# Ground rod / water pipe scheme



## swimmer (Mar 19, 2011)

I want to run only 1 GEC into the service panel. I'm installing 2 ground rods and I'm bonding to the water pipe. Is this scheme allowed by code?
Please see attachment.
Thanks


----------



## dronai (Apr 11, 2011)

Why two gr's ?

I've had inspectors want one continuous bare cu wire unbroken

I usually run one from the CW direct, and gas bond at the WH

One from the GR direct to the GB


----------



## HARRY304E (Sep 15, 2010)

swimmer said:


> I want to run only 1 GEC into the service panel. I'm installing 2 ground rods and I'm bonding to the water pipe. Is this scheme allowed by code?
> Please see attachment.
> Thanks


Yes.



> *250.104 Bonding of Piping Systems and Exposed Structural
> Steel.*
> (A) Metal Water Piping. The metal water piping system
> shall be bonded as required in (A)(1), (A)(2), or (A)(3) of
> ...


----------



## HARRY304E (Sep 15, 2010)

dronai said:


> Why two gr's ?
> 
> I've had inspectors want one continuous bare cu wire unbroken
> 
> ...


..........



> 250.53 Grounding Electrode System Installation.
> Informational Note: See 547.9 and 547.10 for special
> grounding and bonding requirements for agricultural
> buildings.
> ...


----------



## raider1 (Jan 22, 2007)

Your posted schematic is Ok but remember that the GEC to the ground rods must be full sized based on 250.66 because it is not the sole connection to the ground rod.

Chris


----------



## dronai (Apr 11, 2011)

HARRY304E said:


> ..........


 
Why two GR's ? One with 25 ohms or less. I've never had to install two.


----------



## McClary’s Electrical (Feb 21, 2009)

dronai said:


> Why two GR's ? One with 25 ohms or less. I've never had to install two.


How do you prove that?


----------



## dronai (Apr 11, 2011)

HARRY304E said:


> ..........





mcclary's electrical said:


> How do you prove that?


Didn't you see my post on measuring ground rod resistance ?

You prove it by passing inspection. Like I said, (in Calif.) I have never had to install two.


----------



## HARRY304E (Sep 15, 2010)

dronai said:


> Why two GR's ? One with 25 ohms or less. I've never had to install two.


Any of the Electrical inspectors Around here will make you prove it so we install 2 Ground Rods 6' apart every time.


----------



## Dennis Alwon (May 9, 2009)

Most areas of the country you will never achieve 25 ohms with 2 rods nevermind one rod. Thus we just install 2 rods.


----------



## DiegoXJ (Jul 29, 2010)

dronai said:


> Didn't you see my post on measuring ground rod resistance ?
> 
> You prove it by passing inspection. Like I said, (in Calif.) I have never had to install two.



I'm in Ca. Have had to install (2) for inspection in SF. I'm, sure we could have gotten testing done, but it's just easier to install a second rod.


----------



## McClary’s Electrical (Feb 21, 2009)

DiegoXJ said:


> I'm in Ca. Have had to install (2) for inspection in SF. I'm, sure we could have gotten testing done, but it's just easier to install a second rod.


Around here, one rod gets you about 95 ohms, I guarantee two doesn't even bring it under 25


----------



## dronai (Apr 11, 2011)

DiegoXJ said:


> I'm in Ca. Have had to install (2) for inspection in SF. I'm, sure we could have gotten testing done, but it's just easier to install a second rod.


 
Was that Residential, or commercial ?


----------



## swimmer (Mar 19, 2011)

*or to the one or more grounding electrodes used.
*Thanks Harry. That language certainly makes it clear that the wire from the water pipe can be attached to one of the ground rods rather than being run directly into the panel.


----------



## dronai (Apr 11, 2011)

Dennis Alwon said:


> Most areas of the country you will never achieve 25 ohms with 2 rods nevermind one rod. Thus we just install 2 rods.


 
If it's new construction, you just use one Ufer only right ? Your specifically talking about old work upgrade, or improvements ?


----------



## nhanson (Apr 17, 2010)

We also install 2. no need to worry about testing then.


----------



## DiegoXJ (Jul 29, 2010)

dronai said:


> Was that Residential, or commercial ?



Residential

Although I will admit that outside of SF the inspectors will let just driving 1 rod and connecting to the water main go.


----------



## McClary’s Electrical (Feb 21, 2009)

dronai said:


> If it's new construction, you just use one Ufer only right ? Your specifically talking about old work upgrade, or improvements ?


What does it matter. He's stating one rod in most cases does not get you below 25 ohms.


----------



## swimmer (Mar 19, 2011)

dronai said:


> Why two gr's ?
> 
> I've had inspectors want one continuous bare cu wire unbroken
> 
> ...





dronai said:


> Why two GR's ? One with 25 ohms or less. I've never had to install two.


For a single ground rod installation in Ventura County CA, the inspector sometimes requires a resistance measurement between the rod and ??? (I forgot but I think it is a stake or probe in the dirt). The electrician is responsible for providing this measurement. It requires a megger and I don't have one. I don't want to buy or rent one either. I understand that they cost thousands of $.

If you install 2 ground rods, then no measurement is required.


----------



## McClary’s Electrical (Feb 21, 2009)

swimmer said:


> For a single ground rod installation in Ventura County CA, the inspector sometimes requires a resistance measurement between the rod and ??? (I forgot but I think it is a stake or probe in the dirt). The electrician is responsible for providing this measurement. It requires a megger and I don't have one. I don't want to buy or rent one either. I understand that they cost thousands of $.
> 
> If you install 2 ground rods, then no measurement is required.


You caannot perform that test with a megger


----------



## swimmer (Mar 19, 2011)

dronai said:


> If it's new construction, you just use one Ufer only right ? Your specifically talking about old work upgrade, or improvements ?


My specialty is old work upgrades. Mostly troubleshooting and correcting hack wiring for realtors. Many foreclosed houses in bad condition. I don't often install service panels. I did a 200A upgrade where the inspector told me he'd allow the old 1.25" mast and he provided the megger and performed the measurement for a single ground rod installation. 

But I don't want to assume inspectors will cut me so much slack.


----------



## McClary’s Electrical (Feb 21, 2009)

swimmer said:


> My specialty is old work upgrades. Mostly troubleshooting and correcting hack wiring for realtors. Many foreclosed houses in bad condition. I don't often install service panels. I did a 200A upgrade where the inspector told me he'd allow the old 1.25" mast and he provided the megger and performed the measurement for a single ground rod installation.
> 
> But I don't want to assume inspectors will cut me so much slack.


You can't perform that test with a megger


----------



## Dennis Alwon (May 9, 2009)

dronai said:


> If it's new construction, you just use one Ufer only right ? Your specifically talking about old work upgrade, or improvements ?


That is correct. If you have a ufer then you do not need ground rods.


----------



## dronai (Apr 11, 2011)

mcclary's electrical said:


> What does it matter. He's stating one rod in most cases does not get you below 25 ohms.


Chill ! I'm here to learn too. This is the first place, I have ever heard of needing two. I've worked one Service upgrade in San Mateo, near San Francisco, and only one also.


----------



## dronai (Apr 11, 2011)

Dennis Alwon said:


> That is correct. If you have a ufer then you do not need ground rods.


I meant you don't need two Ufers. I guess much less resistance with a 20' piece of steel embedded in the concrete.


----------



## swimmer (Mar 19, 2011)

dronai said:


> If it's new construction, you just use one Ufer only right ? Your specifically talking about old work upgrade, or improvements ?





mcclary's electrical said:


> You caannot perform that test with a megger


Yes, I know... One of these days I'll get these expensive instruments sorted out. The last time I tried to understand, it went something like this: A company called Megger makes an instrument for the ground rod measurement but the instrument is not called a Megger.


----------



## dronai (Apr 11, 2011)

Ground Rods, and Ground Fault Trip requirement- 25 Ohms or less

120V/25R = 4.8 A not enough to trip a 15A CB

Why do they use that resistance, when it doesn't look like it's low enough ? I would think you need 5 ohms or less


----------



## Dennis Alwon (May 9, 2009)

dronai said:


> Ground Rods, and Ground Fault Trip requirement- 25 Ohms or less
> 
> 120V/25R = 4.8 A not enough to trip a 15A CB
> 
> Why do they use that resistance, when it doesn't look like it's low enough ?


No one seems to know where the 25 ohms comes from but a ufer or ground rod is not there to trip a breaker. It is mostly for surges and lightning.


----------



## Dennis Alwon (May 9, 2009)

dronai said:


> I meant you don't need two Ufers. I guess much less resistance with a 20' piece of steel embedded in the concrete.


 Usually all the steel in the footer is tied together so 2 ufers doesn't make sense.


----------



## dronai (Apr 11, 2011)

Dennis Alwon said:


> Usually all the steel in the footer is tied together so 2 ufers doesn't make sense.


 
Herbert G Ufer


----------



## dronai (Apr 11, 2011)

Dennis Alwon said:


> No one seems to know where the 25 ohms comes from but a ufer or ground rod is not there to trip a breaker. It is mostly for surges and lightning.


Found this one By Don Resqcapt19


You're missing the point. The current only wants to return to its source. While the grounding electrode does provide an indirect path back to the source, that is not the code indented fault clearing path. The path back to the source via the grounding electrode system should be a much higher impedance path than that via the equipment grounding conductor and the main bonding jumper. In fact the code required fault clearing path in a properly installed system will be hundreds of times better than the path via the grounding electrode system.
A 5 ohm grounding electrode system (if that is the only fault clearing path) might never clear a fault even on a 20 amp breaker and would place a lethal voltage on everything connected to the electrical system. The trip time for one name brand 20 amp breaker is between 45 seconds and never. The hazard exists until the fault is cleared.
Don


----------



## erics37 (May 7, 2009)

swimmer said:


> I want to run only 1 GEC into the service panel. I'm installing 2 ground rods and I'm bonding to the water pipe. Is this scheme allowed by code?
> Please see attachment.
> Thanks


If you hit the water pipe first with the full size GEC then you can hit the ground rods with smaller jumpers and maybe save a buck.


----------



## RIVETER (Sep 26, 2009)

swimmer said:


> I want to run only 1 GEC into the service panel. I'm installing 2 ground rods and I'm bonding to the water pipe. Is this scheme allowed by code?
> Please see attachment.
> Thanks


To me the illustration is deceptive. I would want the grounding electrodes to be in parallel...not in series.


----------



## swimmer (Mar 19, 2011)

RIVETER said:


> To me the illustration is deceptive. I would want the grounding electrodes to be in parallel...not in series.



If by parallel, you mean that wire from both ground rods should run into the panel then that defeats my intent. I'm trying to run only one GEC into the panel.


----------



## HARRY304E (Sep 15, 2010)

swimmer said:


> If by parallel, you mean that wire from both ground rods should run into the panel then that defeats my intent. I'm trying to run only one GEC into the panel.



You can do it with one wire hit the ground rod that is the furthest away sleeve the wire through the second ground rod acorn then hit the meter socket to the panel to the water meter.:thumbsup:


----------



## Wireman191 (Aug 28, 2011)

RIVETER said:


> To me the illustration is deceptive. I would want the grounding electrodes to be in parallel...not in series.


 I'm just trying to figure out in my head how this could be accomplished.


----------



## HARRY304E (Sep 15, 2010)

Wireman191 said:


> I'm just trying to figure out in my head how this could be accomplished.


I think he is talking about running 2 separate wires from each ground rod which is not required by the code.


----------



## Black Dog (Oct 16, 2011)

swimmer said:


> If by parallel, you mean that wire from both ground rods should run into the panel then that defeats my intent. I'm trying to run only one GEC into the panel.


You only need one wire that is sized properly.:thumbsup:


----------



## raider1 (Jan 22, 2007)

RIVETER said:


> To me the illustration is deceptive. I would want the grounding electrodes to be in parallel...not in series.


And what would the benefits of running parallel GEC's to the electrodes be?

Chris


----------



## Briancraig81 (May 25, 2007)

Around here in the Raleigh area, they didn't start requiring us to drive two ground rods until 2005. You can still drive one but you have to prove that it's under 25 ohms. I never have asked an inspector but I've wondered if they started making us drive two since most plumbing installations are now almost always in plastic (PEX). It kinda makes sense because you don't have the cold water ground.


----------



## RePhase277 (Feb 5, 2008)

The 25 ohm requirement is very old, as well as the requirement to supplement the electrode if it can't be achieved with one. My 1914 Hawkins Electrical Guides mention it.
So, in reality, it should never have been legal to use just one rod without testing. It was just overlooked for many years in many places.

We started getting called on it in the North Georgia area in '03 or '04.


----------



## Big John (May 23, 2010)

dronai said:


> Herbert G Ufer


 I used to think it was "UFer" for "Under Footing" ground. Come to find out it was some poor guy's name.

-John


----------



## brian john (Mar 11, 2007)

InPhase277 said:


> The 25 ohm requirement is very old, as well as the requirement to supplement the electrode if it can't be achieved with one. My 1914 Hawkins Electrical Guides mention it.
> So, in reality, it should never have been legal to use just one rod without testing. It was just overlooked for many years in many places.
> 
> We started getting called on it in the North Georgia area in '03 or '04.


As someone that makes a living testing, I have to ask *WHY*.

If one rod gives you 200 ohms and a second rod gives you 199 ohms, what have you gained.

If 25 ohms is a magic number then EVERY electrode system should have to meet that standard?

Now if you want to say two rods is the standard, no matter what the tested values, I'll buy that.


----------



## brian john (Mar 11, 2007)

raider1 said:


> And what would the benefits of running parallel GEC's to the electrodes be?
> 
> Chris


 
The thought is (by some) that it gives the lightning strike multiple current paths from the panel out to Earth.


----------



## RePhase277 (Feb 5, 2008)

brian john said:


> As someone that makes a living testing, I have to ask *WHY*.
> 
> If one rod gives you 200 ohms and a second rod gives you 199 ohms, what have you gained.
> 
> ...


Two rods just take advantage of what I think is a verbal loophole in the code language. The verbiage hasn't changed. I also think that the 25 ohm number was pulled out of the air by some of the early grounding pioneers.

I don't think a 50,000 amp lightning strikes gives a rat's arse if it's 5, 25, or 2500 ohms.


----------



## RIVETER (Sep 26, 2009)

raider1 said:


> And what would the benefits of running parallel GEC's to the electrodes be?
> 
> Chris


Multiple paths for the strike. Let's face it, lightning always finds a way to go without a building there. Not knowing where a strike will occur and why it takes certain paths creates all kinds of explanations as to how to mitigate. If the code gives a minimum requirement, why not do just a little extra?


----------



## raider1 (Jan 22, 2007)

RIVETER said:


> Multiple paths for the strike. Let's face it, lightning always finds a way to go without a building there. Not knowing where a strike will occur and why it takes certain paths creates all kinds of explanations as to how to mitigate. If the code gives a minimum requirement, why not do just a little extra?


The purpose of the grounding electrode system required by the NEC is not to protect the building and the electrical system from a direct lightning strike but to dissipate lightning induced currents that occur within a buildings electrical system from storms.

If you want to provide multiple paths to earth to direct a lightning strike around the building then you must install a lightning protection system in accordance with NFPA 780.

As far as "Giving a little extra" running a separate #6 to 2 ground rods will not appreciably decrease the resistance of the grounding electrode system in the event of a direct lightning strike so it is a waste of time and material IMHO.

Chris


----------



## swimmer (Mar 19, 2011)

Any maximum length for GEC that runs from rod to panel? I've got concrete under the panel and dirt about 8 feet away.


----------



## RePhase277 (Feb 5, 2008)

swimmer said:


> Any maximum length for GEC that runs from rod to panel? I've got concrete under the panel and dirt about 8 feet away.


Of course, as short as possible is always best, but there is no maximum. I have had to run GEC's more than 100 feet long.


----------



## dronai (Apr 11, 2011)

swimmer said:


> Any maximum length for GEC that runs from rod to panel? I've got concrete under the panel and dirt about 8 feet away.


 
Why don't you just drill the concrete, it's probably only two inches thick


----------



## swimmer (Mar 19, 2011)

raider1 said:


> Your posted schematic is Ok but remember that the GEC to the ground rods must be full sized based on 250.66 because it is not the sole connection to the ground rod.
> 
> Chris


According to 250.66(A), it looks like I can use 6AWG solid to connect from the water pipe to the panel ground bus if I choose to abandon my 1 wire into the panel scheme. Looks like I just have to inclose in EMT where it runs along exterior walls of the house.


----------



## HARRY304E (Sep 15, 2010)

swimmer said:


> According to 250.66(A), it looks like I can use 6AWG solid to connect from the water pipe to the panel ground bus if I choose to abandon my 1 wire into the panel scheme. Looks like I just have to inclose in EMT where it runs along exterior walls of the house.


You can also use PVC for that.


----------



## McClary’s Electrical (Feb 21, 2009)

swimmer said:


> According to 250.66(A), it looks like I can use 6AWG solid to connect from the water pipe to the panel ground bus if I choose to abandon my 1 wire into the panel scheme. Looks like I just have to inclose in EMT where it runs along exterior walls of the house.


The emt requires bonding both ends to avoid a choke effect. Just use pvc


----------



## EC2253 (Mar 7, 2008)

swimmer said:


> My specialty is old work upgrades. Mostly troubleshooting and correcting hack wiring for realtors. Many foreclosed houses in bad condition. I don't often install service panels. I did a 200A upgrade where the inspector told me he'd allow the old 1.25" mast and he provided the megger and performed the measurement for a single ground rod installation.
> 
> How did you manage that?


----------



## swimmer (Mar 19, 2011)

EC2253 said:


> swimmer said:
> 
> 
> > My specialty is old work upgrades. Mostly troubleshooting and correcting hack wiring for realtors. Many foreclosed houses in bad condition. I don't often install service panels. I did a 200A upgrade where the inspector told me he'd allow the old 1.25" mast and he provided the megger and performed the measurement for a single ground rod installation.
> ...


----------



## dana1028 (Jul 15, 2011)

DiegoXJ said:


> I'm in Ca. Have had to install (2) for inspection in SF. I'm, sure we could have gotten testing done, but it's just easier to install a second rod.


SFO is not part of CA.

The Daly City Bldg. Dept. [borders San Fran] used to have a sign at the permit counter that read..."You are no longer in San Fran...so leave your "in San Fran we had to...comments in San Fran."


----------



## dana1028 (Jul 15, 2011)

dronai said:


> Chill ! I'm here to learn too. This is the first place, I have ever heard of needing two. I've worked one Service upgrade in San Mateo, near San Francisco, and only one also.


Most municipalities on the San Fran peninsula only require 1 rod....it's a regional thing...lots of conductive soil [wet clay, high water table, etc.].


----------

