ground electrode

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weressl said:
How will anyone KNOW without testing, if the second rod installation fulfilled the Code's 25 Ohm requirement?
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It does not have to, once you install the second rod the 25 ohm requirement disappears.
 
I agree with Laszlo?s take on one aspect of this dead horse: the code is unclear. It does not tell us who has the burden of proof. In a practical sense, however, I think the installer would not win a dispute, if the only thing on his side is that the inspector has not proven the resistance is above 25 ohms. What I mean is that if the inspector were to say, ?Show me the resistance test results or install a second rod,? the installer cannot point to a code article that proves the inspector has misinterpreted the requirements. Sad, perhaps, but that?s how I see it.
 
iwire said:
. . . once you install the second rod the 25 ohm requirement disappears.
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I agree. I would also say that this is one of the sillier aspects of the code. I cannot defend it myself, on technical grounds.
 
charlie b said:
I agree. I would also say that this is one of the sillier aspects of the code. I cannot defend it myself, on technical grounds.
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...and that is why the Code's failure is bordering on criminal. It is actually defrauding the people who relies on it to keep them 'safe' from the perils of electricity. Can the Code defend itself on technical merits? Why should they be immune? Just because it is clobbered together by a bunch of autodidacts with corporate interest who overwhelm the technical people on the Code panel(s)? I think the pendulum swung to the other side......
 
This NEC requirement has bothered me for over 30 years. If I were to propose a code change, it may look something like this:

250.56 Installation of Rod Pipe and Plate Electrodes. Where rod, pipe or plate electrodes are utilized, a minimum of two of these electrodes shall be installed and placed no less than 1.8m (6 ft) apart.

Exception: Where a single rod, pipe or plate electrode can be proven to have a resistance to ground of not more than 25 ohms then an additional electrode shall not be required.

I'm also in the camp of folks who still don't know how or why the 25 ohm requirement ended up only in this part of the NEC.​
 
weressl said:
...and that is why the Code's failure is bordering on criminal.
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Now in my personal opinion that is starting to strain your own credibility. (Keeping up my rep. ;) ) It is nowhere near criminal.

The code can be changed by the people that use it and it makes little sense to condemn an entire standard because it has a few sections that need work. :smile:
 
weressl said:
...and that is why the Code's failure is bordering on criminal.
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I don't see this either. Requiring a second rod, without proving it is worth the effort, cannot possibly make the installation less safe.
 
bkludecke said:
If I were to propose a code change, it may look something like this:
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It's not a bad idea. But if I were to test the ground rod for the service at my house on a Seattle Summer Day (translation: hot, and has been dry for weeks), and test again on a Seattle Autumn Day (translation: cool, and has been raining for weeks), I will get very different results. So I would stop the code change recommendation at the part at which it says to install two, and quit there.
 
charlie b said:
If a single rod has a resistance under 25 ohms, it is code compliant. If a single rod has a resistance over 25 ohms, it is not code compliant. If I do not measure the resistance of a single rod, then I do not know whether the installation is code compliant or not. To simply say that it is not compliant is saying more than can be known.
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A single rod, even if the resistance is 5 ohms, without proof, is definitely non-compliant.
 
iwire said:
If you only have a metal water pipe as the electrode for a service you are required to back that up with at least one other electrode of your choice.
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But, if you cannot show 10' continuous feet in contact with earth, you must have two rods.
 
weressl said:
I think it remains the AHJ's responsibility to show that it is not in compliance.
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Sadly, I must disagree with this. Compliance requires either one rod with a below-25-ohm resistance or two rods.

If an inspector can't find two rods (or even one for that matter), you can't say "Prove I haven't installed them."

You'd have to present either one rod and proof of a compliant resistance reading, or you'd have to present two rods.
 
infinity said:
Why not one rod with less than 25 ohms?
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Because, that's why. :cool: Okay, not a good answer. :roll:


Because I can buy a whole bunch of rods than I can buy a ground meter for.
 
LarryFine said:
A single rod, even if the resistance is 5 ohms, without proof, is definitely non-compliant.
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It is no such thing! It may be compliant, and it may not be compliant, and you do not know which of these it is. The words in the NEC, as written, do not support your statement.


That said, if you were to fail the installation, insisting on seeing either the test report or a second rod, I would understand your position. There is a difference between "not being compliant," and "not being able to prove compliance," even though, in a practical sense, they have the same result.
 
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LarryFine said:
Because, that's why. :cool: Okay, not a good answer. :roll:


Because I can buy a whole bunch of rods than I can buy a ground meter for.
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But, the truth is "you must have two rods" is not the truth. :roll:

Roger
 
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