Area controversy around sizing of GEC for ground rod

[Smart $]

I agree that the citation of 250.66(A) was improperly used in the Mike Holt slide for the 2005 code. In actuality, the proper citation would have been 250.53(E) when discussing the proper size bonding jumper between rods. (Same for 2008)

Using 'others' logic 250.53(E) does not apply. Note the word "sole".

Edit. Also it is not a supplemental electrode.

250.53(E) only applies to rpp-type supplemental electrodes. Supplemental electrodes only exist if there is a water pipe electrode - ref: 250.53(D)(2). If the supplemental electrode conductors are connected per the last part of 250.53(D)(2), the conductor would be a GEC and not a bonding jumper. 250.53(E) applies to rpp-type supplemental electrode that are bonded to the water pipe electrode... and the connecting conductor would be a bonding jumper.

The rods in the illustration could be supplemental electrodes, but they are not bonded to a water pipe electrode, so the conductor from the meter enclosure to the first rod is a GEC.

If the first rod was connected directly to a water pipe electrode, it would not be the sole connection to the rod electrode, so must be sized per table. The connecting conductor between rods would still be a bonding jumper, but it is also not connected to a metal water pipe electrode, so it too must be sized per table.

Again, I emphasize the above are literal interpretations only.

 

[Smart $]

The illustration is correct for the 2008.

Where is "electrode bonding jumper"?

Explain to me how Exhibit 250.31 works since the waterline has no 'sole connection'?

I wish they had used 350 for the service conductors.

As I said, by literal interpretation it is not.

The or an "electrode bonding jumper" is the conductor between and connecting two electrodes.

I don't have the handbook, so I cannot comment on Exhibit 250.31.

 

[Smart $]

View attachment 5292When using bonding jumpers between various electrodes the use of the word "sole" connection is pretty well visually explained in this slide. I could extend a #6 cu bonding jumper from ground rod #5 to another ground rod say, #7.

First off, the illustration does not give sizes.

Second, the rod shown is not a supplemental electrode. 250.53(D)(2) only requires one supplemental electrode. The first electrode connected by the water pipe electrode bonding jumper is the CEE, which satisfies the requirement. The bonding jumper is not connected to an rpp-type electrode, so 250.53(E) does not apply. Table sizing is required for all depicted bonding jumpers.

Additionally, I would debate #2 as qualifying as a frame electrode without connection to #5 rod, so #2 and #5 constitute only one electrode. Or we can consider #2 and #3 as one electrode. Either way, the conductor to the rod is a bonding jumper, so table sizing would be required (literal interpretation).

 

[wbalsam1]

250.53(E) only applies to rpp-type supplemental electrodes. Supplemental electrodes only exist if there is a water pipe electrode - ref: 250.53(D)(2). If the supplemental electrode conductors are connected per the last part of 250.53(D)(2), the conductor would be a GEC and not a bonding jumper. 250.53(E) applies to rpp-type supplemental electrode that are bonded to the water pipe electrode... and the connecting conductor would be a bonding jumper.

The rods in the illustration could be supplemental electrodes, but they are not bonded to a water pipe electrode, so the conductor from the meter enclosure to the first rod is a GEC.

If the first rod was connected directly to a water pipe electrode, it would not be the sole connection to the rod electrode, so must be sized per table. The connecting conductor between rods would still be a bonding jumper, but it is also not connected to a metal water pipe electrode, so it too must be sized per table.

Again, I emphasize the above are literal interpretations only.

Thanks for taking the time to spell it out. I think I've finally learned something! (and at my age....)

 

[LarryFine]

Aren't two or more made electrodes that are effectively bonded together considered a single electrode?

 

[Smart $]

Aren't two or more made electrodes that are effectively bonded together considered a single electrode?

Got a section reference?

What qualifies as a made electrode? Aren't all electrodes [man-] made? If one says it's an electrode which didn't exist previously, when does it cease to be a made electrode once it does exist?

Only such instance(s) I'm aware of is 250.52(A)(2) Metal Frame of the Building or Structure electrode, which under methods (2) and (3) therein requires connection to an earthed electrode. So while this could be considered two electrodes, it is still only one because without the earthed electrode, the frame is not.

Other than that some may construe the last sentence of 250.53, which says...

Two or more grounding electrodes that are bonded
together shall be considered a single grounding electrode
system.

 

[jxofaltrds]

Aren't two or more made electrodes that are effectively bonded together considered a single electrode?

Duplicate. Did not read enought.

 

[jxofaltrds]

250.66(a)(b)(c)

250.66(a)(b)(c)

Is talking about the GEC. Correct?

What is a GEC? That conductor between the service and the grounding electrode. Correct?

If I have only one GEC in my installation it is the "sole connection". Correct?

Note: it says connected "to" not connected "at".

So I can size it per 250.66. Correct?

Other conductors connected to the grounding electrode and not connected to the service are "bonding conductors". Correct?

If the above are true why would adding 1 or 200 bonding jumpers effect the GEC?

 

[radiopet]

IF we are dealing with the connection to a sole electrode which happens to be a rod then 6 AWG is all that is required. The fact you can't meet the requirements of the 25 ohms or less and an additional electrode is added makes no difference since connecting these two electrodes together creates a single electrode in my view. Also I hardly think lighting could care less. I have no worries if someone runs a 6 AWG to one rod and then loops to an additional rod...why would anyone be concerned over something that happens every day of the week.

 

[Dennis Alwon]

IF we are dealing with the connection to a sole electrode which happens to be a rod then 6 AWG is all that is required. The fact you can't meet the requirements of the 25 ohms or less and an additional electrode is added makes no difference since connecting these two electrodes together creates a single electrode in my view. Also I hardly think lighting could care less. I have no worries if someone runs a 6 AWG to one rod and then loops to an additional rod...why would anyone be concerned over something that happens every day of the week.

Paul I think most of us agree that a number 6 is all that is required when a continuous run to both rods is used. The question is the wording in the code book. Based on Rogers post from the CMP I believe we all see the intent but what do the words state. I still read it comfortably as only requiring a #6 but maybe that's what I want to read. I made a proposal to add an (s) after electrode in 250.66(A)- we'll see.

 

[Smart $]

IF we are dealing with the connection to a sole electrode which happens to be a rod then 6 AWG is all that is required. The fact you can't meet the requirements of the 25 ohms or less and an additional electrode is added makes no difference since connecting these two electrodes together creates a single electrode in my view.

I have no objections to your view... but back it up with a Code reference if you can!!!

 

[iwire]

IF we are dealing with the connection to a sole electrode which happens to be a rod then 6 AWG is all that is required. The fact you can't meet the requirements of the 25 ohms or less and an additional electrode is added makes no difference since connecting these two electrodes together creates a single electrode in my view.

250.56 clearly shows that is not true.

 

[Smart $]

Is talking about the GEC. Correct?

What is a GEC? That conductor between the service and the grounding electrode. Correct?

Yes, and yes with the exception the statement should be: The (or A) conductor between the service ground and one or more grounding electrodes. There can also be more than one GEC connecting one or more other grounding electrodes.

If I have only one GEC in my installation it is the "sole connection". Correct?

Note: it says connected "to" not connected "at".

Not necessarily (and not exactly). Sole connection as used in Article 250 is regarding a GEC connection "to" an electrode.

So I can size it per 250.66. Correct?

You have to. As for sizing it per one of the subsections thereto (i.e. smaller than Table 250.66), it must meet the condition specified therein.

Other conductors connected to the grounding electrode and not connected to the service are "bonding conductors". Correct?

Essentially yes... but they are connected to the service through the electrode, i.e. not directly through a GEC.

If the above are true why would adding 1 or 200 bonding jumpers effect the GEC?

Because the GEC connection to the electrode having bonding jumpers is not the sole connection, thus not meeting the conditions under 250.66 subsections.

****************************************************************

Anyway, I think we (or I) got off track when the MH illustration got posted. The OP (IIRC) was about "looping" through the first rod's acorn connector and on to the second. I have modofied the MH illustration to depict the two different scenarios. What say ye all to the interpretation depicted in the lower image...???

250.64(F) in the image refers specifically to the following part:

The grounding electrode conductor shall be sized for
the largest grounding electrode conductor required among
all the electrodes connected to it.

 

[wbalsam1]

IF we are dealing with the connection to a sole electrode which happens to be a rod then 6 AWG is all that is required. The fact you can't meet the requirements of the 25 ohms or less and an additional electrode is added makes no difference since connecting these two electrodes together creates a single electrode in my view. Also I hardly think lighting could care less. I have no worries if someone runs a 6 AWG to one rod and then loops to an additional rod...why would anyone be concerned over something that happens every day of the week.

'Single grounding electrode system in this sense" (250.58)

 

[jxofaltrds]

I GET IT NOW.

THANK YOU, THANK YOU, THANK YOU for taking the time to debate this with me.

(A,B,C) are restrictions. Note 2.b in table 250.66 helped me see this.

The rod(s) are not required to be larger than #6 because of 250.53(B).

So the wording in 250.66 does not have to be changed.

 

[roger]

Aren't two or more made electrodes that are effectively bonded together considered a single electrode?

IMO they are and the late George Flach also agreed.

From this site

Grounding-electrode continuity
Q: Does the grounding-electrode conductor to driven ground rods have to be unbroken to both rods or may a splice be made at the first rod, then continue to the second ground rod by installing two ground clamps at the first ground rod, then continuing to the second rod with a 6 AWG copper grounding-electrode conductor?

A: Where required to install two ground rods because a single rod has a resistance to earth of more than 25 ohms, and there are no other grounding electrodes at the site, the grounding-electrode conductor must be in an unbroken length from the service to the two ground rods. If spliced, an irreversible compression-type connector listed as grounding and bonding equipment or exothermic welding must be used to make the grounding-electrode conductor continuous.

Where it takes two ground rods to make a single grounding electrode because the resistance-to-earth of a single rod is more than 25 ohms, two driven rods are required to make one Code-recognized grounding electrode.

Where a single driven ground rod has a resistance-to-earth of 25 ohms or less, the grounding-electrode conductor is permitted to be run to any convenient electrode that is a part of the grounding-electrode system. This also applies to two or more ground rods. References for these requirements are in 250.50, 250.64(C) and 250.64(F).

Roger

 

[iwire]

IMO they are and the late George Flach also agreed.

IMO 250.56 does not agree.

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

So right there they IMO have told us a single electrode with a high resistance is still an electrode.

Further more if joining two ground rods together makes them 'one electrode' and that 'one electrode' had more than 25 ohms to ground we would have to add to it again.

We can't call two electrodes 'one' when it's convenient and call them 'two' when that is convenient.

 

[Smart $]

IMO they are and the late George Flach also agreed.

From this site

I would contend they do/are not... at least not by literal interpretation. There is no statement in Article 250 which specifically says so. No matter how many electrodes you install, or for what reason, each is an electrode and two or more comprise a system.

Where a water pipe electrode is present, a supplemental electrode is required. If that supplemental electrode was the first driven rod, which is augmented with the second rod, then by the reasoning you and others are using to call the two rods one Code-recognized electrode, all three "electrodes" would have to be considered one Code-recognized grounding electrode. I think not.

 

[roger]

By giving a single rod a value that must be met, the NEC has in effect stated that it is not an electrode and the wording of 250.56 is incorrect if the value is not met. That being the case, there is no electrode until the second rod is added, at the time this second rod is added and jumpered to the first we have an electrode.

Roger

 

[iwire]

By giving a single rod a value that must be met, the NEC has in effect stated that it is not an electrode

I see nothing in the NEC that says that.

You know you guys are killing me.

I have miles of 3/0 bare, Cadweld molds for 3/0 to 1/2" rod along with a truck load of shots. How they heck am I going to unload this stuff if I can't get inspectors to require it along with my Kenny clamps and 'Earth entry devices?

:grin::grin: