# 2 ground rods



## MikeD

I live in New Orleans and the latest thing that inspectors are looking for is 2 ground rods (13mil) along with the water system bonded together(and gas)...Does anyone else have to do this?


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## 480sparky

MikeD said:


> I live in New Orleans and the latest thing that inspectors are looking for is 2 ground rods (13mil) along with the water system bonded together(and gas)...Does anyone else have to do this?


Is the water line plastic / poly?


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## chenley

Same her in west KY. Two ground rods 6 feet apart.


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## MikeD

no, whether its pvc or copper still 2 rods


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## 480sparky

MikeD said:


> no, whether its pvc or copper still 2 rods


Then it's either a POCO or local AHJ requirement.


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## MikeD

def. a orleans parish code


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## yankeewired

*supplemental electrode*

Yes, 2 8' grounding electrodes are required at least 6' apart required in MA for about 10 years now. They apply NEC 250.56 where resistance needs to be 25 ohms or less. Or you can use a underground metal waterpipe on the street side of meter and 1 rod.Requirements also allow under footing, rebar ect ., but I don't see those methods used in my area.Water meter always in the basement in Ma and typically 8' below grade. I have had ahj's still insist on 2 rods with copper watermain, their reasoning was most municipalities eventually change out water mains to plastic.


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## piette

Here in Wisconsin our state code requires two 8 ft. ground rods no matter what the water is. We have to bond any metal sections of water pipe and if flexible gas piping is run, we have to bond any sections no matter how small of black pipe that are in the run.

Jeff


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## frenchelectrican

If the OP mention 13 mil which it is a half inch rods 

But however in my area I am the same page as Piette due I am not far from his area.

Anyway seems most guys saying almost everywhere need two ground rods.

Merci,Marc


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## raider1

Due to the seismic requirements in my area, all footings are required to have at a minimum 2 #4 rebars run continious through the footings. So due to this we always have a UFER ground present so we must use that. So because there is no requirement to supplement a UFER ground we don't install ground rods anymore.

Chris


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## wirenut1110

raider1 said:


> Due to the seismic requirements in my area, all footings are required to have at a minimum 2 #4 rebars run continious through the footings. So due to this we always have a UFER ground present so we must use that. So because there is no requirement to supplement a UFER ground we don't install ground rods anymore.
> 
> Chris


I don't do new houses but, I thought that was replacing the grounding electrode system in new houses now. lol It looks like what you said.


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## nap

we follow the NEC with one or two adjustments.

a ground rod may not even be required in the building. One of the reasons most around here install it is because it is simpler to show the inspector the ground rod rather than the rebar bond, (Ufer) if used.

Unless you can prove ,25 ohms, you would need a second rod if that is the only electrode(s).

Building with plastic water supply. I was required to bond to the metal pipe inside the building. Gas lines are accepted as bonded by the circuit that feeds the appliance that the gas feeds but about hald the inspectors require a bond directly to the pipe.

Don;t forget to install bonding jumpers around the meter. I have been requrired to do it at the water (always) and sometimes around the gas meter. Seems to be a local requirement.


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## brian john

Is driving 2 rods that big a deal?

And driving 2 rods 6 feet apart is not gaining the most from your electrodes 8' rods should be (from an effective use standpoint) a minimum of 16 feet preferably more.


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## nap

No but it is money spent that does not need to be spent. In todays world, that $50 is a lot. You do this a few times on a small house and it could be the diff between getting the job and not getting the job.


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## leland

yankeewired said:


> Yes, 2 8' grounding electrodes are required at least 6' apart required in MA for about 10 years now. They apply NEC http://www.comcast.net/articles/news-general/20080711/Missing.Soldier/ where http://www.comcast.net/articles/news-general/20080711/Missing.Soldier/Or you can use a underground metal waterpipe on the street side of meter and 1 rod.Requirements also allow under footing, rebar ect ., but I don't see those methods used in my area.Water meter always in the basement in Ma and typically 8' below grade. I have had ahj's still insist on 2 rods with copper watermain, their reasoning was most municipalities eventually change out water mains to plastic.


 
25 ohms or less. The requirement for two rods... The easy way out. Not required at all, so long as you can prove 25 ohms or less (do you have the test equipment? And does the inspector know how to read /interprit the info you give them?):whistling2:.

PS: YANKEE Thank you for Posting the link !!!!
Thoughts and prayers for all !!!!!!!


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## brian john

> does the inspector know how to read /interpret the info you give them?):whistling2:.


While it is not quite this simple if the inspector cannot understand results of the test with 62% reading highlighted at 22.9 OHMS, well maybe he should retire.

By time the average contractor buys a test set has it calibrated every year and has someone trained to perform a three point test properly, do the paper work file the report. You could drive a lot of 8 foot rods.


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## Mountain Electrician

Here its a POCO standard...2 rods, 6 feet apart.


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## brian john

Not sure why they came up the 6' foot separation as the two rods are within the 'sphere of influence" of each rod. As I said, if the intent is to provide an efficient grounding electrode system 6' ain't the answer.


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## piette

brian john said:


> Not sure why they came up the 6' foot separation as the two rods are within the 'sphere of influence" of each rod. As I said, if the intent is to provide an efficient grounding electrode system 6' ain't the answer.


I was told that a ground rod needs 3' of clear dirt space to be an effective ground. Hence the 6'.

Jeff


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## brian john

Testing has shown that the effective distance should be twice the electrodes length for a more effective electrode.

http://www.baselinesystems.com/literature/biline/SurgeProtection.doc

Trying to find the links this has some info.


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## nap

brian john said:


> Not sure why they came up the 6' foot separation as the two rods are within the 'sphere of influence" of each rod. As I said, if the intent is to provide an efficient grounding electrode system 6' ain't the answer.


NEC states that 2 grounding electrodes must be a minimum of 6 feet apart.250.53(B).

I do agree with the sphere of influence statement but I believe theory is often lost on those that have learned by the: "Word of Mouth and Follow My Lead School of Electricity". They read the 6 foot rule in the code and that is what they apply.


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## richrock1605

In Michigan it's 2 ground rods minimum of 6 ft apart and a cold water ground


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## brian john

Rick why bother with 2 if the separation is 6' and yes I know the NEC and inspectors, but if they are serious about grounding safety two rods minimum of 16'.


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## nap

richrock1605 said:


> In Michigan it's 2 ground rods minimum of 6 ft apart and a cold water ground


Can you back that up because I can back up the fact it is not as you state. As a matter of fact, in Michigan, section 250 is accepted as written in the NEC except 250.118.

Now you may do things differently over in Deetroit but in the rest of the state, barring a local jurisdictional thing, NEC rules as stated above.


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## BackInTheHabit

2 Ground Rods
6 Feet Apart

Inspectors have required this since the 1999 code cycle.


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## nap

BackInTheHabit said:


> 2 Ground Rods
> 6 Feet Apart
> 
> Inspectors have required this since the 1999 code cycle.


first, I ask; inspectors or code?

and then, are you addressing the Michigan situation or Kentucky or some other state. 

If Michigan, I can assure you not all inspectors require 2 rods. I can provide a link to Michigan section 8 (which is their addenum to the NEC). There is nothing in that that would require anything other than what the NEC requires.

Second, I am a Mi res and have worked in Mi. I have never been required to install 2 rods. In many cases, I do not even need to install any rods. Rods, themselves are not a specific requirement in the NEC. They are used of other electrodes are not available.


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## BackInTheHabit

nap said:


> first, I ask; inspectors or code?
> 
> and then, are you addressing the Michigan situation or Kentucky or some other state.
> 
> If Michigan, I can assure you not all inspectors require 2 rods. I can provide a link to Michigan section 8 (which is their addenum to the NEC). There is nothing in that that would require anything other than what the NEC requires.
> 
> Second, I am a Mi res and have worked in Mi. I have never been required to install 2 rods. In many cases, I do not even need to install any rods. Rods, themselves are not a specific requirement in the NEC. They are used of other electrodes are not available.


1.) Inspectors

2.) Kentucky

This is in reference to residential. The electrical inspectors in Lexington all work for the same company which does all of Fayette County (Lexington). Other areas in the state electrical inspectors are independant from each other. Some of these set their own rules you have to follow.


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## Bkessler

I can verify that Petosky Michigan, Big Rapids Michigan, Kalamazoo Michigan and all of the Detroit suburbs require two ground rods 8' down 6' apart and I can also verify that califronia does not. and Huntington beach needs one stainless steel ground rod 8' down.


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## nap

Bkessler said:


> I can verify that Petosky Michigan, Big Rapids Michigan, Kalamazoo Michigan and all of the Detroit suburbs require two ground rods 8' down 6' apart and I can also verify that califronia does not. and Huntington beach needs one stainless steel ground rod 8' down.


If they do, they are a local jurisdictional issue.

but since you state you can verify it, let's see the proof.

and just to help you, here is a link to Kazoo's website concerning building codes. Look at chapter 9 section 99.

I cannot find Petoskey specifically but here is an application for an electrical permit for Emmet county. In it you will find that they require the electrical work to be installed per State Electrical Code.

If you have something more telling, please post it.

A search for Big Rapids seems to show they default to the county building department. Here is a Mecosta County electrical permit application. If you read it, you wil find that Mecosta County defers to the State Electrical Code.

I'm not looking through all of the Deetroit burbs. So, unless you have some other proof, we can assume you have simply forgotten the applicable codes for any specific area in Michigan.


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## Bkessler

My validation is the fact that I have had inspections in all those area's since they required two ground rods. And when it started to become a requirement I questioned it every chance I got because I thought it was a stupid requirement. Also I would love for you to prove that I don't have to use a ground rod in a home. Not by the code but where an inspector will let you not install one.


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## Bkessler

Besides nap I know you are very knowledgeable (and a pita) but it does seem like most of your work by your posts is commercial industrial. I think you may find if you talk to some more people who are doing houses anywhere in Michigan you will find they are using two ground rods. whether you can find it in writing or not.


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## brian john

Inspectors over dwell on 2 ground rods and yet ignore some obvious NEC issues including grounding. And the 2nd rod at 6' buys you VERY LITTLE.

So they have no clue what they are asking for just BOOK inspectors not knowledgeable members of our profession.

Look being an inspector is a tough job and they have to deal with some real "A" holes. I understand this but they have an obligation to know more than the NEC. 

Ever see a seminar come to town and the next thing you know they walk by a service with no main and flunk you on box fill cause the seminar by RACO concentrated on box fill?


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## Bkessler

I remember one inspector an old guy in Brighton Michigan tell me he thought it was stupid as well, but that is what his bosses told him to enforce. He Also mentioned if it were to do any good they would have to be further apart.


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## nap

Bkessler said:


> My validation is the fact that I have had inspections in all those area's since they required two ground rods. And when it started to become a requirement I questioned it every chance I got because I thought it was a stupid requirement. Also I would love for you to prove that I don't have to use a ground rod in a home. Not by the code but where an inspector will let you not install one.


*IF* one really wanted to argue the point, in Michigan, you can appeal the requirement to the state level. They may side with the inspector concerning an AHJ interpretation but they will not and cannot support a requirement self imposed by the AHJ without supporting code requirements.



I know of no Michigan code requirements that could remotely be interpreted as requiring two rods, or even one actually as long as there is a proper GE system in place.

Obviously because of the cost issue to appeal, the delay in receiving a CO for a building, and the inspector being forever pissed and may be in to proving his machismo and power and getting very picky with future inspections, it is often best to simply accept the requirement and go on with life.

as to getting proof a rod is actually not required by code and mandated by the inspector;

the inspector in my county is a bigger PITA than I am (if you can believe it) and is an ass when you ask him questions. I was working on my brothers house (same county as me) and asked the inspector about an install that is very well within the code. I simply wanted to be sure of how he saw things before spending $1k on material and having it not approved for some reason. He shot it down. I asked about an alternative design and he shot that down. I then simply asked him what he would allow. His response; "i'm not going to engineer your job for you". I have spoken to 2 inspectors since then about my proposed install. One was actually a city electrical inspector within the county involved. The other, totally unconnected. Both said either of my proposals were acceptable and could find no justification for this inspectors call. 

I don't have a lot of faith in this inspector nor the ability to even ask him a question. I guess when you make $150k/year compared to what an electrician makes, I guess it can give you a swollen head but I'll see what I can find out.

Now, one thing I will telll you about the second ground rod; if the inspector is not familiar with the geology of the area and know pretty much where 1 rod would be adequate, he should request a ground resistance test from you for 1 rod. The simple, cheap, fast and easy remedy is to simply install a second rod. Since there are no minimum resistance requirements at that point, he and you are safe. The requirement you have dealt with may simply be a bastardization of that rule and simply just felt that adding the second rod saves time, trouble, and money. Hard to tell without experiencing it myself.


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## Idaho Abe

*Ground rods*

In Idaho we require 2 ground rods 6 feet apart, ufer ground, metal water pipe ground , you may take your pick of any two of these methods.


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## Bkessler

Nap, I am not arguing that two ground rods is a nec requirement or an amendment in Michigan or any of it's locality's. But it shocks me that you have had an inspection and not had two ground rods because I have had to do it everywhere in Michigan. And I too am a pita as well, especially when it comes to inspectors critiqing my work. Now I live in Ca and there is other bs that is not in the code book they make you do here as well. I pick and choose my battle's and when your wiring spec homes 3-5 hours away from home you do what it takes to pass the inpection. My guess is your work is nice enough the inspector did not bother to look at your lack of a 2nd ground rod. Simply because your work is so nice and neat. And when inspectors see that they know they are dealing with a great electrician. But if you were to get out in different areas of Michigan you would find yourself either A) putting two ground rods in, or B) you could be the one to set the precident so we can all go tell the inspectors to f-off. Personally I hope *B. *


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## nap

I'm not doubting you have been told to install 2 rods. Like I said, I cannot find any support in NEC or MEC to support the requirement so unless there is a local jurisdictional thing that does require it, they cannot require you to do it.

As I also said*, IF* you really wanted to spend the time and effort to fight it at the state level, you are more than welcome to and will most likely win.

Often, winning the battle does not mean winning the war. That inspector could be pissed at you forever and make sure you know it at every subsequent inspection. I can guarantee I can find several code violations on just about any job I look at. Often they are quite minimal and ignored but if this guy has a hard on for you, I can assure you each and every one will get written up.

as well, I do not do resi, only commercial/industrial. The inspectors seem to have a different relationship with us, to some extent, than the resi guys. I don't know why. We use and must understand the same codes and justifications for those codes. Sometimes inspectors can simply be ****s.




> But if you were to get out in different areas of Michigan you would find yourself either A) putting two ground rods in, or B) you could be the one to set the precident so we can all go tell the inspectors to f-off. Personally I hope *B. *


I would love to go for B but the most prudent action is to bend over and install the second rod. It is easier, faster, and cheaper than the alternative of fighting it. As you said, you have to choose your battles and fighting for a $10 ground rod is not worth it.

I would definately push the guy to justify it and if I could not convinvce him otherwise, I would simply drive the second rod and be done with it.

Next time, I would try again.


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## JohnJ0906

Idaho Abe said:


> In Idaho we require 2 ground rods 6 feet apart, ufer ground, metal water pipe ground , you may take your pick of any two of these methods.


Abe, I know that metal water pipe (as an electrode) requires a supplemental electrode, (250.53(D)(2)) but why would I need a second electrode if I have a UFER?


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## nap

JohnJ0906 said:


> Abe, I know that metal water pipe (as an electrode) requires a supplemental electrode, (250.53(D)(2)) but why would I need a second electrode if I have a UFER?


by NEC you wouldn't. As with any jurisdiction, they have the right to apply whatever codes they wish to enact.

What is sounds like is happening in most areas are the inspectors may be unilaterally requiring 2 rods. If they see 2 rods, they know there are adequate electrodes in place. I believe it is either the AHJ believing they are on to something big or they are simply too lazy to look for the Ufer tie.


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## Bkessler

I am curious to which parts of the county are requiring a ufer ground these days.


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## nap

Bkessler said:


> I am curious to which parts of the county are requiring a ufer ground these days.


any that follow the NEC


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## Idaho Abe

*ground rods*

2 grounds and ufer are required by local code board.


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## nap

by code a Ufer MUST be included IF it is there. The only exception is on a pre-exisiting foundation where the rebar is not accessible.


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## nick

*2 rods*

in florida , i only do commercial work on most of our work the one line grounding shows 3 rods delta connection 30 feet apart and 30 feet down on each , cadweld connections and rods need to be copper coated 5/8 , most of our work needs 5 ohms or less and a 3 point fall of potential test they will not let us use the new clamp on testers and we have to show the engineer the test in the field , sometimes the electrical inspector if is a city job , cold water building steel and gas , the footer uffer has to be hit the steel hit by cadweld ,this is on every job . is not fun ! in residential i dont do but ive seen it as one rod ,if you do a trailer in florida its two rods with pvc water . one rod with a copper or metal water pipe no uffer ground is ever done here on homes we go by the nec only no local codes anymore it was a big change two years ago i think ? we were told no local codes will be inforced just nec . i guess no one reads the nec on homes in florida .


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## sparkyob

brian john said:


> Is driving 2 rods that big a deal?
> 
> And driving 2 rods 6 feet apart is not gaining the most from your electrodes 8' rods should be (from an effective use standpoint) a minimum of 16 feet preferably more.


That's interesting!!! It makes sense though.

By the way we are only required to drive one in Ohio.


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## eddy current

Canada = 2 rods *or one ground plate* CEC 10-702

Can you not use a ground plate in the US?
We usually use the ground plate because you only have to put it 600mm (2 feet) deep.


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## electricista

eddy current said:


> Canada = 2 rods *or one ground plate* CEC 10-702
> 
> Can you not use a ground plate in the US?
> We usually use the ground plate because you only have to put it 600mm (2 feet) deep.


Yes but we have to have a plate electrode at least 30 inches (750mm) below the surface


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## electricista

Bkessler said:


> I am curious to which parts of the county are requiring a ufer ground these days.


I wish they would start requiring them. Lately that's all I have been installing because it is far superior to 2 ground rods.


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## electricista

sparkyob said:


> That's interesting!!! It makes sense though.
> 
> By the way we are only required to drive one in Ohio.


Is this true or are the inspectors not pushing the NEC requirement?

NAP
I have reading your posts and I am confused by some of your statements. Am I correct in understanding that you believe the NEC only requires one ground rod?

I would agree with that if you get the required 25 ohms to ground otherwise two are required. Now I realize that if you have a ufer or other electrode you may not need the rod/s.


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## sparkyob

electricista said:


> Is this true or are the inspectors not pushing the NEC requirement?
> 
> NAP
> I have reading your posts and I am confused by some of your statements. Am I correct in understanding that you believe the NEC only requires one ground rod?
> 
> I would agree with that if you get the required 25 ohms to ground otherwise two are required. Now I realize that if you have a ufer or other electrode you may not need the rod/s.


We typically do not have to because the resistance usually ok. Only a handful of times I have had to. Must be the soil conditions in my region.


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## electricista

sparkyob said:


> We typically do not have to because the resistance usually ok. Only a handful of times I have had to. Must be the soil conditions in my region.


Wow if we get 80 ohms around here we are good and that's with 2 rods.


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## nap

electricista said:


> Is this true or are the inspectors not pushing the NEC requirement?
> 
> NAP
> I have reading your posts and I am confused by some of your statements. Am I correct in understanding that you believe the NEC only requires one ground rod?
> 
> I would agree with that if you get the required 25 ohms to ground otherwise two are required. Now I realize that if you have a ufer or other electrode you may not need the rod/s.


first, code requires all available electrodes in their list to be utilized, if available. the list is; building steel (specific requirements to make it usable), water pipe (same thing), Ufer ground (specific requriements for a proper electrode), That is all that is required if any of them are available. If none of those 3 are available, then a supplemental electrode is required. A rod, pipe, or plate electrode has the unique distinction of, if used singly, to allow less than 25 ohms resistance. If the resistance is greater, then a second supplemental electrode of any type (with no spec of resistance required) is all that is needed.



make anymore sense now?


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## walkerj

I have never seen two rods on a home. 
I have never seen a UFER on a home.
All UG water is plastic.
Everything seems to still work fine:001_huh:


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## electricista

nap said:


> first, code requires all available electrodes in their list to be utilized, if available. the list is; building steel (specific requirements to make it usable), water pipe (same thing), Ufer ground (specific requriements for a proper electrode), That is all that is required if any of them are available. If none of those 3 are available, then a supplemental electrode is required. A rod, pipe, or plate electrode has the unique distinction of, if used singly, to allow less than 25 ohms resistance. If the resistance is greater, then a second supplemental electrode of any type (with no spec of resistance required) is all that is needed.
> 
> make anymore sense now?


I don't agree , unless I am misreading your statement. I see no articles to back up what you say. Check art. 250.53(D)(2) and explain your statement about an underground water pipe not needing an additional electrode. I agree it may not need rods if you use a ufer but if no ufer is available the rods or other supplemental electrode must be used.

(D) Metal Underground Water Pipe. Where used as a grounding electrode, metal underground water pipe shall meet the requirements of 250.53(D)(1) and (D)(2).
(1) Continuity. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters or filtering devices and similar equipment.
(2) Supplemental Electrode Required. *A metal underground water pipe shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) through (A)(8). *Where the supplemental electrode is a rod, pipe, or plate type, it shall comply with 250.56. The supplemental electrode shall be permitted to be bonded to the grounding electrode conductor, the grounded service-entrance conductor, the nonflexible grounded service raceway, or any grounded service enclosure.
Exception: The supplemental electrode shall be permitted to be bonded to the interior metal water piping at any convenient point as covered in 250.52(A)(1), Exception.


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## brian john

walkerj said:


> I have never seen two rods on a home.
> I have never seen a UFER on a home.
> All UG water is plastic.
> Everything seems to still work fine:001_huh:


It will work fine till you get that lightning strike.


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## kbsparky

electricista said:


> Wow if we get 80 ohms around here we are good and that's with 2 rods.


And how many ohms did you measure with only one rod? Bet it wasn't much different .... :blink:


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## electricista

kbsparky said:


> And how many ohms did you measure with only one rod? Bet it wasn't much different .... :blink:


I bet you are correct. Adding a second rod is not very useful but I didn't write the code. There are many things in the code that are questionable at best.

Now put in a ufer and you can almost guarantee getting less than 25 ohms.


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## ralph

Your right about that. I swear, I could wire a house with lamp cord down here, and pass any rough inspection all day long , but if I miss a nail plate, they will catch it. Heck , ive failed inspections before for bonding the rebar in the slab. They had no idea what I was doing, and after I expalined it,he wanted me to take it out. Siad it wasnt good for the concrete:blink:.
I guess its something that wont change for a while. Alot of municipalities are cutting back these days


brian john said:


> Inspectors over dwell on 2 ground rods and yet ignore some obvious NEC issues including grounding. And the 2nd rod at 6' buys you VERY LITTLE.
> 
> So they have no clue what they are asking for just BOOK inspectors not knowledgeable members of our profession.
> 
> Look being an inspector is a tough job and they have to deal with some real "A" holes. I understand this but they have an obligation to know more than the NEC.
> 
> Ever see a seminar come to town and the next thing you know they walk by a service with no main and flunk you on box fill cause the seminar by RACO concentrated on box fill?


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## electricista

brian john said:


> It will work fine till you get that lightning strike.



Good point, perhaps the only reason for a ground rod is for that lightning strike. The less ohms you get the better protection you have from the strike.

Let's not forget that a rod will do nothing to clear a fault. You can drive a ground rod into the earth and get 10 ohms ( if you could you are fortunate) then run a 20 amp wire off a breaker directly to the rod. This will not trip the breaker.


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## nap

electricista said:


> I don't agree , unless I am misreading your statement. I see no articles to back up what you say. Check art. 250.53(D)(2) and explain your statement about an underground water pipe not needing an additional electrode. I agree it may not need rods if you use a ufer but if no ufer is available the rods or other supplemental electrode must be used.
> .


I stand corrected on the water pipe electrode.


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## volty

*Water pipe + single electrode + 2nd rod?*

What do you think about:



> 250.53(D)(2) Supplemental Electrode Required. A metal underground water pipe shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) through (A)(8). Where the supplemental electrode is a rod, pipe, or plate type, it shall comply with 250.56. . .


And:



> 250.56 A *single* electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of 25 ohms or less shall be augmented by one additional electrode . . .


I don't think this means *two* rods in *addition *to the water pipe, no matter the suggestion of (D)(2). If there is a metal underground water pipe used as a grounding *electrode*, then the rod is not a *single electrode*.:blink:

I feel that the second rod should only be (potentially) required if there are no other electrodes.

Whatchya think?


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## kbsparky

> ...I feel that the second rod should only be (potentially) required if there are no other electrodes.


Persactly.


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## electricista

volty said:


> I don't think this means *two* rods in *addition *to the water pipe, no matter the suggestion of (D)(2). If there is a metal underground water pipe used as a grounding *electrode*, then the rod is not a *single electrode*.:blink:


I think you are misreading art. 250.56. That articles pertains to rod, pipe or plate electrodes, not water pipe. It is specifcally talking about electrodes in 250.52(A)(4) thru (A)(8).



> I feel that the second rod should only be (potentially) required if there are no other electrodes.
> Whatchya think?


What it *should require* and what it *does require *are 2 different animals. It is quite clear in art. 250.53(D)(2) where it tells us to supplement the water pipe with another electrode in 250.52 (A)(2) thru (A)(8). You can read it as loosely as you want but it states what it states and it is quite clear.


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## nap

electricista said:


> What it *should require* and what it *does require *are 2 different animals. It is quite clear in art. 250.53(D)(2) where it tells us to supplement the water pipe with another electrode in 250.52 (A)(2) thru (A)(8). You can read it as loosely as you want but it states what it states and it is quite clear.


I missed it and electrista is correct.

It does not require any specific resistance reading on that _one_ supplemental electrode but it is required.


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## electricista

nap said:


> I missed it and electrista is correct.
> 
> It does not require any specific resistance reading on that _one_ supplemental electrode but it is required.


I appreciate the support however, art 250.53(D)(2) does specify a resistance reading. --- It states:


> *It shall comply with 250.56
> *





> 250.56 Resistance of Rod, Pipe, and Plate Electrodes.
> A single electrode consisting of a rod, pipe, or plate that does not have a resistance to ground of *25 ohms or less shall be augmented by one additional electrode of any of the types specified by 250.52(A)(4) through (A)(8).* Where multiple rod, pipe, or plate electrodes are installed to meet the requirements of this section, they shall not be less than 1.8 m (6 ft) apart.
> FPN: The paralleling efficiency of rods longer than 2.5 m (8 ft) is improved by spacing greater than 1.8 m (6 ft).


If you cannot get 25 ohms with one rod then you would need another rod or one of the other electrodes stated.


----------



## volty

electricista said:


> If you cannot get 25 ohms with one rod then you would need another rod or one of the other electrodes stated.


But the second paragraph of 250.58 states that:


> Two or more grounding electrodes that are bonded together shall be considered as a single grounding electrode conductor in this sense.


They are speaking of grounding the supply system, and the enclosures as the different things that should use the same electrode, in that section.

Personally, I wish we had to put in two or more rods, because the plumber that replaces the metal water pipe with non-metallic doesn't tell the building owner to have an electrician check the grounding. 

But I still need to be convinced that if there is a metal water pipe, a metal building frame, a concrete-encased electrode, *and *a driven ground rod, that a test to ground of 26 ohms on the rod itself *requires* a second one to be installed.

Of course we probably all agree that if there is *only* a concrete-encased electrode, we are done.


----------



## electricista

volty said:


> But I still need to be convinced that if there is a metal water pipe, a metal building frame, a concrete-encased electrode, *and *a driven ground rod, that a test to ground of 26 ohms on the rod itself *requires* a second one to be installed.
> 
> Of course we probably all agree that if there is *only* a concrete-encased electrode, we are done.


These two paragraphs are in direct contradiction to each other. First statement seems to suggest you need all the electrodes. As your second paragraph suggests if there is a CEE no rod is required. If you have a metal water pipe only as an electrode then a rod must be driven. If that rod alone measures 25 ohms or less then we are done. If not another rod is needed and it doesn't matter if we get 25 ohms or not. Odd? Yes.

Around here no one even tests for ohms because we know we won't get 25 ohms so we just use 2 rods. Lately I have been using the CEE since it is a better electrode then the rods.


----------



## volty

electricista said:


> These two paragraphs are in direct contradiction to each other. First statement seems to suggest you need all the electrodes. As your second paragraph suggests if there is a CEE no rod is required. If you have a metal water pipe only as an electrode then a rod must be driven. If that rod alone measures 25 ohms or less then we are done. If not another rod is needed and it doesn't matter if we get 25 ohms or not. Odd? Yes.
> 
> Around here no one even tests for ohms because we know we won't get 25 ohms so we just use 2 rods. Lately I have been using the CEE since it is a better electrode then the rods.


But where is the exception? 250.53(D) says:


> Where used as *a* grounding electrode, metal underground water pipe shall meet the requirements of 250.53(D)(1) and (D)(2).


(D)(2) requres the supplemental electrode. If that is a rod, pipe, or plate, then 250.56.

So if water pipe, and ufer, and one rod exist, does 250.56 still apply? If the rod is a *single* electrode when supplementing the water pipe electrode, isn't it still a *single* electrode per 250.56 when a CEE exists?

I mean, if a driven rod exists, is it *always* subject to the 25 ohm rule, or only when is comprises the entirerity of the grounding electrode system itself?


----------



## nap

electricista said:


> I appreciate the support however, art 250.53(D)(2) does specify a resistance reading. --- It states:
> 
> 
> 
> If you cannot get 25 ohms with one rod then you would need another rod or one of the other electrodes stated.


a rod, pipe, or plate electrode is not the only acceptable electrode when supplementing the water pipe. 

Now if you are using a rod, pipe, or plate electrode, I still read it that the resistance is not considered due to the verbiage in that section: "a _*single*_ electrode consisting of a rod, pipe, plate...etc" 

the rod, pipe, plate is no longer a single electrode but part of a grounding electrode system by virtue of the fact the water pipe is also part of the system.


In essence, the water pipe and the rod fulfill the secondary part of each respective electrodes requirements which is; with the water pipe, that it is supplemented with an additional electrode and with the rod, if greater than 25 ohms resistance, it be supplemented with an additional electrode of some type and then no specific resistance limitation is required.


----------



## electricista

volty said:


> But where is the exception? 250.53(D) says:
> (D)(2) requres the supplemental electrode. If that is a rod, pipe, or plate, then 250.56.
> 
> So if water pipe, and ufer, and one rod exist, does 250.56 still apply? If the rod is a *single* electrode when supplementing the water pipe electrode, isn't it still a *single* electrode per 250.56 when a CEE exists?
> 
> I mean, if a driven rod exists, is it *always* subject to the 25 ohm rule, or only when is comprises the entirerity of the grounding electrode system itself?


Okay we have a miscommunication here. If a ufer is installed then it is pointless to install a ground rod. If you do install a ground rod with a ufer present then , of course, two rods would not be necessary since one isn't necessary in that case. Sorry I am not sure where I inferred that but trust me I never thought that 2 rods were necessary if a ufer is present.

a rod, pipe, or plate electrode is not the only acceptable electrode when supplementing the water pipe. 

Now if you are using a rod, pipe, or plate electrode, I still read it that the resistance is not considered due to the verbiage in that section: "a _*single*_ electrode consisting of a rod, pipe, plate...etc" 

the rod, pipe, plate is no longer a single electrode but part of a grounding electrode system by virtue of the fact the water pipe is also part of the system.




Nap said:


> In essence, the water pipe and the rod fulfill the secondary part of each respective electrodes requirements which is; with the water pipe, that it is supplemented with an additional electrode and with the rod, if greater than 25 ohms resistance, it be supplemented with an additional electrode of some type and then no specific resistance limitation is required.


I am not following. If there is a water pipe that is your primary electrode then you have to supplement with any of the methods in 250. 52(A)2-(A)(8). If you choose the building steel as your supplemental electrode you can stop there. If you choose a ufer as your supplemental electrode you can stop there. If you choose a ground ring then go no further. If, you decide to use a ground rod or pipe or plate electrode then you must add a second rod, pipe or plate if the first one does not achieve 25 ohms. 

There are also other listed electrodes and other local metal underground systems or structures that may be used. If they are used then no need to add rods or go any further.


----------



## volty

electricista said:


> Okay we have a miscommunication here. If a ufer is installed then it is pointless to install a ground rod. If you do install a ground rod with a ufer present then , of course, two rods would not be necessary since one isn't necessary in that case. Sorry I am not sure where I inferred that but trust me I never thought that 2 rods were necessary if a ufer is present.


Agreed, the rod is not a single electrode.


> a rod, pipe, or plate electrode is not the only acceptable electrode when supplementing the water pipe.
> 
> Now if you are using a rod, pipe, or plate electrode, I still read it that the resistance is not considered due to the verbiage in that section: "a _*single*_ electrode consisting of a rod, pipe, plate...etc"
> 
> the rod, pipe, plate is no longer a single electrode but part of a grounding electrode system by virtue of the fact the water pipe is also part of the system.


More agreement



> I am not following. If there is a water pipe that is your primary electrode then you have to supplement with any of the methods in 250. 52(A)2-(A)(8). If you choose the building steel as your supplemental electrode you can stop there. If you choose a ufer as your supplemental electrode you can stop there. If you choose a ground ring then go no further. If, you decide to use a ground rod or pipe or plate electrode then you must add a second rod, pipe or plate if the first one does not achieve 25 ohms.


Why? I thought that we agreed that the rod wasn't a single electrode in these cases.
250.56 Doesn't care what the other electrode(s) are, if rod, pipe, or plate, then minimum distances exist, but it could be ufer, building steel, water pipe, ground ring.

If we consider that the 25 ohm rule applies to the ground rod when the water pipe exists, then mustn't it *always* exist when one rod and the water pipe exist? No exception is given if other types also exist.
250.56 doesn't mention water pipes.

Electricista, thanks for working through this with me, I'm not completely comfortable with either position. I always drive two rods if no other electrodes exist, usually one if metal underground water pipe, but two if the budget allows. You've got a good grasp of this and it is nice to consider all the subtleties of these sections.

I think it all comes down to 250.53(D)(2), ". . . . it shall comply with 250.56."; 
and 250.56 ". . . single electrode consisting of a . . ."


----------



## preacher

*Ground rod*

While I was in Iraq working on the bonding and grounding issues we had a ground rod tester to to check ground rod resistance. Worked like a clamp on amp meter. Checked 100's of ground rod and none were even close to 25 ohms. Most were 2-3 ohms, in the sand. Found that interesting.


----------



## knothole

When TN adopted the 2008 code they now require a bond to the rebar in the footer or 20 ft. of #4 bare copper in the concrete. If this is not done or the builder forgets or you do a service change and can't meet this requirement, they will allow you to drive 2 ground rods 6 ft apart and bond them to the meterbase with a piece of #4 bare copper buried 30" deep.

Done one today.:laughing:


----------



## preacher

*Ground rod*

I spoke to the inspector here and he said if you can prove less than 25 ohms on a ground rod only one is needed. Cheaper to drive 2 rods than to buy a $800.00 ground rod tester.


----------



## electricista

knothole said:


> When TN adopted the 2008 code they now require a bond to the rebar in the footer or 20 ft. of #4 bare copper in the concrete. If this is not done or the builder forgets or you do a service change and can't meet this requirement, they will allow you to drive 2 ground rods 6 ft apart and bond them to the meterbase with a piece of #4 bare copper buried 30" deep.


Why do you need a #4 to the rod? and why does it need to be buried 30" deep? Is this punishment for not installing the CEE  or is this a local amendment?


----------



## lectricboy

I live in Northeastern KY, and that's the way we do it here.


----------



## Bkessler

preacher said:


> I spoke to the inspector here and he said if you can prove less than 25 ohms on a ground rod only one is needed. Cheaper to drive 2 rods than to buy a $800.00 ground rod tester.



That is what I have been told by the inpsectors as well, And the use of #4 solid is so it does not have to be protected from physical damage.


----------



## jayare813

yep here in florida 2 rods min 6ft apart if rock bottom is encountered u may dig a ditch and lay them on the ground....dont know exactly the specs for the laying on ground though should be in article 250


----------



## electricista

Bkessler said:


> And the use of #4 solid is so it does not have to be protected from physical damage.


I understand that a #4 does not need protection but an inspector has no right to order a #4 and make you bury it 30" as stated above. I am trying to understand that logic.

Around here #6 unprotected is the norm to a rod. No protection is enforced.
I must say I have never seen #6 bare copper that was damaged. Don't quite get that rule.


----------



## bobelectric

Like good little Marines,we just say "Sir,Yes Sir."Just to get an approval and a $check$.


----------



## caliwest

How would both the 2 rods, and the cold water be bonded? Diasy chained? Or Could i put 3 clamps on one rod? One ground going to the panel, the other to the other ground rod, and the third to the cold water pipe?


----------



## Archania

For one, check with the POCO and see what they want. I know around me, if its a 100amp service, 1 ground rod. 200amp, 2 ground rods (6' apart). However, they can be all on the same ground wire. Go from the rods, to the water pipes, to the gas pipe and then to the panel and you should be good.


----------



## raider1

> I know around me, if its a 100amp service, 1 ground rod. 200amp, 2 ground rods (6' apart).


The NEC doesn't care about the amperage of the service, if you are installing a ground rod(s) as the only grounding electrode you must either show that there is no more than 25 ohms with a single rod or you install a second ground rod.

Take a look at 250.56.

Chris


----------



## Zog

preacher said:


> While I was in Iraq working on the bonding and grounding issues we had a ground rod tester to to check ground rod resistance. Worked like a clamp on amp meter. Checked 100's of ground rod and none were even close to 25 ohms. Most were 2-3 ohms, in the sand. Found that interesting.


No way you had 2-3 Ohms in the sand with 1 rod. 1st off a clamp on ground tester wont work with 1 rod, ther eis no return path. The fewer rods you have the less accurate it is. But your low reading most likely was due to the meter being connected to a ground loop rather than a lead to a grounding electrode. It will invariably provide a very low resistance for the ground loop which has no relevance to the actual ground resistance. This is the most common misuse if clamp on ground testers. 

The only accurate way to test a ground rod is a 3 or 4 point fall of potential test. Special equipment and training is required. This is not practical for this application, checking a single rod <25 ohms, hence the easier solution of just driving a 2nd rod.


----------



## Archania

raider1 said:


> The NEC doesn't care about the amperage of the service, if you are installing a ground rod(s) as the only grounding electrode you must either show that there is no more than 25 ohms with a single rod or you install a second ground rod.
> 
> Take a look at 250.56.
> 
> I realize that, but if the city/POCO says you have to have 2 or else they will not hook up the power, what do you do?


----------



## 480sparky

Archania said:


> Take a look at 250.56.
> 
> I realize that, but if the city/POCO says you have to have 2 or else they will not hook up the power, what do you do?


 
Then they must have a local amendment to the NEC. Legal, as long as due process was followed.


----------



## Archania

Yea, it's kind of weird here in Palo Alto, because they "own" their own utilities, so the city is basically judge, jury and executioner when it comes to the power...


----------



## NevadaBoy

raider1 said:


> Due to the seismic requirements in my area, all footings are required to have at a minimum 2 #4 rebars run continious through the footings. So due to this we always have a UFER ground present so we must use that. So because there is no requirement to supplement a UFER ground we don't install ground rods anymore.
> 
> Chris


Same here. UFER is the answer...


----------



## drsparky

Zog said:


> No way you had 2-3 Ohms in the sand with 1 rod. 1st off a clamp on ground tester wont work with 1 rod, ther eis no return path. The fewer rods you have the less accurate it is. But your low reading most likely was due to the meter being connected to a ground loop rather than a lead to a grounding electrode. It will invariably provide a very low resistance for the ground loop which has no relevance to the actual ground resistance. This is the most common misuse if clamp on ground testers.
> 
> The only accurate way to test a ground rod is a 3 or 4 point fall of potential test. Special equipment and training is required. This is not practical for this application, checking a single rod <25 ohms, hence the easier solution of just driving a 2nd rod.


I don't agree with you. A clamp on ground rod tester is very accurate. I really did not understand your explanation of one rod and ground loops; you don't need a return path. Can you elaborate? A clamp on ground rod tester uses a high frequency signal and measures the forward to reverse power ratio to determine resistance.


----------



## Zog

drsparky said:


> I don't agree with you. A clamp on ground rod tester is very accurate.[/qupte]
> 
> How do you know? There is no way a clamp on ground reading can be proffed, which is why is not an acceptable method by any recognized standard. A 3 or 4 point FOP test when done right provides proof that the measurement is accurate.
> 
> 
> 
> drsparky said:
> 
> 
> 
> I
> I really did not understand your explanation of one rod and ground loops; you don't need a return path. Can you elaborate?
> 
> 
> 
> It is finding a return path. you just dont know what that path is, which is why the results cannot be relied on. A FOP test, sets up a predetermined return path so you actually know what you are measuring.
> 
> Most clamp on ground testers have been discontinued, considered obsolete, because they just dont work well enough for many applications.
> 
> Read this, and this.
> 
> http://www.netaworld.org/files/ItemFileA909.pdf
> 
> http://www.netaworld.org/files/ItemFileA940.pdf
Click to expand...


----------



## drsparky

Here is an article by the same author a year later. I hate to be cynical but he may have changed his mind now that Megger sells a clamp on type.

http://ecmweb.com/grounding/electric_ground_testing_techniques/
Like anything if is done properly it works fine. I Googled around and could not find anyone specifically banning the use of clamp on type. Florida Power and Light approves there use at nuclear power plants. Also a quick check of Google and I found many tests confirming accuracy. Also many manufactures, they aren’t cheap. 

Has anyone else out there had problems with clamp on type?:001_huh:


----------



## Zog

drsparky said:


> Here is an article by the same author a year later. I hate to be cynical but he may have changed his mind now that Megger sells a clamp on type.


I know Jeff, and have had this discussion with him at length. They (Megger) have flip flopped again, and obsoleted thier clamp on testers. They now sell a new system that combines the clamp on tester with some 3 point principles, they call it ART (Attached Rod Technique)

http://www.megger.com/common/documents/ETARTar.pdf

http://www.megger.com/us/story/Index.php?ID=125




drsparky said:


> t find anyone specifically banning the use of clamp on type. Florida Power and Light approves there use at nuclear power plants.


We do most of the testing at all of FP&L's nuclear plants, I will pull the spec and send it to you. You wont find a spec banning clamp on testing, but they will require the testing to be done IAW NETA or ANSI testing standards that does not allow for clamp on methods, only 3 point FOP and 4 point (Werner method) 




drsparky said:


> Has anyone else out there had problems with clamp on type?:001_huh:


Of course no one will know they have a problem, if they just assume the readings are accurate. Only one person on this forum (That I know of) may have some data (Brian John, answer the phone)


----------



## drsparky

This is probably the most interesting thread I have been on. I am learning from every post. In was working for Miller Electric in south Florida few years ago and I had to barrow the ground tester from the crew at Point St Lucie so I could use on another project. It was the first time I used one and thought it was the cats pajamas. Home Depot had just bought the Cox lumber chain and I had to evaluated the electrical and communications of the lumber yards and stores. Anyway this is a very interesting subject and I am glad that someone has a detail background. This is why I am her to learn, debate, and maybe pass on my knowledge or experience. I will go back to researching more on this subject, but I got to tell you I like the clamp on.

Chuck


----------



## brian john

drsparky said:


> , but I got to tell you I like the clamp on.
> 
> Chuck


Everybody does BUT IN MY EXPIERENCE not a reliable, and not accepted by many firms that require ground testing with specifications.

First and foremost downstream grounds skew the results. Having completed countless testing on services I can tell you there are you better than 90% of the facilities out there have downstream ground issues. Assuming that this meter is acceptable for 10% of the jobs there are 90% of the electricians misapplying the instrument.

When they simplify testing every Tom, **** and Harry think I can do that. Look at IR as camera came down in price everyone is doing them, how many are decent at it FEW, very FEW.

Any body can buy any test equipment and I can teach them to use the equipment, BUT UNDERSTANDING what they are doing and what the results mean are different.

I lost a job to an ENERGY MANAGEMENT SPECIALTY FIRM, their sales point was they are engineers, worst GD reports I have ever seen, a frigging joke. The only good part of this I now have the job at my price to CORRECTLY do the job. These engineers had their own IR and recorders but hired Snake Electric cause after all they were cheap and any electrician can do it.


----------



## bdashley

*grounding in nova scotia , canada*

Hey guys
Just a note from a canadian electrician here. We can still ground to street copper here without a rod.Ground for 125and 200 amp is done with #6awg minimum, bare or green. If no city copper line is available we go to rods. They must be 10 feet long minimum and 10 feet apart. A small task to do in our rocky soil ! All gas piping and copper water systems are bonded with #6 copper only.
Anyway once again thats our world
Have a good safe work day guys
Take care:thumbup:


----------



## drsparky

Well I'm convinced. I will go back to the 3 or 4 point fall of potential test. I was not aware of the problems with the clamp on type. I guess it was too good to be true. 
Back in the day I would set up long hall HF radios and antennas. If we did not have a ground plane they would not work. One time we set up in Egypt in the sand, I drove in a star ground and nothing. Had the fire department dump a tanker of water and bam. All the radios would start howling with traffic and the VSWR dropped down. The clamp on type also uses a high frequency signal so I assumed I was revisiting a variation of an old concept.

Chuck


----------



## preacher

All I can tell you is the grounding electrode conductor was removed from the rod and the meter put on the rod. These were made by Fluke and instructions were followed to the t. If you clamped the meter on the grounding electrode itself you would get a higher reading, but still low. Inevitably, if the reading was high it was usually a loose ground clamp. These meters had a calibration scale and if they were off scale they were sent to Fluke to re-calibrate. They were purchased by the government and the testing was always done by two different electricians and verified by a quality control person. That's all I know about it other than they paid me big bucks to do the tests.


----------



## Old Spark

In my area we install a copper ufer wire in the footing before concrete is poured. This wire either is attached to concrete 3" dobbies or hung from the rebar near the bottom by tie wraps. The copper will last a lot longer that steel rebar in some areas. We use 5/8" ground rods for residential service upgrades, have not heard of the requirement for two except in areas of known pour soil conditions where grounding is questionable with one.


----------



## Bob Badger

David Channell said:


> have not heard of the requirement for two except in areas of known pour soil conditions where grounding is questionable with one.



See 250.56


----------



## Old Spark

I realize that you must have 25 ohms or less resistance, what I should have said is one ground rod usually does have less that 25 ohms and we have only had to test for that on government jobs. We tend to have moist clay type soil here and is usually makes for a good ground. But most of our jobs are for systems of 400 amps or more and the AHJ's are not comfortable with ground rods on this size services, so we install the 1/0 or larger copper ufer grounds installed in the footings. We have had to install up to four 3/4" x 10' ground rods at a phone company though. It was run to a 1/4" x 8"x 24" copper plate that the phone employees use to ground their systems. They were looking for less that 5 ohms of resistance.


----------



## Zog

sparkyob said:


> We typically do not have to because the resistance usually ok. Only a handful of times I have had to. Must be the soil conditions in my region.


I have tested several ground systems in Cleveland and the soil conditions are horrible, how are you testing these?


----------



## Zog

Never mind, already discussed


----------



## brian john

David Channell said:


> I realize that you must have 25 ohms or less resistance.


 
You do not have to have 25 ohms or less, what you are suppose to have is one rod 25 ohms or less or add a second rod and it does not matter if the reading is infinity with two rods.




> what I should have said is one ground rod usually does have less that 25 ohms and we have only had to test for that on government jobs.


Typically (location dependent) one rod does not have 25 ohms are less in my experience. And I have tested electrodes in quite a few states.




> We tend to have moist clay type soil here and are usually makes for a good ground. But most of our jobs are for systems of 400 amps or more and the AHJ's are not comfortable with ground rods on this size services,


 
Unless there is a local amendment what to heck do they care? and what difference does it make whether the service is 100 amps or 4000 amps?


----------



## bobkat

After reading through this thread I am a bit surprised that no-one has challenged the basis for the 25 ohm requirement. I did and ended up doing an exhausing search for the genesis and reasoning for the 25 ohm rule. NFPA found that it was introduced in the 1917 edition on the NEC but could find no substantiation for the rule. I have queried numerous electrical engineers with no success.

So....... I did what all good electricians do, I submitted a code change proposal to eleiminate the rule in the 2011 edition. And......... So the code panel elected to accept my proposal "in concept". What they actually did was recommend to change 250.56 to require 2 rods unless <25 ohms can be demonstrated (bummer). I don't know what the final outcome of this article will be but I'm thinking we will be driving 2 rods for some time to come.


----------



## RIVETER

*Two ground rods*



bobkat said:


> After reading through this thread I am a bit surprised that no-one has challenged the basis for the 25 ohm requirement. I did and ended up doing an exhausing search for the genesis and reasoning for the 25 ohm rule. NFPA found that it was introduced in the 1917 edition on the NEC but could find no substantiation for the rule. I have queried numerous electrical engineers with no success.
> 
> So....... I did what all good electricians do, I submitted a code change proposal to eleiminate the rule in the 2011 edition. And......... So the code panel elected to accept my proposal "in concept". What they actually did was recommend to change 250.56 to require 2 rods unless <25 ohms can be demonstrated (bummer). I don't know what the final outcome of this article will be but I'm thinking we will be driving 2 rods for some time to come.


I guess that I will never understand why many people will argue about a known thing. The NEC is the bare minimum that you must do. All good electricians should want to install a service that is the safest that it can be. Two rods don't sound extreme to me...in any case. A ground rod is installed for the purpose of dissipating any abberant voltage impressed on an electrictrical system. If you are not satisfied with the OHM reading, you should try again...After a couple of tries, then possibly just satisfy the code...and hope for an indirect HIT.


----------



## Rudeboy

RIVETER said:


> I guess that I will never understand why many people will argue about a known thing. The NEC is the bare minimum that you must do. All good electricians should want to install a service that is the safest that it can be. Two rods don't sound extreme to me...in any case. A ground rod is installed for the purpose of dissipating any abberant voltage impressed on an electrictrical system. If you are not satisfied with the OHM reading, you should try again...After a couple of tries, then possibly just satisfy the code...and hope for an indirect HIT.


Exactly, drive a couple of ground rods oh what, ten feet apart, twenty if it makes you happy. It takes like twenty minutes. If you have a ufer, f it.
What's the big deal?


----------



## macmikeman

RIVETER said:


> I guess that I will never understand why many people will argue about a known thing. The NEC is the bare minimum that you must do. All good electricians should want to install a service that is the safest that it can be. Two rods don't sound extreme to me...in any case. *A ground rod is installed for the purpose of dissipating any abberant voltage impressed on an electrictrical system.* If you are not satisfied with the OHM reading, you should try again...After a couple of tries, then possibly just satisfy the code...and hope for an indirect HIT.



Where are these electrons dissipating to? I hope they dissipate their way back to the source transformer, cause if they don't then they don't dissipate to anywhere period.


----------



## macmikeman

We have on local inspector who if you have plastic water lines to the structure requires two rods driven- "they have to be less than six feet apart"...... 
I had two about 15 feet apart. He would not let it go. So I just put one more in the middle of the two, to keep him happy and went home and kicked the dog..... well felt like it anyway.


----------



## brian john

macmikeman said:


> We have on local inspector who if you have plastic water lines to the structure requires two rods driven- "they have to be less than six feet apart"......
> I had two about 15 feet apart. He would not let it go. So I just put one more in the middle of the two, to keep him happy and went home and kicked the dog..... well felt like it anyway.


He is an idiot.


----------



## brian john

RIVETER said:


> I guess that I will never understand why many people will argue about a known thing. The NEC is the bare minimum that you must do. All good electricians should want to install a service that is the safest that it can be. Two rods don't sound extreme to me...in any case. A ground rod is installed for the purpose of dissipating any abberant voltage impressed on an electrictrical system. If you are not satisfied with the OHM reading, you should try again...After a couple of tries, then possibly just satisfy the code...and hope for an indirect HIT.



Because some of us know and others just guess at it. Which park do you fall in?


If safety is your goal and you feel a low resistance is necessary, then you need to test and get your electrodes below some value. If not you have NO ARGUMENT regarding safety.

I say a BIG THANK YOU to bobkat, keep at it.


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## Bob Badger

bobkat said:


> After reading through this thread I am a bit surprised that no-one has challenged the basis for the 25 ohm requirement. I did and ended up doing an exhausting search for the genesis and reasoning for the 25 ohm rule. NFPA found that it was introduced in the 1917 edition on the NEC but could find no substantiation for the rule. I have queried numerous electrical engineers with no success.
> 
> So....... I did what all good electricians do, I submitted a code change proposal to eliminate the rule in the 2011 edition. And......... So the code panel elected to accept my proposal "in concept". What they actually did was recommend to change 250.56 to require 2 rods unless <25 ohms can be demonstrated (bummer). I don't know what the final outcome of this article will be but I'm thinking we will be driving 2 rods for some time to come.





RIVETER said:


> I guess that I will never understand why many people will argue about a known thing.


What is it that you _know_ about the 25 ohm requimment for one rod?

Even the NFPA can not say why 25 ohms is safe and 26 ohms is unsafe.

And if there are no rods involved there is no 25 ohm requiment at all.

Bobkat is doing the right thing in my opinion. 





> The NEC is the bare minimum that you must do.


Yes it is, but the bare minium is not unsafe and belive it or not you do the bare miniumum as well quite often.

What size wire do you generally use with 20 amp breakers? 12 AWG? that is the bare minimum in most cases.

When you run PVC conduit do you run one EGC or two EGCs?

One EGC is the bare minimum.




> A ground rod is installed for the purpose of dissipating any abberant voltage impressed on an electrictrical system.


Well you must be talking lightning as that is the only source that 'dissapates' into the earth. And when your talking lighting the diffreance beteen 5 ohms and 100 ohms is not going to make a darn bit of difference.




> If you are not satisfied with the OHM reading, you should try again...After a couple of tries, then possibly just satisfy the code...and hope for an indirect HIT.


The moment you drive a second rod you have satisfied the code requiment even if the rods still have a restance far in excces of 25.


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## brian john

Bob Badger said:


> What is it that you _know_ about the 25 ohm requimment for one rod?
> 
> Even the NFPA can not say why 25 ohms is safe and 26 ohms is unsafe.
> 
> And if there are no rods involved there is no 25 ohm requiment at all.
> 
> Bobkat is doing the right thing in my opinion.
> 
> 
> 
> 
> 
> Yes it is, but the bare minium is not unsafe and belive it or not you do the bare miniumum as well quite often.
> 
> What size wire do you generally use with 20 amp breakers? 12 AWG? that is the bare minimum in most cases.
> 
> When you run PVC conduit do you run one EGC or two EGCs?
> 
> One EGC is the bare minimum.
> 
> 
> 
> 
> Well you must be talking lightning as that is the only source that 'dissapates' into the earth. And when your talking lighting the diffreance beteen 5 ohms and 100 ohms is not going to make a darn bit of difference.
> 
> 
> 
> 
> The moment you drive a second rod you have satisfied the code requiment even if the rods still have a restance far in excces of 25.



And someone DARED to question your education?


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## bobkat

Believe me gang. My intent in writing a code change proposal is not to weaken the NEC or try to make my life easier. I would just want the CMP to explain the rule or defend it in some scientific or rational way. 

If their is some physical or scientific rational for the magic 25 ohm requirement I have yet to hear it. If their is some rational then the requirement should be met, not disposed of by driving a 2nd rod.

Then there is the issue of when the rod is driven. In many parts of the country the ground resistance changes with the seasons. If you measure the ground resistance in the spring with damp soil it may pass; but it might fail in the late fall when the soil is dry.

Way too many questions than answers in my little mind.


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## Old Spark

Sorry to change the subject a little bit, but I could not find the thread where someone challenged the need for a larger grounding rod or ufer with the larger amp systems. I had left my code book at work so I could not answer him. Now I have my code book and the answer is 250.66. This is what is inforced here in Calif. I thought it was the National Electrical Code. I don't see where many commercial jobs would get by with a ground rod or two. I do admit that 250.52 A3 does confuse the issue to me. The AHJ here just go by the table 250.66 and so does the electrical engineers designing the plans.
David


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## Bob Badger

David Channell said:


> Sorry to change the subject a little bit, but I could not find the thread where someone challenged the need for a larger grounding rod or ufer with the larger amp systems. I had left my code book at work so I could not answer him. Now I have my code book and the answer is 250.66. This is what is inforced here in Calif. I thought it was the National Electrical Code. I don't see where many commercial jobs would get by with a ground rod or two. I do admit that 250.52 A3 does confuse the issue to me. The AHJ here just go by the table 250.66 and so does the electrical engineers designing the plans.
> David


Under the NEC you could have a 4,000 amp 480 volt service and if no electrodes where present one or two ground rods installed and connected with 6 AWG would be NEC compliant.


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## brian john

David Channell said:


> Sorry to change the subject a little bit, but I could not find the thread where someone challenged the need for a larger grounding rod or ufer with the larger amp systems. I had left my code book at work so I could not answer him. Now I have my code book and the answer is 250.66. This is what is inforced here in Calif. I thought it was the National Electrical Code. I don't see where many commercial jobs would get by with a ground rod or two. I do admit that 250.52 A3 does confuse the issue to me. The AHJ here just go by the table 250.66 and so does the electrical engineers designing the plans.
> David


Table 250.66 has nothing to do with driven electrodes see 250.66 (A) for driven electrodes, 250.88 (B) for ufers and 50.66 (6) for ground rings.

We all go by the table for what the table was designed for BUT if the AHJ and engineers are following the table as you say (this table requires larger electrodes based on service size), then all of CA is nuttier than we back east ever thought was possible.


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## Old Spark

Well I'll tell you, the guys who steel copper here in Calif. love the rules we have, because they get a lot more copper by stealing our ufer grounds. We have to try to hide them somehow until concrete is poured and a switch board is sitting on top and locked up.


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## acelectricohio

*2 Ground Rod Code*

I find that the only reason the code came up with this one has to do with more upselling for the rod manufacturer. I live and wok in Cleveland. The earth out here is rich in minerals and is always a good source for grounding. We are forgetting the fact that ground rods are SUPPLEMENTAL and not the main source of grounding; they are lightning protection! But, in any case, the 25 ohm rule I do not argue. The 25 ohm reading comes from both the main water ground and your ground rod....not JUST the ground rod. No electrical contractor in their right mind is going to pay $2600 for a ground tester (at least living up north) in order to appease the inspector. They probably wouldn't argue and pay the extra 13 bucks and labor to install the rod (and my arm hurts less writing this then actually stomping that piece of metal). And even if you CAN prove that there is 25 ohms or less, they will come back and say "different soil conditions during different times of the year"!
I am trying to put a dent into the ground rod manufacturers pockets, so here it goes.
Install a 10 amp breaker on your panel while you are dressing it. Install a no. 6 thhn cu conductor to the ground bus. After complete installation, remove your neutral from the panel and turn the power on to the 100 amp main and then the 10 amp. If the breaker trips, your done. If it doesnt trip, check ampacity. 5 amp and higher, you passed. Less than 5 ohms, you failed. If the inspector says "different soil conditions...", call him in 6 months for another reinspection. Coming back to that home, you can reaquaint yourself with the customer and probably get another job. Ohms law folks, do the math. 
This is an attempt to stop the manufacturers from writing the code. Pass it on. 
ONCE AGAIN, THERE IS NOTHING ILLEGAL IN THIS INSTALL. BASIC OHMS LAW PRINCIPALS APPLY AND WE ARE USING ALL UL LISTED MATERIALS TO TEST THE EQUPIMENT.
Send me a reply on your comments. Thank you.


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## backstay

acelectricohio said:


> I find that the only reason the code came up with this one has to do with more upselling for the rod manufacturer. I live and wok in Cleveland. The earth out here is rich in minerals and is always a good source for grounding. We are forgetting the fact that ground rods are SUPPLEMENTAL and not the main source of grounding; they are lightning protection! But, in any case, the 25 ohm rule I do not argue. The 25 ohm reading comes from both the main water ground and your ground rod....not JUST the ground rod. No electrical contractor in their right mind is going to pay $2600 for a ground tester (at least living up north) in order to appease the inspector. They probably wouldn't argue and pay the extra 13 bucks and labor to install the rod (and my arm hurts less writing this then actually stomping that piece of metal). And even if you CAN prove that there is 25 ohms or less, they will come back and say "different soil conditions during different times of the year"!
> I am trying to put a dent into the ground rod manufacturers pockets, so here it goes.
> Install a 10 amp breaker on your panel while you are dressing it. Install a no. 6 thhn cu conductor to the ground bus. After complete installation, remove your neutral from the panel and turn the power on to the 100 amp main and then the 10 amp. If the breaker trips, your done. If it doesnt trip, check ampacity. 5 amp and higher, you passed. Less than 5 ohms, you failed. If the inspector says "different soil conditions...", call him in 6 months for another reinspection. Coming back to that home, you can reaquaint yourself with the customer and probably get another job. Ohms law folks, do the math.
> This is an attempt to stop the manufacturers from writing the code. Pass it on.
> ONCE AGAIN, THERE IS NOTHING ILLEGAL IN THIS INSTALL. BASIC OHMS LAW PRINCIPALS APPLY AND WE ARE USING ALL UL LISTED MATERIALS TO TEST THE EQUPIMENT.
> Send me a reply on your comments. Thank you.


You've spilled the beans! Just need to use a 5 amp fuse, If it pops you're good. That way you can leave the amp meter at home.


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## Dennis Alwon

acelectricohio said:


> Install a 10 amp breaker on your panel while you are dressing it. Install a no. 6 thhn cu conductor to the ground bus. After complete installation, remove your neutral from the panel and turn the power on to the 100 amp main and then the 10 amp. If the breaker trips, your done. If it doesnt trip, check ampacity. 5 amp and higher, you passed. Less than 5 ohms, you failed. If the inspector says "different soil conditions...", call him in 6 months for another reinspection. Coming back to that home, you can reaquaint yourself with the customer and probably get another job. Ohms law folks, do the math.
> This is an attempt to stop the manufacturers from writing the code. Pass it on.


First off I want to say *do not do this* as it can be dangerous. I can't believe you would even suggest it without warning. I agree with alot of the post, however there are times when the ground rod is the main electrode. You live in the city but many of us don't see copper lines in the ground anymore and unless you install a CEE you are dependent on the rods for lightning protection and surges. Truth be told , in most cases, they are worthless anyway. Drive the two rods and let the manufacturer and yourself make money.

You would need 6 ohms to trip a 20 amp breaker and even then it would work for some time. 6 ohms is unrealistic in many areas of the country.

We had a guy here in NC selling and installing chemical ground rods. At $800 cost per rod then installation etc he said he could guarantee 10-15 ohms. I installed a CEE and got 13 ohms.... and it cost less then $125.00. Of course that reading will change over periods of wet and dry times.


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## electricmanscott

Dennis Alwon said:


> First off I want to say *do not do this* as it can be dangerous. I can't believe you would even suggest it without warning..


Screw 'em, survival of the fittest. :thumbsup:

BTW
Old thread alert....


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## Dennis Alwon

electricmanscott said:


> Screw 'em, survival of the fittest. :thumbsup:
> 
> BTW
> Old thread alert....



One of the MH members drove a ground rod out in a field and tried to trip the breaker he tied it to. He was very careful and stayed away from the ground that was being energized. He was amazed it didn't trip. He didn't believe us so he had to try it. 

Problem is ohio guy here had a setup that was a bit precarious to say the least.

BTW, what are you doing home I thought you had a new job or are you playing on company time.


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## electricmanscott

Dennis Alwon said:


> BTW, what are you doing home I thought you had a new job or are you playing on company time.


 
Lunch time. :thumbup:

Just spliied my Sunny D all over the desk.


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## BBQ

electricmanscott said:


> Just spliied my Sunny D all over the desk.



Lifes a real bitch! :laughing:


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## ColoradoMaster3768

brian john said:


> Not sure why they came up the 6' foot separation as the two rods are within the 'sphere of influence" of each rod. As I said, if the intent is to provide an efficient grounding electrode system 6' ain't the answer.


 
I would guess the idea behind the 6' separation is to mitigate potential liability—and it's an easy reference to the _NEC_.


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## ColoradoMaster3768

Dennis Alwon said:


> ...Of course that reading will change over periods of wet and dry times.


I did a resistance experiment several years ago simply using a glass of salted-tap water filled with ice. Although I don't remember what the resistance measurements were, I do remember that as the water warmed up, the resistance went down. This implies that soil resistivity may very well increase as the temperature drops. This surprised me, as had always thought the opposite was true.


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## brian john

ColoradoMaster3768 said:


> I did a resistance experiment several years ago simply using a glass of salted-tap water filled with ice. Although I don't remember what the resistance measurements were, I do remember that as the water warmed up, the resistance went down. This implies that soil resistivity may very well increase as the temperature drops. This surprised me, as had always thought the opposite was true.


Google it! Frozen ground is a lousy conductor, just as dry soil and certain soil types


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## RIVETER

ColoradoMaster3768 said:


> I did a resistance experiment several years ago simply using a glass of salted-tap water filled with ice. Although I don't remember what the resistance measurements were, I do remember that as the water warmed up, the resistance went down. This implies that soil resistivity may very well increase as the temperature drops. This surprised me, as had always thought the opposite was true.


It is good that you care enough about grounding to do extra experiments. You will find out a lot of information for yourself and not have to rely on just what you read. Keep it up. I might add that lightning just doesn't jump from a cloud in hopes that it MIGHT find some place to go as it reaches earth. The difference of potential is there before it leaves the cloud. Our hope is to give it a path if it chooses our point on the earth.


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## McClary’s Electrical

brian john said:


> He is an idiot.





electricmanscott said:


> BTW
> Old thread alert....


 

Yeah, ^^^^^^^that's the Brian we're missing:whistling2:


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## zodizzle

here in wa they told me today that i could put 2 eight foot rods in a 2 foot trench at least one foot apart and it works for code, is that true?


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## Dennis Alwon

zodizzle said:


> here in wa they told me today that i could put 2 eight foot rods in a 2 foot trench at least one foot apart and it works for code, is that true?


 I believe the trench needs to be 30" deep and 6' apart.


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## Cletis

*Cliff*



brian john said:


> Testing has shown that the effective distance should be twice the electrodes length for a more effective electrode.
> 
> http://www.baselinesystems.com/literature/biline/SurgeProtection.doc
> 
> Trying to find the links this has some info.


Bad link .Can you Cliff Note or summarize the difference of setting rods 6' apart v.s. 12' and the implications????


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## Amish Electrician

Looks like a 'refresher course' is needed.

There are two matters to consider: code changes and the engineering data.

The engineering data can be found in the "American Electricians' Handbook." They have the graphs that show the how the effectiveness of a ground rod is affected by different factors, such as length of the rod or the distance between rods.

Neither of those graphs is a straight line. They're pretty severe curves.

Since they're curves, you can't pick one point and say 'this is it.' You can see, though, where making big changes will make very little difference.

For the length of a ground rod, that point of diminishing returns is somewhere between an 8ft. rod and a 10ft. rod. Make the rod longer, and it's not much better. Contrast this with a, say, 4ft rod, where adding even an inch makes a big difference.

Ditto for the distance between two rods. Moving the second rod from 12" away to 13" away makes a huge difference; increasing the distance past 6ft makes very little improvement. Brian Johns remark, early in this thread, that the rods need to be sixteen feet apart is simply not supported by the data. The data does, though, suggest where the code requirement came from.

Now ... as for the NEC ....

Prior to the latest edition, code language siad one rod was enough unless there was more than 25 ohms resistance between the rod and the earth. In 2011, the language was changed.

Now, code says two rods are needed, unless you can prove that one is enough. The burden has changed.

The 25 ohm figure is significant. Let's say you have a code-allowed 25 ohm ground rod. How much current can flow through a 25 ohm circuit? Well, at 120 volts, Ohm's law tells us 4.8 amps. 

4.8 amps. Think about that. None of our household circuits use less than a 15-A breaker. So, even with a code-legal ground, there is simply no way that even a direct-to-earth fault will ever trip a breaker.

So ... what good is the ground rod? Well, Mike Holt concluded that the ground rod has nothing to do with clearing faults; the only role it could play was to facilitate the return of static electricity (lightning) to the earth from which it came.


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## Zog

Cletis said:


> Bad link .Can you Cliff Note or summarize the difference of setting rods 6' apart v.s. 12' and the implications????


Spacing makes little difference for just 2 rods. See figure 13 here
http://www.biddlemegger.com/biddle-ug/GettingDownToEarth-MC.pdf

This is a great reference for anything related to ground system testing.


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## raider1

Amish Electrician said:


> Looks like a 'refresher course' is needed.
> 
> There are two matters to consider: code changes and the engineering data.
> 
> The engineering data can be found in the "American Electricians' Handbook." They have the graphs that show the how the effectiveness of a ground rod is affected by different factors, such as length of the rod or the distance between rods.
> 
> Neither of those graphs is a straight line. They're pretty severe curves.
> 
> Since they're curves, you can't pick one point and say 'this is it.' You can see, though, where making big changes will make very little difference.
> 
> For the length of a ground rod, that point of diminishing returns is somewhere between an 8ft. rod and a 10ft. rod. Make the rod longer, and it's not much better. Contrast this with a, say, 4ft rod, where adding even an inch makes a big difference.
> 
> Ditto for the distance between two rods. Moving the second rod from 12" away to 13" away makes a huge difference; increasing the distance past 6ft makes very little improvement. Brian Johns remark, early in this thread, that the rods need to be sixteen feet apart is simply not supported by the data. The data does, though, suggest where the code requirement came from.
> 
> Now ... as for the NEC ....
> 
> Prior to the latest edition, code language siad one rod was enough unless there was more than 25 ohms resistance between the rod and the earth. In 2011, the language was changed.
> 
> Now, code says two rods are needed, unless you can prove that one is enough. The burden has changed.
> 
> The 25 ohm figure is significant. Let's say you have a code-allowed 25 ohm ground rod. How much current can flow through a 25 ohm circuit? Well, at 120 volts, Ohm's law tells us 4.8 amps.
> 
> 4.8 amps. Think about that. None of our household circuits use less than a 15-A breaker. So, even with a code-legal ground, there is simply no way that even a direct-to-earth fault will ever trip a breaker.
> 
> So ... what good is the ground rod? Well, Mike Holt concluded that the ground rod has nothing to do with clearing faults; the only role it could play was to facilitate the return of static electricity (lightning) to the earth from which it came.


250.4(A)(1) in the NEC tells us what the purpose of the ground rod is.



> (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.


You will notice that nowhere in that section does it ever state that the connection to the earth is to provide a fault current path to clear an overcurrent protective device.

In fact if you continue to 250.4(A)(5) "Effective ground fault current path" you will see that it specifically states that the earth shall not be considered as an effective ground fault current path.

Chris


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## Amish Electrician

Thanks for your chiming in, Chris.

Your code citation aside, it's amazing the number of posts you can find on electrical forums where folks think that the ground rod has something to do with breakers tripping. It was these posts, as well as some comments in this thread, that convinced me that a 'primer' was needed.

While code citations can be nice, it's also nice to understand the 'why,' and where things come from. Eight foot ground rods, at least six feet apart, are not specifications that came about at random. 

You'll find some old-timers with memorise of driving in rods that were 50ft, or even longer. You'll find references to special salt mixes that were added to the ground- all in an attempt to get the resistance below 25 ohms. 

Ahh, those were the days, the 'twilight zone' between when Mr. Ufer invented his electrode, and the NEC accepted it a quarter-century later.

Also, code requirements (and language) do change over time. That's what caused the OP to post in the first place.


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## raider1

Amish Electrician said:


> Thanks for your chiming in, Chris.
> 
> Your code citation aside, it's amazing the number of posts you can find on electrical forums where folks think that the ground rod has something to do with breakers tripping. It was these posts, as well as some comments in this thread, that convinced me that a 'primer' was needed.
> 
> While code citations can be nice, it's also nice to understand the 'why,' and where things come from. Eight foot ground rods, at least six feet apart, are not specifications that came about at random.
> 
> You'll find some old-timers with memorise of driving in rods that were 50ft, or even longer. You'll find references to special salt mixes that were added to the ground- all in an attempt to get the resistance below 25 ohms.
> 
> Ahh, those were the days, the 'twilight zone' between when Mr. Ufer invented his electrode, and the NEC accepted it a quarter-century later.
> 
> Also, code requirements (and language) do change over time. That's what caused the OP to post in the first place.


I agree, it is a very common misconception that the grounding electrode system is used to clear a ground fault.

Chris


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## Zog

raider1 said:


> I agree, it is a very common misconception that the grounding electrode system is used to clear a ground fault.
> 
> Chris


Well it is, just not in LV systems


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## raider1

Zog said:


> Well it is, just not in LV systems


Your right, I should have clarified that the earth is used for a fault current path for some utility medium and high voltage systems.

But for systems 600 volt and below the NEC prohibits using the earth for an effective fault current path.:thumbsup:

Chris


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## LightsOn81

We are required to have the 2 ground rods 6ft. Apart and to bond the gas lines but on every job where the man throws a fit about us not doing it, my super goes in and tells them there is no way we are tying any gas pipe into any electric system and if they want to it's on them. We will usually drive individual ground rods for any outdoor gas equipment and isolate it from the buildings electrical system


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## raider1

LightsOn81 said:


> We are required to have the 2 ground rods 6ft. Apart and* to bond the gas lines but on every job where the man throws a fit about us not doing it, my super goes in and tells them there is no way we are tying any gas pipe into any electric system and if they want to it's on them.*


250.104(B) requires that metal gas piping be bonded, the equipment grounding conductor of the circuit likely to energize the gas piping is permitted to be used to bond the gas line. Keep in mind that if I have a gas appliance like a furnace or gas range there is already a bonding connection due to the EGC run to the gas appliance.




> We will usually drive individual ground rods for any outdoor gas equipment and isolate it from the buildings electrical system


There is absolutely no requirement to drive a ground rod at outdoor gas equipment. The bonding requirements in 250.104 deal with the gas piping system not gas equipment. If the gas equipment is also served by an electrical source then it most likely will require that the equipment be connected to an equipment grounding conductor.

Chris


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## bluecap

*2 Ground Rods ??*

I guess in the county of Santa Barbara Ca its required but not in the city.

The 1st time i had to do it was in 2006 it was a 400 amp meter service 1/0 bonding wire to copper water utility within 5' of entrance to building ( but not if plumbing was done in new const. and pex was used ) then loop metal piping system @ water heater ( hot, cold, gas ) and 1/0 grounding electrode conductor from 2 5/8 x 8' rods spaced 6' apart or prove less then 25 ohms with what i think is a mega-meter i remember that from the navy but that test is complicated and the tool is expensive its easier to just drive another rod.
i just did a 200 amp meter service in the county Jan 2013 and guess what same deal drive another rod and just interconnect the rods with a single conductor to panel
its something about supplemental grounding kinda over kill 
but the inspector let it slide he didnt have me drive another rod


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## Amish Electrician

2 ground rodsin New Orleans?

Quit crying. You're built on mud, for Pete's sake; the rods practically fall into the earth. You have to drive to Western Arkansas to see a rock.


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## bluecap

Nice perception you have, actually its not as soft as ya might think, i didnt say it was at the beach:thumbsup:


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