bottom of this ground rod issue no pun there and will dig deeper into this step voltage question . 

Ill keep you posted Roger i know you cant wait .


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## Roger (Jul 7, 2007)

piperunner said:


> Maybe these engineers are out selling copper ground rods or wire humm .


No, if it's a POCO engineer he is setting up his argument for when the neutral is lost to a customers home or building. A POCO engineer will almost always use the argument that if you had a good earthed (ground rod) system, even though their neutral came loose, your TV, Freezer, Stereo, Ceiling Fans, etc... would not have seen a surge so therefor it's your (the customers) fault and they bear no responsibility for their problem. They definitely have a reason besides theory to argue (although bogus) that a ground rod is people and property protection. 

Remember, you are talking to one engineer whereas the information from the IEEE Green Book is written from a group of his peers.



piperunner said:


> I will get to the bottom of this ground rod issue no pun there and will dig deeper into this step voltage question .
> 
> Ill keep you posted Roger i know you cant wait .


 Actually, I can. 

Roger


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## bobelectric (Feb 24, 2007)

I never worked on h.v towers, but I worked on smaller sub station installs where the grounding grid was formost # 1 of importance.


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## piperunner (Aug 22, 2009)

Roger said:


> No, if it's a POCO engineer he is setting up his argument for when the neutral is lost to a customers home or building. A POCO engineer will almost always use the argument that if you had a good earthed (ground rod) system, even though their neutral came loose, your TV, Freezer, Stereo, Ceiling Fans, etc... would not have seen a surge so therefor it's your (the customers) fault and they bear no responsibility for their problem. They definitely have a reason besides theory to argue (although bogus) that a ground rod is people and property protection.
> 
> Remember, you are talking to one engineer whereas the information from the IEEE Green Book is written from a group of his peers.
> 
> ...



Well ok read this its a study on ground rods which kinda says it all.

Were not talking fault or lightning protection only but what a ground rod is besides just a 25 ohm connection to earth and in two weeks its up to 100 ohms with cheap clamps and a galvanized rod waste of time . Were looking at the whole picture not just a house or mobile home .

http://www.cpccorp.com/deep.htm

But its not the only paper on this .


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## Roger (Jul 7, 2007)

piperunner said:


> Well ok read this its a study on ground rods which kinda says it all.
> 
> Were not talking fault or lightning protection only but what a ground rod is besides just a 25 ohm connection to earth and in two weeks its up to 100 ohms with cheap clamps and a galvanized rod waste of time . Were looking at the whole picture not just a house or mobile home .
> 
> ...


If we were worried about our computer getting shocked from a touch potential hazzard I guess the paper is ok  but, that is not the discussion at hand, sensitive electronic equipment and their power supplies using earth as part of their circuit is not the topic of this conversation. 


Roger


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## piperunner (Aug 22, 2009)

Well its all about ohms and ground rods thats the topic thats what ive been talking about a ground rod is and does have a purpose other than just install it and walk away .


I would think a data center might be interested a little maybe not a homeowner .

Maybe the Martin Lockheed plant might need a good ground .

Even NASA or that big Fairchild chip plant hummmm na just put in two rods were good to go .

Yes if you go by the code which to me is not worth installing a rod in the ground in the first place at 25 ohms as no one test them anyway so its alot higher maybe even 100 ohms with a cheap ground rod clamp thats good for a lightning hit this way it gos through the house instead .

But i was told you can not get 5 or less ohms which we do on every job right here in central Florida .

Next time i test iam making a video just for you guys .

I was told we cant get less than a ohm which the megger ground tester we use goes down to 0.01 ohms and its a three point or four point and it can check one rod if needed if you need me to prove that i will.

If you go deeper its just better but thats what iam pretty sure i was posting about .


The whole point of my post was that a ground rod is needed at a lower ohm reading for the general electrical trade not just whos online here or you or the NEC .


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## BBQ (Nov 16, 2010)

piperunner said:


> Well its all about ohms and ground rods thats the topic thats what ive been talking about a ground rod is and does have a purpose other than just install it and walk away .


Hold up there piper, here is where all this started.





piperunner said:


> Well if your grounding is not good well
> *Ouc Offers To Buy 2 Horses For Police*
> 
> *Money For The Steeds To Replace Two That Were Electrocuted Will Come From A Fee Paid By Hbo.*
> ...


I pointed out that a better grounding electrode would not have saved those horses and that is still a fact.


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## piperunner (Aug 22, 2009)

BBQ said:


> Hold up there piper, here is where all this started.
> 
> Thats piperunner mister !
> 
> ...



I think they were old anyways so we did the police dept a favor .

And dont you start again i can only have one debate at a time .


Were beating a dead horse i just had to add that .


25 ohms you will never change my mind .


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## BBQ (Nov 16, 2010)

piperunner said:


> 25 ohms you will never change my mind .



As I have already pointed out ......... you closed your mind to new ideas long ago so ........ that really sucks for you.


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## piperunner (Aug 22, 2009)

BBQ said:


> As I have already pointed out ......... you closed your mind to new ideas long ago so ........ that really sucks for you.



Well my mind is looking at what is old 25 ohms is old news.

The code book is old news.


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## BBQ (Nov 16, 2010)

piperunner said:


> Well my mind is looking at what is old 25 ohms is old news.
> 
> The code book is old news.


Are you drunk? :laughing:


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## user4818 (Jan 15, 2009)

BBQ said:


> As I have already pointed out ......... you closed your mind to new ideas long ago so ........ that really sucks for you.


To me, it's pretty simple. If Piperunner wants to believe that an ultra-low earth impedance via the grounding electrode system is somehow beneficial to the operation of a premises wiring system, let him believe that. 

As we know the from the NEC, if we install a 4000 amp service in the middle of the desert all by itself, all we have to do is drive 2 rods, attach a #6 and we are done. The NEC does not require these elaborate systems that these engineers do, so that tells me the engineers are being bought off by copper.org.


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## piperunner (Aug 22, 2009)

BBQ said:


> Are you drunk? :laughing:


Nop :laughing: 

Well to answer Peter D if it was a 4000 amp it would not be a no.6 per the NEC code more like a 2/0 or 3/0 

Per art 250.66 grounding electrode conductors .

Size of largest ungrounded parallel conductors .


We only get drunk during a hurricane and this one passed by us .

Question BBQ you say your company does large projects and what your telling me is you never have installed three rods deep 20 foot 30 foot say a least 20 foot apart with couplings in a delta and had to get less than 5 ohms is that what your stating . HUMMMM

That any project you have done you have install two rods and never tested them .

And you dont need a record of the test for the electrical engineer to see .


I know this is a standard 1600 in most specs on any commercial large project not just our work but any contractors work not just in florida today and in the past boiler plate or not its been around for many years in the standard specs on any job .

So in the past you told me your company did big jobs how big because any good size project will have this in there spec and on there drawns & plans & details .

Not just me its all over the USA if you do commercial work of any size .

READ THIS http://www.nemasurge.com/news/grounding.pdf


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## Jlarson (Jun 28, 2009)

God I thought this, lets can it an argument died a long time ago. 

Over grounding (going above NEC requirements) if you aren't doing surge protection (serious SP, not like one little resi panel protector) and LPS is a waste of money. 

I routinely recommend (to the client) that extra grounding specs be removed on projects lacking thoes two items because it is unnecessary. 



piperunner said:


> Well to answer Peter D if it was a 4000 amp it would not be a no.6 per the NEC code more like a 2/0 or 3/0


No, you are not required to run larger then 6 copper or 4 aluminum to a rod, or a plate, or pipe electrode for that matter. And the jumper to another of those electrodes (as a supplementary electrode) doens't need to be bigger then 6 or 4 either.


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## piperunner (Aug 22, 2009)

Jlarson said:


> God I thought this, lets can it an argument died a long time ago.
> 
> Over grounding (going above NEC requirements) if you aren't doing surge protection (serious SP, not like one little resi panel protector) and LPS is a waste of money.
> 
> ...



GEE its better to talk about a tool pouch you get more hits or maybe a battery drill .


Well lets read art 250.66 shall be given in table 250.66 shall not be less than except as permitted in which a 4000 amp service its not permitted due to the size of the service entrance conductors .


Which commonly is a group of paralleled conductors show me a 4000 amp service with a no 4 cu GEC to one rod .

What size its what ever the engineer picks when he designs his feeders coming into a service could be many different sizes.

So my next service ill put a no# 6 cu or a 4 Alu grounding electrode conductor on one rod at 25 ohms a 4000 amp service and tell them its what its says in the code and iam not using table 250.66 .

Iam using 250.66 A what do ya think will happen ?


A# Engineer will agree ? 


B# They will send me in for a check up ?


C # Send me in for counseling at the local substance abuse center ?


Size of largest conductor or equivalent area thats what i see per table .

and if not you can use A - B - C .

Not that you use it on any service you wish to you need to come on our project and talk with our owners a project engineer id really like to see that .

Never seen a 4000 amp service with out surge protection ever for that matter ive never done a service with just one service entrance we always have 4 service in coming to five coming in .


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## BBQ (Nov 16, 2010)

piperunner said:


> Well lets read art 250.66 shall be given in table 250.66 shall not be less than except as permitted in


Lets do that, lets us read 250.66



> *250.66 Size of Alternating-Current Grounding Electrode
> Conductor.* The size of the grounding electrode conductor
> at the service, at each building or structure where
> supplied by a feeder(s) or branch circuit(s), or at a separately
> ...


4000 amp service could be code compliantly installed with only a 6 AWG copper to rod(s).


:thumbup:


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## piperunner (Aug 22, 2009)

BBQ said:


> Lets do that, lets us read 250.66
> 
> 
> 
> ...



I dont see it that way i see using the table whats the table for if you only need a no 6 awg and two rods ?



Heres a typical grounding one line we see on most projects










So ill just install or submit a request to change my 4/0 cu to a no 6 cu and thats the NEC code just tell them table 250.66 is not any good we dont need that 4/0 .


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## BBQ (Nov 16, 2010)

piperunner said:


> I dont see it that way i see using the table whats the table for if you only need a no 6 awg?


For the things 250.66(A), (B) or (C) do not cover.





> Heres a typical grounding one line we see on most projects


Here is a typical picture from my vacation.











Both are nice but entirely irrelevant to the NEC requirements.:thumbsup:


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## piperunner (Aug 22, 2009)

BBQ said:


> For the things 250.66(A), (B) or (C) do not cover.
> 
> 
> 
> ...


Dosent cover what ?


Were is that at so i dont go there ever !!! just kidding BBQ :laughing:

Great shot must be nice !


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## Jlarson (Jun 28, 2009)

I'm glad I have all the engineers I work with trained not to waste money. Having direct input in the design and value engineering of projects has perks.


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## BBQ (Nov 16, 2010)

piperunner said:


> Were is that at so i dont go there ever !!! just kidding BBQ :laughing:
> 
> Great shot must be nice !


Thanks, it is the White Mountain National Forest area in New Hampshire.

I am going back up Thursday, I love it up there.


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## user4818 (Jan 15, 2009)

piperunner said:


> Nop :laughing:
> 
> Well to answer Peter D if it was a 4000 amp it would not be a no.6 per the NEC code more like a 2/0 or 3/0


Sure, it might be. But my example was a service in the middle of the desert with only a few ground rods. 

Answer me these simple questions. What practical benefit does having an ultra low ground impedance have in a premises wiring system? What purpose do you think it serves?


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## BBQ (Nov 16, 2010)

Peter D said:


> What practical benefit does having an ultra low ground impedance have in a premises wiring system? What purpose do you think it serves?



To add to that..

How well do you think a rod 'connects' to the earth?


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## piperunner (Aug 22, 2009)

BBQ said:


> Thanks, it is the White Mountain National Forest area in New Hampshire.
> 
> I am going back up Thursday, I love it up there.


Looks like your having a good time and your family ill be nice when your on vacation take care BBQ .:thumbsup:


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## piperunner (Aug 22, 2009)

Jlarson said:


> I'm glad I have all the engineers I work with trained not to waste money. Having direct input in the design and value engineering of projects has perks.


Well i dont work with a Electrical Engineer we work and install what they design and ive never seen a no.6 cu on any job installed since ive been in the trade it just is not done ever but we do not due anything less than a 4000 amp service ever .

So do we our company does the same we help with the design but your not going to change the grounding system on the stuff we do and i would not ask it of them .

I think your full of it myself you would have to think iam a idiot to think your getting a EE to approve a number 6# or number 4# on any 4000 amp main not in this life time .


You show me how you train a EE on a 20 to 40 million dollar project theres about 25 electrical engineers on one project for just the electrical systems .


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## piperunner (Aug 22, 2009)

Peter D said:


> Sure, it might be. But my example was a service in the middle of the desert with only a few ground rods.
> 
> Answer me these simple questions. What practical benefit does having an ultra low ground impedance have in a premises wiring system? What purpose do you think it serves?



Well out in the desert thats mr uffer that works alot better than a ground rod just a wire layed under your footer .

Ground rod is useless in sand .

A uffer is better


Low impedance well just read what the experts say in the other post i gave you the site


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## piperunner (Aug 22, 2009)

PETER D 


Low impedance well just read what the experts say in the other post i gave you the site[/quote]

Ask a sound tech at Disney or Universal studios whats the best ground they will disconnect the branch grounding conductor and i mean cut it off on some of there high tech equipment .

They say they need a earth point humm ask them why they need a isolated point but no connection to other electrical systems so they use the earth . mostly on audio equipment and sound .They even want rigid conduit on this no pvc no emt . But they want the lowest ohms they can get from that point


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## user4818 (Jan 15, 2009)

piperunner said:


> PETER D
> 
> 
> Ask a sound tech at Disney or Universal studios whats the best ground they will disconnect the branch grounding conductor and i mean cut it off on some of there high tech equipment .
> ...


Everything you just described is extremely hazardous and an NEC violation.

But again, we still haven't gotten to the heart of the matter, which is why we need such low ground impedance for a typical premises wiring system. What is the net benefit for the $100's of thousands spent on copper, hardware and installation cost? Electrons don't behave any differently in a house, or a retail store, or a high rise building.


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## Roger (Jul 7, 2007)

piperunner said:


> Ask a sound tech at Disney or Universal studios whats the best ground they will disconnect the branch grounding conductor and i mean cut it off on some of there high tech equipment .


That's because they have no clue as to how the circuit to their equipment works. Just because they have the word Technician attached to their job description doesn't mean they're not idiots (they are) and they certainly are not gods. 


You will be much better informed listening to the people in this thread

Roger


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## Big John (May 23, 2010)

I'm starting to think _Soars Book on Grounding_ should be required reading to get continuing education credits.

-John


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## piperunner (Aug 22, 2009)

Roger said:


> That's because they have no clue as to how the circuit to their equipment works. Just because they have the word Technician attached to their job description doesn't mean they're not idiots (they are) and they certainly are not gods.
> 
> 
> You will be much better informed listening to the people in this thread
> ...


Well Roger what size grounding electrode conductor for a 4000 amp service to a ground rod . per code if you agree with these folks on the forum they say a no. 6 and one rod or two if you dont get 25 ohms .

Which i dont agree with i use the table .

Now why do they have a table 250.66 thats in the code book if all you need is a no 6 for any service .

Peter d dont do resisdential work and i dont care what you use for a home iam talking about commercial work only .


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## user4818 (Jan 15, 2009)

piperunner said:


> Well Roger what size grounding electrode conductor for a 4000 amp service to a ground rod . per code if you agree with these folks on the forum they say a no. 6 and one rod or two if you dont get 25 ohms .
> 
> Which i dont agree with i use the table .
> 
> ...


Throughout this thread I have given you the benefit of the doubt, but I agree with BBQ and Roger now, your mind is closed and you simply aren't open to changing your mind about this. 

I'm fully aware that commercial and industrial specs often greatly exceed NEC requirements. But that's not what we are talking about here. We are talking about what will work, electrically speaking. My contention is that a premises wiring system will function and perform adequately with a code minimum grounding electrode system. You can attach a 750 to a ground rod or series of ground rods and it's not going to perform any better than a #6. If you can't wrap your mind around this concept, I'm not sure what else I can use as an example to change your mind.


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## Roger (Jul 7, 2007)

piperunner said:


> Well Roger what size grounding electrode conductor for a 4000 amp service to a ground rod .


 A #6 and that would be applicable for as many rods as you wanted to drive.

BTW, the answer would be the same for what ever size service you want to use for the example be it residential, commercial, or industrial.


Roger


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## BBQ (Nov 16, 2010)

piperunner said:


> what size grounding electrode conductor for a 4000 amp service to a ground rod . per code if you agree with these folks on the forum they say a no. 6 and one rod or two if you dont get 25 ohms .
> 
> Which i dont agree with i use the table .
> 
> Now why do they have a table 250.66 thats in the code book if all you need is a no 6 for any service .


Pipesmoker, I posted the code sections, they are very clear, the fact that you cannot see that tells me you are either a troll or really boneheaded. :laughing:


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## piperunner (Aug 22, 2009)

Peter D said:


> Throughout this thread I have given you the benefit of the doubt, but I agree with BBQ and Roger now, your mind is closed and you simply aren't open to changing your mind about this.
> 
> I'm fully aware that commercial and industrial specs often greatly exceed NEC requirements. But that's not what we are talking about here. We are talking about what will work, electrically speaking. My contention is that a premises wiring system will function and perform adequately with a code minimum grounding electrode system. You can attach a 750 to a ground rod or series of ground rods and it's not going to perform any better than a #6. If you can't wrap your mind around this concept, I'm not sure what else I can use as an example to change your mind.


You will never change my mind Peter on a low ohm grounding system .

But its good to hear everyones reason why iam wrong 25 ohms because the code says it ok .

Its my thought that the code is wrong but yes if thats what they think is the minimum resistance for folks in there homes then fine .


Well lets look at the table what is it for in art 250 .66 someone made the statement that all you need is a no.6 and thats just not true .

The larger the service and the service feeders coming in you can not just use a no 6 wire on a 4000 amp service .

I can see in a home i would say its minimum protection with a number 6 wire but i dont see that in commercial .

If i had a choice to install a no.6 at my home service i would not i would go larger like a 3/0 just for me because i dont like minimum .

Because i think the low ohm is a better connection to ground earth .

Roger and peter grounding removed by techs was a example of what people do we dont do it they do it which is there business so yes we agree with thats a code issue they have there reasons . 
Once were done its there building they say they get loop currents tiny microvolts in the grounding system which effects sound & audio microphones and things like that .

Interference with you standard ground branch circuit so they cut it off not my problem i dont care it was just a point .

Point was why they did it .

But they need that earth ground for audio to work .

Why do we put in a more than one rod to get less ohms .



But if a no 6 is used on all services why do we have a table with a larger size grounding electrode conductor .


What is that table for it should be taken out of the code book if noone uses it .

Peter the reason is a better connection to ground earth soil .

So if you need it some day its a good earth connection .


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## Roger (Jul 7, 2007)

piperunner said:


> But if a no 6 is used on all services why do we have a table with a larger size grounding electrode conductor .


I think I finally see the problem, you don't understand the difference in the elctrodes covered under the Table verses a rod. As BBQ has pointed out, there is more to article 250.66 than just the table and until you can comprehend the whole article you will not be able to grasp what is being told to you.

BTW, there are services in the Artic and Anartic circles with sensitive electronic equipment operating off of them and there is no earthed electode. With that being the case, if a low resistance to earth is paramount to these items operating, how do you explain these pieces of equipment working without a low resistance connection to earth?

Roger


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## Jlarson (Jun 28, 2009)

piperunner said:


> You show me how you train a EE on a 20 to 40 million dollar project theres about 25 electrical engineers on one project for just the electrical systems .


When they do a good job you give them a treat like a free lunch when they waste money no treat. It's like dog training. :jester:

In reality I only work with engineers that actually understand the NEC. They're out there you just have to find them.


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## piperunner (Aug 22, 2009)

Roger said:


> I think I finally see the problem, you don't understand the difference in the elctrodes covered under the Table verses a rod. As BBQ has pointed out, there is more to article 250.66 than just the table and until you can comprehend the whole article you will not be able to grasp what is being told to you.
> 
> BTW, there are services in the Artic and Anartic circles with sensitive electronic equipment operating off of them and there is no earthed electode. With that being the case, if a low resistance to earth is paramount to these items operating, how do you explain these pieces of equipment working without a low resistance connection to earth?
> 
> Roger


Explain what the table is for Roger why is it there ?

What size grounding electrode conductor on a 4000 amp main service or a 5000 amp main ?

For what grounding electrode conductor attached to what a rod or plate is there another attached device i missed ?

The artic is ground its all ice ground is earth soil as water or ice common like the earth itself get real a ship uses it steel structure thats grounded common to the ship water around it electrical all points made of a area or mass .


Gee i better tell the space center that testing and installing low ohms is a waste .

Kennedy space center low ohms per spec on there work service ground rods . plus other additional grounding systems in use .

The old Martin plant orlando when they had a defense plant major low ohms with service ground rods . Meaning munitions plant!

fairchild chip plant low ohms on there service rods .

Semiconductor plants we have a few here in florida antistatic grounding out of this world and service low ohms . Need a list of the ones our company has done only three in florida .

Most fuel storage & gas storage low ohms on system with posistive ground recognition units which means if you dont have less than 10 ohms the fuel dont pump it dont work .

Wonder why ?

Roger weve been around a few years and were not going to listen to your code book minimum regulations as far as your engineers go i think you need to look at the whole scope of work folks due theres kinda other areas beside what the forum sees .

The code is just a rule not a engineering rule to use and there wrong .


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## user4818 (Jan 15, 2009)

piperunner said:


> Roger weve been around a few years and were not going to listen to your code book minimum regulations as far as your engineers go i think you need to look at the whole scope of work folks due theres kinda other areas beside what the forum sees .
> 
> The code is just a rule not a engineering rule to use and there wrong .


:laughing::laughing:


I'm pretty sure Roger has been around a few years too and does the same kind of jobs you do. You'd be wise to listen to him. :yes:


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## Big John (May 23, 2010)

piperunner said:


> ...I think you need to look at the whole scope of work folks due theres kinda other areas beside what the forum sees....


 I think you're getting a full of yourself, man.

You may have done a lot of big projects, but I guarantee you there are a lot of folks on here who can match you job-for-job and then some. 

When there is this much accumulated knowledge and wisdom on one forum it's ridiculous to assume that everyone who thinks differently than you must be wrong.

-John


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## BBQ (Nov 16, 2010)

Peter D said:


> I'm pretty sure Roger has been around a few years too and does the same kind of jobs you do. You'd be wise to listen to him. :yes:


:thumbsup: Without a doubt.


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## BBQ (Nov 16, 2010)

Roger said:


> BTW, there are services in the Artic and Anartic circles with sensitive electronic equipment operating off of them and there is no earthed electode. With that being the case, if a low resistance to earth is paramount to these items operating, how do you explain these pieces of equipment working without a low resistance connection to earth?


:thumbsup:

It dawned on me the other day this thread really needs Benny Palmer.


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## piperunner (Aug 22, 2009)

Big John said:


> I think you're getting a full of yourself, man.
> 
> You may have done a lot of big projects, but I guarantee you there are a lot of folks on here who can match you job-for-job and then some.
> 
> ...


Never said there was not but lets talk dont shut me down iam still here just have a different view on electrical and how its done .

Well get over what because i think that a low ohm connection is better and have seen it on every job that we have ever done .

Were making a point of what we have seen . 

Come on were just pointing out whats wrong with 25 ohms .

Tell me why iam wrong .

No one can explain why the table is not used we use it on all projects .

You think that were trying to prove were better then you thats not what were hear for were here to say we dont agree with the code . And no one will answer my question on a 4000 amp service what size grounding electrode conductor is used a no# 6 or the table ?

If we install it at 25 ohms next week its higher if we wait long enough its not worth installing in the first place .

Thats my point and i dont agree with the NEC .


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## Roger (Jul 7, 2007)

BBQ said:


> :thumbsup:
> 
> It dawned on me the other day this thread really needs Benny Palmer.


Yes it does. 

BTW, thanks for the support BBQ, Peter, Big John, and JLarson.

Roger


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> Well Roger what size grounding electrode conductor for a 4000 amp service to a ground rod . per code if you agree with these folks on the forum they say a no. 6 and one rod or two if you dont get 25 ohms .
> 
> Which i dont agree with i use the table .
> 
> ...


If all you have as a grounding electrode is a rod or two, why would you run a GEC larger than #6? What would it do? A #6 can carry more current than a rod of two can conduct to the earth.


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## don_resqcapt19 (Jul 18, 2010)

piperunner said:


> ...
> Well get over what because i think that a low ohm connection is better and have seen it on every job that we have ever done .
> 
> ...


What exactly does having a grounding electrode system with a very low impedance do for an electrical system. The only function of a grounding electrode in a correctly designed and installed electrical system is protection from lightning and protection for the system if a higher voltage system comes into contact with it. It does almost nothing for the safety of the system.


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## user4818 (Jan 15, 2009)

piperunner said:


> Low impedance well just read what the experts say in the other post i gave you the site


I read the link. Now explain something to me. How do sensitive electronics function perfectly well in cars, airplanes, trains, and other vehicles with no connection to earth? Since Bennie Palmer's name was mentioned in this thread, it was he who joked about the bucket of dirt for a good ground connection.


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## piperunner (Aug 22, 2009)

Peter D said:


> I read the link. Now explain something to me. How do sensitive electronics function perfectly well in cars, airplanes, trains, and other vehicles with no connection to earth? Since Bennie Palmer's name was mentioned in this thread, it was he who joked about the bucket of dirt for a good ground connection.



Well were not in a car or a airplane lets say were in a plant that makes chips
or maybe a fuel area like rocket fuel not just any ground will due that said look at these specs typically read as follows .

Now what do i do tell the engineer hes not doing this the way the NEC says we only need a no.6 and one ground rod .

No i do it because you need a common earth ground inside some projects its not just lightning .

Its earthing all parts its giving a ground not attached to your branch equipment ground a point to attach too. for static discharging or bonding to keep a low potential from becoming a flash . additional point back too and isolated to main ground point.










This is one of the worst job specs we have ever seen normally its 5 ohms or less . 

Pete were not given you a hard time but understand we dont make the rules we go by them . 

We can not change any grounds theres always a reason and its not in the code book .


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## user4818 (Jan 15, 2009)

piperunner said:


> Pete were not given you a hard time but understand we dont make the rules we go by them .
> 
> We can not change any grounds theres always a reason and its not in the code book .


I fully understand you build your jobs to the specs you're given. Nobody here, myself included, has said not to do that. I also understand that your jobs greatly exceed the NEC requirements. 

All we are saying is that a low impedance grounding system does not offer any benefits to a premises wiring system other than lightning protection and incidental contact. It's really that simple.


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## piperunner (Aug 22, 2009)

don_resqcapt19 said:


> What exactly does having a grounding electrode system with a very low impedance do for an electrical system. The only function of a grounding electrode in a correctly designed and installed electrical system is protection from lightning and protection for the system if a higher voltage system comes into contact with it. It does almost nothing for the safety of the system.


Well Don we must disagree there are projects which call out for a low ohm system installed for special connections to all parts of the project .

Yes i understand that 25 ohm per Nec is good for a home or a small commercial install but we have never been there i dont know what that is. .

Every job we do is less than 5 ohms per specs .

Chip plant Litton Laser had static discharge units used the GEC for attachment .

Martin plant used it also for ground they needed a separate system to attach to for there use this was when they made the walleye rocket and had a tank plant which we did back then in Orlando .

There use was just a point to attach but it was a low ohm rule and it had a purpose .

We have ground bars by the hundreds when we connect to the whole system its less ohms than the equipment ground running back with the branch circuits or feeders from a switchboard or panel .

I really think if we had a fault it would follow the grounding electrode conductor system back to the service before the equipment ground by the nature of that low ohms plus all the connections to it . Its a lower ohm path back the resistance of the equipment branch is at a higher ohm than the grounding electrode conductor system installed . 

Meaning not earth totally but as its a common system of copper everywhere that fault would travel back to the source neutral if needed by its low ohm connection .

Its just not a normal grounding system every part is bonded we also run a ground wire with each feeder and branch we do not use the conduit as ground ever .

Each panel encloser is attached to the ground bars in that room which go back to the main rods at the service . We even cad weld to the floor matt steel on each level its over kill but what can i say .

That said i feel its safer than a 25 install any day .


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## piperunner (Aug 22, 2009)

Peter D said:


> I fully understand you build your jobs to the specs you're given. Nobody here, myself included, has said not to do that. I also understand that your jobs greatly exceed the NEC requirements.
> 
> All we are saying is that a low impedance grounding system does not offer any benefits to a premises wiring system other than lightning protection and incidental contact. It's really that simple.


We agree with that peter yes .

When we see a post we never think about anything but what we have been working on its hard to see another system many years and you get that mind set .

Doing the same stuff over and over if i did a house it would be a expense project and the owner would flip out .

Hey were we gona put these 18 ground rods in the flower bed :laughing: 

Sorry man i get going sometimes and its one way blinders but if you guys didnt have me here you wouldt have anyone to mess with look at it that way .


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## bobelectric (Feb 24, 2007)

Piperunner,

Submit your code changes to the code making panel.


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## RIVETER (Sep 26, 2009)

Peter D said:


> I fully understand you build your jobs to the specs you're given. Nobody here, myself included, has said not to do that. I also understand that your jobs greatly exceed the NEC requirements.
> 
> All we are saying is that a low impedance grounding system does not offer any benefits to a premises wiring system other than lightning protection and incidental contact. It's really that simple.


I have heard of a hi-impedance grounding system and its benefits. One of which is that it is not a 24/7 I2R loss. Another advantage, or so I am told, is that it is easier to find and unintentional ground in the system with certain equipment. However, I am talking about a system comparison between a hi- resistance grounded system and a hi- impedance one when attempting to get some of the advantages of an un-grounded system.


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## BBQ (Nov 16, 2010)

piperunner said:


> Well Don we must disagree there are projects which call out for a low ohm system installed for special connections to all parts of the project .


There are many jobs that require many things.

These 'low ohm' systems are not for the protection of people from groundfaults. 



> Yes i understand that 25 ohm per Nec is good for a home or a small commercial install but we have never been there i dont know what that is. .


Well you are a God so we know you never wired a house. 



> Every job we do is less than 5 ohms per specs .


Great! 



> Chip plant Litton Laser had static discharge units used the GEC for attachment .
> 
> Martin plant used it also for ground they needed a separate system to attach to for there use this was when they made the walleye rocket and had a tank plant which we did back then in Orlando


Now what do any of those things have to do with the original issue? The horses electrocuted by a light pole.




> We have ground bars by the hundreds when we connect to the whole system its less ohms than the equipment ground running back with the branch circuits or feeders from a switchboard or panel .


You seem to think none of us have had to install all that ourselves or even seen it.

I have done over the op ridiculous grounding requirement jobs, I know Roger has and I bet Don has along with many more of us. You are not telling us some sort of secret that only you know about. :laughing::laughing:




> I really think if we had a fault it would follow the grounding electrode conductor system back to the service before the equipment ground by the nature of that low ohms plus all the connections to it . Its a lower ohm path back the resistance of the equipment branch is at a higher ohm than the grounding electrode conductor system installed .


I beg you, by the Soares book on Grounding. http://www.amazon.com/Soares-Book-Grounding-SOARES/dp/1890659274 You really are missing the boat here.

The grounding electrode systems is not intended to, is not designed to nor is it allowed to have any part in fault clearing at the voltage levels we are talking about. 



> Meaning not earth totally but as its a common system of copper everywhere that fault would travel back to the source neutral if needed by its low ohm connection .


The best path, the path with the lowest impedance will always be a properly installed EGC and bonding jumper.



> Its just not a normal grounding system every part is bonded we also run a ground wire with each feeder and branch we do not use the conduit as ground ever .


Again, nothing new here.



> Each panel encloser is attached to the ground bars in that room which go back to the main rods at the service . We even cad weld to the floor matt steel on each level its over kill but what can i say .


Yes, common but it still has noting to do with what we were talking about. 



> That said i feel its safer than a 25 install any day .


None of that bonding has anything to do with the connection to earth.

The connection to earth was what we were talking about and that is at the electrodes and has nothing to do with a bonding jumper from a panel to building steel.


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## RIVETER (Sep 26, 2009)

Peter D said:


> I read the link. Now explain something to me. How do sensitive electronics function perfectly well in cars, airplanes, trains, and other vehicles with no connection to earth? Since Bennie Palmer's name was mentioned in this thread, it was he who joked about the bucket of dirt for a good ground connection.


In every vehicle, US or foreign, in the left side of the trunk under a panel covered by carpet there is a bucket of dirt. It works well.


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## piperunner (Aug 22, 2009)

Well impressed with you essay could not find any words misspelled good punctuation and i could follow each sentence . 

Iam glad your helping me with this grounding issue i see the light now its getting brighter .

Just hand full of dirt is a good ground in a pot .


Iam learning so much from your posts i just cant wait for the next issue so i can learn more about how things work electrically . 


I just wish they had a Electricians forum 40 years ago gee what I have missed out on and other fellow forum members .

Just think how many posts BBQ you would have if you started 40 years ago .

And looking back and thinking what a wealth of electrical knowledge you gave to us .

Glad your here BBQ its nice i come online around 4 am before i go to work .

I work all day come home turn on the computer look at the ET posts sometimes ill post but then at times i skip a few days sometimes i skip a few months .

Its always good to know your here when we need help .:laughing::laughing:


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