Depends on how the 2 rods are connected. As I mentioned earlier, #6 is good when it is a sole connection to the rod. If the conductor connects both rods, then it must be sized per Table 250.66, at least for the portion to the first rod.
bonding copper water pipe
- Thread starter novemberaudi
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Disregard this. I think this would cause the service GEC to be upsized if it is currently only a #6 because it would no longer be the sole connection to the ground rods.
Trying to understand. 250.66(A) seems confusing. Haven't quite grasped it yet.
So if the GEC goes from the service panel to the first ground rod with a clamp, then continues onto a 2nd rod, it can no longer be a #6? Is this because both the panel and the 2nd ground rod is connected to the first rod even though the GEC is typically continuous?
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jxofaltrds
Inspector Mike®
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Not true.
250.64
(F) Installation to Electrode(s). Grounding electrode conductor(s) and bonding jumpers interconnecting grounding
electrodes shall be installed in accordance with (1), (2), or (3). The grounding electrode conductor shall be sized for
the largest grounding electrode conductor required among all the electrodes connected to it.
250.66
(A) Connections to Rod, Pipe, or Plate Electrodes.
Where the grounding electrode conductor is connected to rod, pipe, or plate electrodes as permitted in 250.52(A)(5)
or (A)(7), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum wire
250.53
(E) Supplemental Electrode Bonding Connection Size.
Where the supplemental electrode is a rod, pipe, or plate electrode, that portion of the bonding jumper that is the sole
connection to the supplemental grounding electrode shall not be required to be larger than 6 AWG copper wire or 4
AWG aluminum wire.
You have a sole conductor going to the first rod. THEN you have a sole conductor (bonding jumper) going to a supplemental rod.
You have ONE GEC and ONE Bonding Jumper.
jxofaltrds
Inspector Mike®
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- Mike P. Columbus Ohio
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- ESI, PI, RBO
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The part you left out of your highlights is "that portion of the conductor that is the sole connection to the grounding electrode".
Take the depiction you posted as an example...
View attachment 9537
The GEC to the first rod is NOT a sole connection to the rod. There are two connections to the first rod, the GEC and the bonding jumper.
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I would disagree. The grounding electrode in this case is the two rods acting together not just the first rod.
I was wondering how long it would take for someone to present that argument in the debate... :lol:
Either way, its a no-win debate. :thumbsdown:
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No debate, need two rods to form the electrode.
I thought that the 2014 had added some wording to clear this up. Might have been a proposal from someone here on the forum.
I don't see the NEC wording supporting that conclusion, so we'll have to agree to disagree... and see if 2014 changes that :blink:.No debate, need two rods to form the electrode.
I thought that the 2014 had added some wording to clear this up. Might have been a proposal from someone here on the forum.
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One problem as I see it is that the code talks about "...is the sole connection to the ground rod" when it actually means "connects solely to the ground rod". That makes a big difference, and IMHO would resolve a lot of the confusion.
Anybody who wants to public comment that (no proposals anymore) is welcome to run with it.
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Anybody who wants to public comment that (no proposals anymore) is welcome to run with it.
Sent from my XT1080 using Tapatalk
While I understand what you are conveying, you actually misquoted the text. It says "that portion of the conductor that is the sole connection to the grounding electrode". Additionally, the title uses the plural form of key words:One problem as I see it is that the code talks about "...is the sole connection to the ground rod" when it actually means "connects solely to the ground rod". That makes a big difference, and IMHO would resolve a lot of the confusion.
Anybody who wants to public comment that (no proposals anymore) is welcome to run with it.
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and the first part of the sentence repeats it:
It would be less confusing to use the singular form of these words, provided that is the intent.
I would rather the middle part say:
Because the first part of the sentence uses grounding electrode conductor, this would eliminate the confusion where a bonding jumper (which many do not consider a GEC) is used to connect from one electrode to another... or another way would be to add bonding jumper to the first part of the sentence.
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- Retired PV System Designer
You got me there. I trusted that earlier posters had quoted the code correctly instead of double checking it myself.
The wording does, as you note, leave some doubts about conductors that connect solely to a set of ground rods only rather than to a single ground rod only. In terms of safety and performance the result intended by the CMP could be either way.
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The wording does, as you note, leave some doubts about conductors that connect solely to a set of ground rods only rather than to a single ground rod only. In terms of safety and performance the result intended by the CMP could be either way.
Sent from my XT1080 using Tapatalk
True, but if you consider each rod as a load, it stands to reason that two connected rods will require a larger conductor.You got me there. I trusted that earlier posters had quoted the code correctly instead of double checking it myself.
The wording does, as you note, leave some doubts about conductors that connect solely to a set of ground rods only rather than to a single ground rod only. In terms of safety and performance the result intended by the CMP could be either way.
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- Placerville, CA, USA
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- Retired PV System Designer
True, but only to the extent that their zones of influence are far enough apart, and also given that they may still be 25 ohms or worse in total.
My take is that two rods are not that much better than one rod in terms of carrying the amount of current that a #6 wire can handle.
But a plate, water pipe or Ufer concrete encased electrode could do a lot better.
The whole thing (sizing the GEC) seems to be intimately tied in with the notion of the ground electrode as a fault clearing path, which is off base to start with. But that has been well covered in other threads and MH videos.
The way I look at it, the GEC does not need to be particularly large no matter the service size as long as it is not also part of the fault clearing path (e.g EGC).
To get 90 amps flowing through the GEC to a 25 ohm electrode would require a 2,250V to ground volt service. Not very common in residential environments.
For the most part I agree. Too many variables beyond human control. Even regarding other types of electrodes we make assumptions. Circumstances for a certain scenario could result in a CCE having a higher resistance than a rod, making a full sized GEC extraneous.
FWIW, I never look at the GES as being a ground-fault-clearing path. I only consider it a path for lightning-induced surges.
jxofaltrds
Inspector Mike®
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- Mike P. Columbus Ohio
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- ESI, PI, RBO
It all has to do with surface arcing. I wish I had the ability to explain it to you.
The lower the resistance to earth the less likely surface arcing is to occur.
If the cable guy adds a wire to a ground rod do you increase the EGC because it is now not the only connection? No.
The lower the resistance to earth the less likely surface arcing is to occur.
If the cable guy adds a wire to a ground rod do you increase the EGC because it is now not the only connection? No.
kwired
Electron manager
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Why is he running to the ground rod? We are supposed to provide him with an intersystem bonding termination
I still see them running grounding leads to AC disconnects, sillcocks (that have non metallic piping supplying them:roll
wrap the conductor around a set screw for a raceway or cable fitting and any other grounded item imaginable, even if there is an intersystem bonding termination point there for them to use.
jxofaltrds
Inspector Mike®
- Location
- Mike P. Columbus Ohio
- Occupation
- ESI, PI, RBO
Why is he running to the ground rod? We are supposed to provide him with an intersystem bonding termination
I still see them running grounding leads to AC disconnects, sillcocks (that have non metallic piping supplying them:roll
YES all the time We see this!
Checked my own house this past weekend and sure enough, the copper lines were not bonded, couldn't believe it. My house is not very old either; suprized this wasen't cought (I'm not the original owner). Before bonding, I checked for mV AC at my electric water tank copper lines. I checked it to a receptacle in the area ground. There was about 220mV on it. I turned off the water heater and that levle went down some. Proceeded to bond across the hot and cold at the water tank and across the in/out of my water softener. My GEC was #4 based on the diameter with a dial indicator so i took the bond from my water line by my panel to the GEC with a split bolt. Worked out quite well. I then checked continuity at my water heater to the same receptace and got good continuity. I then checked mV again and it was about 8mV AC. I guee my only concern now is why was there mV on my water line and now that I grounded it, will I get problem with pinhole leaks in my copper lines because the voltage is flowing per say, not just present as before?
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