# Residential grounding of services



## gmbjr (Mar 25, 2010)

I just had an inspector require a second ground rod 8' from the first on a 200A service. The installation is in an area I have worked in and had services inspected and passed for 28 years, my own neighborhood. There is, as always, a properly installed correctly sized #4 ground to the main 3/4" water line coming into the house and also the obligatory 5/8" groundrod. This has been the norm here for a million years, and as recently as a month ago.

I cannot find any requirememnt saying a 3rd grounding electrode is necessary in this circumstance, and the guy also wants the ground rod driven all the way into the dirt with nothing above grade, where we have always left a few inches above ground to see the mechanical connection....

Very unusual request for this area which is not sandy or loose soil. There is no earth to ground resistance issue. I wonder where these guys get their ideas from sometimes.


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## NolaTigaBait (Oct 19, 2008)

Could be a local deal...They require that in Orleans parish as well...By code, all you need is one ground rod to supplement the water electrode...If you have more than 25 ohms , then you are supposed to add till you get it...I've never seen anyone actually do this though. I think also, the inspecters want to justify their job.


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## 3phase (Jan 16, 2007)

Gmb, sounds like my inspector. He wants 2 rods no matter what and the top had better be below grade. He wants them below grade to eliminate someone stepping or falling on the end (impalement).


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## gmbjr (Mar 25, 2010)

I think the guy misunderstands the code. As I noted, I have been doing services in this area for 28 years, we dont have sandy or loose gravelly soil. In fact the soil is loamy and beyond about 12" very dense clay. You really have to work to drive the rod into it. Just a month ago an identical installation passed no problem(as it should).


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## raider1 (Jan 22, 2007)

Actually the inspector is correct.

If you have a metal water pipe as a grounding electrode you must supplement it with another electrode of the type specified in 250.52(A)(2) through 250.52(A)(8). Where the supplemental electrode is a ground rod it must comply with 250.56, which would require that the ground rod have a resistance of 25 ohms or less or be augmented with another electrode.

Take a look at 250.53(D)(2)



> (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.


Chris


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## william1978 (Sep 21, 2008)

Inspectors here will let you get by with one ground rod if you can show them that it is below 25 ohms. Everyone just puts two rods and be done with it.


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## BuzzKill (Oct 27, 2008)

how is he right? The OP has the water pipe bond and ground rod? The code doesn't say you need two rods (unless the 25 ohm thing).


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## william1978 (Sep 21, 2008)

BuzzKill said:


> how is he right? The OP has the water pipe bond and ground rod? The code doesn't say you need two rods (unless the 25 ohm thing).


 You would have to prove the 25 ohms.


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## nitro71 (Sep 17, 2009)

gmbjr said:


> I think the guy misunderstands the code. As I noted, I have been doing services in this area for 28 years, we dont have sandy or loose gravelly soil. In fact the soil is loamy and beyond about 12" very dense clay. You really have to work to drive the rod into it. Just a month ago an identical installation passed no problem(as it should).


 
Sounds like your inspector is spot on actually:

Ground rods should be flush or below grade unless protected, 250.53(G).

If you don't want to test your one ground rod for resistance then you need an additional rod, 250.56.

You should be thankful you have clay and not rocks down there. You should see if you can talk your GC into letting you install concrete encased electrodes instead of driving ground rods.


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## raider1 (Jan 22, 2007)

BuzzKill said:


> how is he right? The OP has the water pipe bond and ground rod? The code doesn't say you need two rods (unless the 25 ohm thing).


The code requires that a ground rod that supplements a water pipe to have 25 ohms or less or be augmented by a second rod, I don't believe the OPer mentioned that he proved the rod had a resistance of 25 Ohms or less.

Chris


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## BuzzKill (Oct 27, 2008)

I guess we need to find out if the inspector actually tested for resistance of the rod.


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## william1978 (Sep 21, 2008)

BuzzKill said:


> I guess we need to find out if the inspector actually tested for resistance of the rod.


 I can answer that one. No he isn't going to test it. If the contractor wants to use one rod he needs to prove that it has less than 25ohms.


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## BuzzKill (Oct 27, 2008)

what a gyp; I think it should be up to the inspector to test.


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## raider1 (Jan 22, 2007)

BuzzKill said:


> what a gyp; I think it should be up to the inspector to test.


Why, you as the contractor need to be able to verify that the rod meets code with the 25 Ohms or less or you have to augment it. 

Chris


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## william1978 (Sep 21, 2008)

BuzzKill said:


> what a gyp; I think it should be up to the inspector to test.


Well around here they will let you drive one rod, but you will have to meet the inspector and show him on your meter that it is correct. Someone can drive a ton of ground rods for what that meter cost. This meter cost about $1400. http://us.fluke.com/fluke/usen/Earth-Ground/Fluke-1630.htm?PID=56021


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## gmbjr (Mar 25, 2010)

it wouldnt be so bad if the identical installation a month ago in the same township passed(and have passed for 28 years). It is getting to where you don't know what arbitrary idea the inspector will come up with on any given job. And the jerkoffs won't come out in advance and tell you exactly what they want beforehand either. Not like in Philly where you can call the underwriter out and have him tell you exactly what he wants under a given circumstance. If the inspector wants things done a certain way then they should put it in writing in the twp code so we can see it and change our methods accordingly.


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## william1978 (Sep 21, 2008)

gmbjr said:


> it wouldnt be so bad if the identical installation a month ago in the same township passed(and have passed for 28 years). It is getting to where you don't know what arbitrary idea the inspector will come up with on any given job. And the jerkoffs won't come out in advance and tell you exactly what they want beforehand either. Not like in Philly where you can call the underwriter out and have him tell you exactly what he wants under a given circumstance. If the inspector wants things done a certain way then they should put it in writing in the twp code so we can see it and change our methods accordingly.


I don't understand why you have heart burn on this this change took place back in the 1999 code 11 years ago. Whoever has been inspecting your work in the past is who you should be upset with. And on the back of the business cards here say that they do not engineer or design your jobs.


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## sparks134 (Jan 30, 2009)

How far do you have to bury that wire going to the other ground rod?


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## william1978 (Sep 21, 2008)

sparks134 said:


> How far do you have to bury that wire going to the other ground rod?


 Around here we have to use #4 bare so we only need to get it below grade a couple inches.


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## sparks134 (Jan 30, 2009)

william1978 said:


> Around here we have to use #4 bare so we only need to get it below grade a couple inches.


Cab you use lets say THHN/THWN? IDK I never had to drive a second rod!


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## I_get_shocked (Apr 6, 2009)

sparks134 said:


> Cab you use lets say THHN/THWN? IDK I never had to drive a second rod!


if its bare what does the insulation matter? We normally use #6 THHN and drive 2 8' rods 6 ft apart and keep the #6 continuous and bury a few inches below grade


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## william1978 (Sep 21, 2008)

sparks134 said:


> Cab you use lets say THHN/THWN? IDK I never had to drive a second rod!


 Yea you can use it. Just everyone uses bare. That is all I have seen around here.


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## Zog (Apr 15, 2009)

william1978 said:


> Well around here they will let you drive one rod, but you will have to meet the inspector and show him on your meter that it is correct. Someone can drive a ton of ground rods for what that meter cost. This meter cost about $1400. http://us.fluke.com/fluke/usen/Earth-Ground/Fluke-1630.htm?PID=56021


Not many specs allow for a clamp on measurement as proof. Clamp on measurements are limited in thier applications and are done incorrectly more often than correctly, best to do a 3 point fall of potential if you need to test your ground resistance, but in most cases it is not worth the time and effort (Unless you have a specific spec that needs to be met) and drive a 2nd rod. 

Before everyone gets on my case, here is why: 

1. How it works: It sets up a current in the ground circuit by magnetic induction. It then measures the current and voltage drop to determine the resistance. Ideally the ground being measured is a ground rod in a system of many other ground rods.

2. Pitfalls and Tips: Like any other instrument it has limitations. Please read the manual. There are a few real important items to notice like...

a. There MUST BE AT LEAST TWO EARTH GROUNDS (ground rods) in the ground circuit for it to work properly. If you try to measure one ground rod, it will read OL (out of range). The meter's limit is 1200 OHMS, after that it will read OL. OL means that the ground circuit is open or the ground resistance is over 1200 ohms. A tactical ground should be far less than 1200 ohms, more like 25 ohms. 

b. Also, the fewer ground rods in the circuit, the less accurate it is. This is because a clamp on ground tester uses other ground rods in the system (added in parallel) as a reference. If there are only two ground rods, the reading you are getting is the SUM of the two resistances. It is not possible to tell (with this instrument) if one ground rod has a greater resistance than the other when there are only two ground rods in the circuit. 

c. There is a warning on the meter that reads R<1 OHM. If this is on, the reading is inaccurate and you are measuring a closed circuit conductive loop. 

d. There is a warning on the meter that reads "NOISE". If this is on, there is over 50V or over 5A on the ground circuit. There is probably an electrical fault condition if this is true - power down the system and render it safe until the problem can be corrected. 

e. Another pitfall is that the conductive contacts in the jaws get dirty. Wipe them frequently with a SOFT lint-free cloth. If the contacts are dirty, the meter will indicate "jaws open" or possibly read OL.


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## william1978 (Sep 21, 2008)

Zog have you done any ground testing in this area? If you have did any of them read 25 ohms or less?


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## william1978 (Sep 21, 2008)

Zog said:


> Not many specs allow for a clamp on measurement as proof. Clamp on measurements are limited in thier applications and are done incorrectly more often than correctly, best to do a 3 point fall of potential if you need to test your ground resistance, but in most cases it is not worth the time and effort (Unless you have a specific spec that needs to be met) and drive a 2nd rod.
> 
> Before everyone gets on my case, here is why:
> 
> ...


 Sure sounds like driving that second rod would be so much easier.


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## Zog (Apr 15, 2009)

william1978 said:


> Sure sounds like driving that second rod would be so much easier.


Yep, even if you have all the right test equipment a proper 3pt FOR test takes at at least an hour, another rod is cheaper. In this area, I would not expect a single rod to ever be <25 ohms so you end up driving a 2nd rod anyways.


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## Zog (Apr 15, 2009)

william1978 said:


> Zog have you done any ground testing in this area? If you have did any of them read 25 ohms or less?


Done lots of groud testing in this area but not an application like this, we test ground systems that either need to be <5 ohms or <1 ohm (Sometimes less), depending on the application and spec.


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## william1978 (Sep 21, 2008)

Zog said:


> Yep, even if you have all the right test equipment a proper 3pt FOR test takes at at least an hour, another rod is cheaper. In this area, I would not expect a single rod to ever be <25 ohms so you end up driving a 2nd rod anyways.


 When that code change took place back in 99 I know they tested the application that we are talking about and couldn't get it anywhere in Mecklenburg County.


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## gmbjr (Mar 25, 2010)

okay, so I'll buy the part where the inspector assumes the resistance isn't going to be low enough so he is enacting a stronger standard in his jurisdiction. No biggie. 

Heres a new question though:

Some of you are saying simply drive the 2nd rod and connect the two in series. The code section has a little note mentioning paralleling. The Fluke website shows parallel. My personal opinion is it should either be paralleled or make a grid by connecting the 2 rods and running back to the panel.....can anyone show an illustration of which the code requires?:001_huh:


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## gmbjr (Mar 25, 2010)

now I find this....which is contradicting what i found on the Fluke website and the little note in the NEC...

http://www.illustratedhomeonline.com/details.php?gid=68&pid=2436


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## sparks134 (Jan 30, 2009)

I_get_shocked said:


> if its bare what does the insulation matter? We normally use #6 THHN and drive 2 8' rods 6 ft apart and keep the #6 continuous and bury a few inches below grade


 Only a few inches below grade? :001_huh:


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## electricmanscott (Feb 11, 2010)

gmbjr said:


> it wouldnt be so bad if the identical installation a month ago in the same township passed(and have passed for 28 years). It is getting to where you don't know what arbitrary idea the inspector will come up with on any given job. And the jerkoffs won't come out in advance and tell you exactly what they want beforehand either. Not like in Philly where you can call the underwriter out and have him tell you exactly what he wants under a given circumstance. If the inspector wants things done a certain way then they should put it in writing in the twp code so we can see it and change our methods accordingly.


I think your anger is misdirected. If you just follow the code you wouldn't have to worry about what the "jerkoffs" want. If I was at the point where I needed inspectors to come out and show me what they want befor I did a job I'd consider going back to school.

The inspector is 100 percent correct and you should be happy that you finally have an inspector with a hint of a clue after all these years. The fact that you have been doing it wrong all this time is not the inspectors problem.


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## electricmanscott (Feb 11, 2010)

gmbjr said:


> okay, so I'll buy the part where the inspector assumes the resistance isn't going to be low enough so he is enacting a stronger standard in his jurisdiction. No biggie.
> :


What code do you work under?

If it's the NEC than this statement shows you are not getting what everyone is telling you.


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## gmbjr (Mar 25, 2010)

electricmanscott said:


> I think your anger is misdirected. If you just follow the code you wouldn't have to worry about what the "jerkoffs" want. If I was at the point where I needed inspectors to come out and show me what they want befor I did a job I'd consider going back to school.
> 
> The inspector is 100 percent correct and you should be happy that you finally have an inspector with a hint of a clue after all these years. The fact that you have been doing it wrong all this time is not the inspectors problem.


go **** yourself asshole.


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## electricmanscott (Feb 11, 2010)

gmbjr said:


> go **** yourself asshole.


Typical. :laughing:


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## gmbjr (Mar 25, 2010)

electricmanscott said:


> What code do you work under?
> 
> If it's the NEC than this statement shows you are not getting what everyone is telling you.


i "get" it all. He is enacting a stronger standard. The code doesnt "require" the second rod except under certain circumstances. In one twp an inspector will TELL you to leave the ground rods 6" above grade so they can see the connection despite what the code says. Some require a #4 bare copper for all the grounding on a 200A service though that is not a requirement. The inspector is the boss. If you are not working in an area under the jurisdiction of an inspector with whom you've previously worked, it becomes impossible to know what to do to satisfy the guy without calling him and asking exactly what HE wants. I have been told, and I quote" I dont give a **** what the code book says, it's what I say". So dont be giving me **** for doing what needs to be done to satisfy the bevy of different ideas among the inspectors from one neighborhood to another.


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## electricmanscott (Feb 11, 2010)

gmbjr said:


> i "get" it all. He is enacting a stronger standard. The code doesnt "require" the second rod except under certain circumstances. In one twp an inspector will TELL you to leave the ground rods 6" above grade so they can see the connection despite what the code says. Some require a #4 bare copper for all the grounding on a 200A service though that is not a requirement. The inspector is the boss. If you are not working in an area under the jurisdiction of an inspector with whom you've previously worked, it becomes impossible to know what to do to satisfy the guy without calling him and asking exactly what HE wants. I have been told, and I quote" I dont give a **** what the code book says, it's what I say". So dont be giving me **** for doing what needs to be done to satisfy the bevy of different ideas among the inspectors from one neighborhood to another.



That's pathetic. Your inspectors really suck. On top of that, they are not too bright.

You are reading it backwards. The code absolutely does require a second rod. It allows you to NOT add the rod under certain circumstances.


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## gmbjr (Mar 25, 2010)

electricmanscott said:


> That's pathetic.


you're pathetic and a jackass.


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## electricmanscott (Feb 11, 2010)

gmbjr said:


> you're pathetic and a jackass.


Maybe so, but I know my code. Can you say the same? :no: :laughing:

Why are you stealing this work anyway. Isn't there a mall to be wired somewhere?


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## william1978 (Sep 21, 2008)

gmbjr said:


> now I find this....which is contradicting what i found on the Fluke website and the little note in the NEC...
> 
> http://www.illustratedhomeonline.com/details.php?gid=68&pid=2436












http://javascript<b></b>:history.go(-1)


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## NolaTigaBait (Oct 19, 2008)

gmbjr said:


> okay, so I'll buy the part where the inspector assumes the resistance isn't going to be low enough so he is enacting a stronger standard in his jurisdiction. No biggie.
> 
> Heres a new question though:
> 
> Some of you are saying simply drive the 2nd rod and connect the two in series. The code section has a little note mentioning paralleling. The Fluke website shows parallel. My personal opinion is it should either be paralleled or make a grid by connecting the 2 rods and running back to the panel.....can anyone show an illustration of which the code requires?:001_huh:


What do you mean by "paralelling"? Are you talking about the 2nd rod?


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## sparks134 (Jan 30, 2009)

william1978 said:


>


 Does the wire have to be bare solid too?


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## slickvic277 (Feb 5, 2009)

GMBJR, is correct. In the greater Philadelphia metro area a second ground rod has never been required. The grounding of residential services in this area has always been the cold water pipe, jumper from one side of the water meter to the other and a ground rod and the hot and cold water pipe at the water heater be bonded, That's it. Now I understand that 250.56 states that,

"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 250.52A(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. "

With that said I've never seen anyone take a resistance reading of a ground rod in a residential setting and the rod plus the water pipe has always been an acceptable grounding system.

If the inspector wants a second ground rod then first a measurement should be taken to see if the first rod meets the 25 ohm requirement.

IMO the inspector is a little over the top with the second ground rod requirement. I have never seen in this area more then one ground rod in a residential setting. ( as long as a water pipe is used as well ).


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## electricmanscott (Feb 11, 2010)

I just love the "it's the way we've always done it" argument.


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## NolaTigaBait (Oct 19, 2008)

electricmanscott said:


> I just love the "it's the way we've always done it" argument.


That argument is cool until you go out on your own and actually have to read the code book.


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## jwjrw (Jan 14, 2010)

william1978 said:


> Inspectors here will let you get by with one ground rod if you can show them that it is below 25 ohms. Everyone just puts two rods and be done with it.


 
I thought mecklenburg required 2 no matter what.


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## electricmanscott (Feb 11, 2010)

NolaTigaBait said:


> That argument is cool until you go out on your own and actually have to read the code book.


Or an inspector that has actually read one shows up!


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## NolaTigaBait (Oct 19, 2008)

electricmanscott said:


> Or an inspector that has actually read one shows up!


Yeah, not too many of those here. If I became an inspector, I would be murdered.


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## slickvic277 (Feb 5, 2009)

electricmanscott said:


> I just love the "it's the way we've always done it" argument.


The second is a supplement not a requirement. It's only needed if the first is over 25 ohms to ground, right?




NolaTigaBait said:


> That argument is cool until you go out on your own and actually have to read the code book.



It never get's old. Another contractor who thinks he's gods gift because "He's out on his own".

FWIW, I wouldn't argue with any inspector, they have the final say so I would just drive the second rod. But to act like it's a requirement is a bit self serving, trying to prove how smart you are, the second rod is not an automatic.You want the second rod, fine only if the first rod is over 25 ohms to ground.That's what the code says.

"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 250.52A(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. "


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## Dennis Alwon (May 9, 2009)

Slick-- the second rod is a requirement if the first rod is greater than 25 ohms. Why do you say the inspector is over the top to require this. You have an option to do a 3 point ground test on the rod and see if it has 25 ohms or less.

In most area you will not achieve this requirement so it is generally cheaper and easier to just add the second rod. Perhaps your area has incredible soil conditions and you can get 25 or less-- the inspector may know this so they don't require it.


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## Jim Port (Oct 1, 2007)

Raider,



slickvic277 said:


> "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 250.52A(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. "


Since you don't have a single electrode when you have both a water line and a ground rod I think the inspector requiring a second rod is exceeding the requirement. The above has always be interpreted in my area to mean if you only have one rod it needs to be <25 ohms or the second rod is needed, unless proved <25 ohms.

As far as being driven below dirt the inspector is 100% correct. The code calls for 8' in contact with the earth. Hard to do when 6" of an 8' rod is above the surface.


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## slickvic277 (Feb 5, 2009)

> Dennis Alwon;214054]Slick-- the second rod is a requirement if the first rod is greater than 25 ohms. Why do you say the inspector is over the top to require this. You have an option to do a 3 point ground test on the rod and see if it has 25 ohms or less.


I understand about the 25 ohms or less,I've posted the article twice in this thread already. perhaps "over the top" was the wrong wording.Here in the Philadelphia area there are 1000's of homes for block after block and never have I seen 2 rods here, not saying it's either right or wrong, just what the normal accepted practice is here. 



> In most area you will not achieve this requirement so it is generally cheaper and easier to just add the second rod. Perhaps your area has incredible soil conditions and you can get 25 or less-- the inspector may know this so they don't require it.


The only thing I can think of is there going to start insisting on 2 rods just like near buy South Jersey does, in any case I wouldn't argue with the inspector I would just do what he says, with a smile.

My point was the inspector was not on par with what the accepted practice is here, right or wrong, maybe a little explanation on the inspectors part would have caused the OP to have a different view on the situation.


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## slickvic277 (Feb 5, 2009)

Jim Port said:


> Raider,
> 
> 
> 
> ...


Agreed 1000% :thumbsup:


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## electricmanscott (Feb 11, 2010)

Jim Port said:


> Raider,
> 
> 
> 
> ...



You nailed some of the second part 250.53(G) for the 8' requirement but in addition to that later in that same article it requires the top of the rod to be driven flush with or below grade unless protected from physical damage.

But you bombed on the first.



_250.52 (D) (2) A metal underground water pipe shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) trough (A)(8). Where the supplemental electrode is a rod, pipe, or plate type it shall comply with 250.56

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 of any types specified by blah blah blah....
_
So the rod that supplements the water pipe has to comply with 250.56 which says that if it does not have a resistance of 25 ohms or less it shall be augmented by another electrode (another rod is fine). 

You guys can get as angry as you want. If you are bound to abide by the NEC you have been doing it wrong. The fact that the inspectors let it go is another issue. What's worse is the fact that they seem to have you guys by the nuts and nobody says boo about it. 

Here is the handbook commentary...


_Section 250.53(D)(2) specifically requires that rod pipe or plate electrodes used to supplement metal water piping be installed in accordance with 250.56. This requirement clarifies that the supplemental electrode system must be installed as if it were the sole grounding electrode for the whole system. If 25 ohms or less of earth resistance can not be achieved using one rod, pipe, or plate electrode, another electrode (other than the metal piping that is being supplemented) must be provided.
_


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## Protech (Aug 6, 2009)

Please forgive my ignorance, but what is the actual test method for determining the GE’s resistance? Do you disconnect 1 GE from the GEC and measure the resistance between the 2?


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## Jim Port (Oct 1, 2007)

electricmanscott said:


> You nailed some of the second part 250.53(G) for the 8' requirement but in addition to that later in that same article it requires the top of the rod to be driven flush with or below grade unless protected from physical damage.
> 
> But you bombed on the first.
> 
> ...


Scott, I am not getting angry in the least, but I don't see this as a *single* electrode. I do see the Handbook commentary that says bascially that the primary electrode gets ignored. We also know that the Handbook is the opinion of its author, not the actual code.


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## knomore (Mar 21, 2010)

Around here the inspector doesn't require 2 ground rods, but the utility does. They won't hook you up if you don't have 2...


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## ColoradoMaster3768 (Jan 16, 2010)

I'm surprised this issue hasn't come up before. Unless I'm seriously mistaken, the Code requirement for the driven ground rod to meet the 25 ohms or less criteria, or supplement it with a second ground rod, has been around at since 1975 -- 1978 to be sure.


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## RIVETER (Sep 26, 2009)

Ways of thinking have changed since people actually really started to admit that the water pipe ground is not as reliable as it once was. I am wondering if there is really any viable reason to include it as a grounding electrode at all, but that could be a different thread.


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## Old man (Mar 24, 2010)

You are right. It should have come up b4 or shortly after 1975 or 1980. However, during a serious drought here in the south with the lack of moisture it became an issue. So much so that everyone drives 2 rods now. 

I have asked some supply houses how many 8' ground rods they sell now. There reply, "Not near as many 6' ground rods".

Another point. 

An existing service has one driven ground. A detached building is added and fed from the existing service. Of couse the EC has to provide 2 driven grounds. In the last few years it has always been 2 grounds for the detached bldg. Well I am not sure where it is in the NEC but I think it states that the main service shall have the best ground. Or it states that no supply can have a better ground than that of the main. Any ways food for thought.


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## ColoradoMaster3768 (Jan 16, 2010)

Protech said:


> Please forgive my ignorance, but what is the actual test method for determining the GE’s resistance? Do you disconnect 1 GE from the GEC and measure the resistance between the 2?


 
Protech, everything I know is old, so please forgive me my ignorance of current technology. Normally, (as "normally" in yesteryear) you would perform a 3- or some cases a 4-point "Fall of Potential" test, which required special instruments and training. You will find a relatively decent explanation, with pictures, at this URL: http://www.kilowattclassroom.com/Archive/GndTestArticle.pdf 

As you know, grounding has always been critical for electrical systems, because as you also know, solid, low-resistance grounding helps stabilize the voltage reference point and really, really helps overcurrent protection schemes operate more effectively.


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## I_get_shocked (Apr 6, 2009)

sparks134 said:


> Only a few inches below grade? :001_huh:



yes. Enough so that it is protected. Code doesn't supply a min depth. You can even secure #6 along the house if you wanted.


If you dont want to drive ground rods theres always a ground ring lol.


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## RIVETER (Sep 26, 2009)

Old man said:


> You are right. It should have come up b4 or shortly after 1975 or 1980. However, during a serious drought here in the south with the lack of moisture it became an issue. So much so that everyone drives 2 rods now.
> 
> I have asked some supply houses how many 8' ground rods they sell now. There reply, "Not near as many 6' ground rods".
> 
> ...


At the attached building, where are you attaching the conductor from the driven ground?


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## Jim Port (Oct 1, 2007)

RIVETER said:


> At the attached building, where are you attaching the conductor from the driven ground?


This would originate at the grounding buss.


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## Jim Port (Oct 1, 2007)

ColoradoMaster3768 said:


> As you know, grounding has always been critical for electrical systems, because as you also know, solid, low-resistance grounding helps stabilize the voltage reference point and really, really helps overcurrent protection schemes operate more effectively.


Are you saying a ground rod is needed to clear a fault and to trip the breaker?


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## RIVETER (Sep 26, 2009)

Jim Port said:


> This would originate at the grounding buss.


I was just verifying that the panel would be a sub-panel...and neutral and ground not connected.


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## sparks134 (Jan 30, 2009)

I_get_shocked said:


> yes. Enough so that it is protected. Code doesn't supply a min depth. You can even secure #6 along the house if you wanted.
> 
> 
> If you dont want to drive ground rods theres always a ground ring lol.


 Does it have to be bare solid?


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## RIVETER (Sep 26, 2009)

Jim Port said:


> Are you saying a ground rod is needed to clear a fault and to trip the breaker?


To me he seems to be saying so, but I think that would be incorrect based on what we know as the purpose of a ground rod.


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## Jim Port (Oct 1, 2007)

RIVETER said:


> To me he seems to be saying so, but I think that would be incorrect based on what we know as the purpose of a ground rod.


 
I agree but was looking for confirmation.


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## RIVETER (Sep 26, 2009)

Jim Port said:


> I agree but was looking for confirmation.


I think he has good info, though. A lot of times I write faster than my brain spells. Or something like that.


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## ColoradoMaster3768 (Jan 16, 2010)

Jim Port said:


> Are you saying a ground rod is needed to clear a fault and to trip the breaker?


 
No, what I am saying is the breaker or fuse operates in proportion the amount of heat flowing through. And, anytime you have a fault, beit line or ground fault, the voltage begins approaching zero. Therefore, the more solidly grounded your system,_ i.e., the closer you get it to zero,_ the quicker it will work for ground fault situations. 

Also, just as a less than solidly grounded Wye system will demonstrate unbalanced voltages, wherein the imbalance is driven by loading, a less than solidly grounded neutral in a secondary service will demonstrate the "floating neutral" situation that many of you have had experience with. 

Sorry is ramble, it is past my bedtime.


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## william1978 (Sep 21, 2008)

jwjrw said:


> I thought mecklenburg required 2 no matter what.


 No. Just prove that it doesn't need 2.


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## william1978 (Sep 21, 2008)

sparks134 said:


> Does the wire have to be bare solid too?


 No......


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## electricmanscott (Feb 11, 2010)

Jim Port said:


> Scott, I am not getting angry in the least, but I don't see this as a *single* electrode. I do see the Handbook commentary that says bascially that the primary electrode gets ignored. We also know that the Handbook is the opinion of its author, not the actual code.


Jim I have said all I can about this but you are wrong. You highlighted words and ignored other words. Key words that are important. I don't have the desire to argue this one any more. But I'll give it a final shot


_250.52 (D) (2) A metal underground water pipe shall be supplemented by an additional electrode of a type specified in 250.52(A)(2) trough (A)(8). Where the supplemental electrode is a rod, pipe, or plate type it shall comply with 250.56

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 of any types specified by 250.52(A)(4) trough (A)(8) _

So again, if the supplemental is a rod, IT SHALL COMPLY with 250.56 which means it must have a resistance of 25 ohms or less. If it does not it shall be augmented by another electrode. The electrodes that you can augment it with DO NOT include the metal underground water pipe and in fact this is specifically prohibited from being used to augment the supplemental electrode as it is not listed in 250.52(A)(4) trough (A)(8) which is what you must use to augment the suplemental electrode..



The whole point of the supplemental electrode is in the event the water line electrode is lost (replaced with plastic) you have a code compliant electrode. A single rod in most cases will not meet the requirements.

BTW, I didn't mean you were getting angry, I was talking about the two Philly yahoos. :laughing:


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## I_get_shocked (Apr 6, 2009)

sparks134 said:


> Does it have to be bare solid?


I *think* it may be insulated, bare, solid, or stranded.

I looked though Article 250 and I don't believe its specified.


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## Electric Al (Mar 13, 2010)

We usually use a ground plate,buried a minimum of 2 feet in undisturbed ground,with a # 6 copper conductor to the neutral/ground buss bar.


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## Dennis Alwon (May 9, 2009)

Electric Al said:


> We usually use a ground plate,buried a minimum of 2 feet in undisturbed ground,with a # 6 copper conductor to the neutral/ground buss bar.


Article 250.53(H) requires a minimum of 30" below the surface of the earth for a plate electrode.


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## Electric Al (Mar 13, 2010)

I stand corrected.


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## Protech (Aug 6, 2009)

Man, that's neat trick. How do you bury something without disturbing the ground?:jester:



Electric Al said:


> We usually use a ground plate,buried a minimum of 2 feet in undisturbed ground,with a # 6 copper conductor to the neutral/ground buss bar.


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## Electric Al (Mar 13, 2010)

HA - HA - HA ! ! !:laughing::laughing::laughing:


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## varmit (Apr 19, 2009)

Residential grounding is probably the facet of electrical work with the most varied requirements from one jurisdiction to another. 

Here are some requirements that I have seen or heard of in different locations:

Must NOT bond service to water line.
Must bond to water line 2 feet outside of house, even if plastic pipe. (Yes, I know this is dumb.)
GEC must be a continuous conductor, from meter base to ground rod to water pipe inside of building.
Metal duct work to be bonded.
GEC must be ran to weatherhead to attach to utility service drop.
Ufer required instead of ground rod.
Ufer required in addition to ground rod and water pipe ground.
Ufer only allowable ground.
No GEC required. ( This area had no inspection. They now have inspections here.)
One driven ground rod is only electrode required.
I am sure that this is only a partial list.


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## crosport (Apr 4, 2010)

Hook-up one lead of a pigtail socket to a 15amp breaker in the panel and connect the other lead to the isolated main ground conductor.Screw 15amp plug fuse into socket and turn breaker on.If fuse blows you know the resistance is adequate.Ohms law R=E/I R=120/15=8 ohms which is below the max of 25 ohms.We use a ground plate in B.C. as opposed to rods.Just need to dig a 2' deep hole and throw it in.We find it easier than driving 2 10' rods.


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## Electric Al (Mar 13, 2010)

I remember driving a ground rod (at that time there were no ground plates)........ to continue the story.... at a cottage. I was pounding it in with a sledge hammer, and it took me a long time . Finally it was in,I looked under the crawl space and the pointed end was back up about 2 feet. It must have hit a flat rock, and just followed the shape of the rock.. Needless to say it stayed like that !!! :yes::yes::yes::yes:


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## ColoradoMaster3768 (Jan 16, 2010)

Apparently, you did some "pounding." :thumbsup:


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## Old man (Mar 24, 2010)

crosport said:


> Hook-up one lead of a pigtail socket to a 15amp breaker in the panel and connect the other lead to the isolated main ground conductor.Screw 15amp plug fuse into socket and turn breaker on.If fuse blows you know the resistance is adequate.Ohms law R=E/I R=120/15=8 ohms which is below the max of 25 ohms.We use a ground plate in B.C. as opposed to rods.Just need to dig a 2' deep hole and throw it in.We find it easier than driving 2 10' rods.


 How is digging a 2x2x2 ft hole easier than driving 2 8 ft gd rods? using a hammer drill for driving the gd rods. No way.


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## crosport (Apr 4, 2010)

In this part of the country you'll usually encounter bedrock at about 3'.A lot of the houses don't have basements.We were able to install 2 6' rods at one time but the code changed requiring 2 10' rods.You can still use rods but we just go with the plate instead.Or in the case of new residential we try and put a ufer grnd. in the footing as long as the footing is at least 2' deep.


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