Area controversy around sizing of GEC for ground rod

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roger said:
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
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That's logical reasoning... but the wording of the Code does not support said reasoning. Placing a resistance requirement on the first rod does not change the fact that it is an electrode. 250.52(A)(5) "defines" a Code-recognized rod electrode, while 250.53(G) describes its installation, and neither say anything about two being considered one where two are installed to comply with 250.56. As I said, nowhere in Article 250 does it say two installed electrodes can be considered one. Reasoning otherwise by implicit deduction is your perogative... but that don't make it code.
 
Do you all really think the NEC gets this technical in the wording of the NEC. Golly if we have half the people here seeing something one way and the others see it differently then , IMO, there is a problem. I think we are over thinking this, :) But it is an education to say the least. Why is English so hard- I wonder if other languages are this difficult to convey what they what to say.
 
Simply: there's no earthly (pun intended) reason for a jumper between two rods to be any larger than the GEC between the service and the rods.
 
LarryFine said:
Simply: there's no earthly (pun intended) reason for a jumper between two rods to be any larger than the GEC between the service and the rods.
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I agree... but the wording doesn't permit a #6 GEC (if Table size is larger) to the first rod if the second rod is jumpered (i.e. two connections at the first rod). So a Table sized GEc would be required to the first, and a Table-sized jumper would not be larger than the GEC between service and rod. It's that sole connection part of 250.66(A) which screws it up. ;)
 
Smart $ said:
What say ye all to the interpretation depicted in the lower image...???
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I think it hit the nail on the head. Although I see no reason for the bonding jumper in the first pic to be bigger as the code wording seems to indicate.
 
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iwire said:
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.
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No 25 ohm requirement for a multiple-rod electrode:
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
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Dennis Alwon said:
I think we are over thinking this, :) But it is an education to say the least.
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Oh yeah. But I have really enjoyed reading it. It makes you realize how such a simple thing can turn out to not be so simple. A great lesson in technical writing.
 
iwire said:
There in no such thing as a multiple-rod 'single' electrode.
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Since we are going to be all technical and what-not ;):
250.52 Grounding Electrodes
(2) Metal Frame of the Building or Structure.
The metal frame of the building or structure that is connected to the earth by any of the following methods...(3) Bonding the structural metal frame to one or more of the grounding electrodes...
...
(3) Concrete-Encased Electrode.
...consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods...
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Not to mention electrodes with rods that are joined together for a longer length.

But I get what you are saying. Put the rods in series and they are called one electrode, parallel them with sufficient spacing and they are called a system.
 
Smart $ said:
That's logical reasoning... but the wording of the Code does not support said reasoning. Placing a resistance requirement on the first rod does not change the fact that it is an electrode. 250.52(A)(5) "defines" a Code-recognized rod electrode, while 250.53(G) describes its installation, and neither say anything about two being considered one where two are installed to comply with 250.56. As I said, nowhere in Article 250 does it say two installed electrodes can be considered one. Reasoning otherwise by implicit deduction is your perogative... but that don't make it code.
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Determining something is code versus determining something is common sense are two different things. Clearly why if is an interpretation and a ruling by local AHJ.
 
iwire said:
There in no such thing as a multiple-rod 'single' electrode.
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i think that clearly adding the additional electrode to the first ground rod does not make a multiple rod electrode but it does complete a grounding electrode system in this case. The problem is that I can see where it gets screwy in that clearly the sole connection to the first electrode (the first rod ) is not required to be larger than the 6 AWG. The problem starts when it says size the bonding jumper per 250.66 and the table gets used and so it becomes a situation where the bonding jumper from rod 1 to rod 2 is no longer a GEC . In this case I can see where someone can argue that the bonding jumper run to the second electrode cant use 250.66(A) and could lead to a larger bonding jumper.

However, I don't think this is the intent as I am quite sure lightning could careless but alas I am not engineer.
 
roger said:
Here are a couple of pertainent ROP's, since the forum does not support strike throughs the bold "electrode(s)" was the proposed change in the first.









Roger
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Roger,
For fun I sent for an informal opinion from the NFPA to see if they are on the same page. I know, it's informal and its not the CMP but hey....I always like to see. I agree in that #6 AWG should be all that is required but like iwire has stated and how it has been debated here......many opinions vary.
 
radiopet said:
The problem starts when it says size the bonding jumper per 250.66 and the table gets used and so it becomes a situation where the bonding jumper from rod 1 to rod 2 is no longer a GEC.
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In my opinion, the jumper is "the sole connection" to the second rod, and the #6 limit applies.

Added:
......many opinions vary.
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Wouldn't one need many opinions for them to vary? :grin:
 
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LarryFine said:
In my opinion, the jumper is "the sole connection" to the second rod, and the #6 limit applies.

Added: Wouldn't one need many opinions for them to vary? :grin:
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lol....well considering we have varied opinions here I guess it would apply. interesting enough i like many tend to give our opinion to what the intent actually was only to post what the code actually says ...and then it gets all mixed up..;)

BTW...how are things going in Richmond....doing ok?
 
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