NC Dept of Insurance Official Interpretations

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Dennis Alwon

Dennis Alwon

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If anyone wants a copy of NCDOI official interpretation of some commonly disputed sections in the 2017 NEC then click on the link below. I advise you to download it into word and the links should work. The links just take you to other areas of the document. Move your mouse to the link then use ctrl and click to activate the link.

NCDOI Formal Interpretation
 
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Dennis Alwon said:
Why didn't you fix it? lol

Thanks I got it
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:D

I found this question and answer interesting:

Question 2:
If a metal underground water pipe is used as part of an electrode system and is supplemented with a ground rod, is another grounding electrode required to supplement the supplemented ground rod?

Answer 2:
No. The requirement of section 250.53(D)(2) requires one supplement electrode of a type chosen from sections 250.52(A)(2) through (A)(8), in which a rod is listed in section 250.52(A)(5).
Both the water pipe and the rod must comply with the installation requirements of section 250.53(A). Because the water pipe and the rod make two electrodes, each supplement the other; thus, 250.53(A)(2) is satisfied.
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infinity said:
:D

I found this question and answer interesting:
Question 2:
If a metal underground water pipe is used as part of an electrode system and is supplemented with a ground rod, is another grounding electrode required to supplement the supplemented ground rod?

Answer 2:
No. The requirement of section 250.53(D)(2) requires one supplement electrode of a type chosen from sections 250.52(A)(2) through (A)(8), in which a rod is listed in section 250.52(A)(5).
Both the water pipe and the rod must comply with the installation requirements of section 250.53(A). Because the water pipe and the rod make two electrodes, each supplement the other; thus, 250.53(A)(2) is satisfied.
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Oooo. I LIKE it.
 
Not sure how a water pipe is supplementing a single ground rod when the water pipe gets changed to plastic.
 
infinity said:
Not sure how a water pipe is supplementing a single ground rod when the water pipe gets changed to plastic.
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It's not, in fact, the rod is really only supplementing the water line specifically for that reason. When the electrode becomes plastic then the rod is still there. So technically if they change the copper pipe to plastic then one should have to add another rod.
 
Dennis Alwon said:
It's not, in fact, the rod is really only supplementing the water line specifically for that reason. When the electrode becomes plastic then the rod is still there. So technically if they change the copper pipe to plastic then one should have to add another rod.
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Exactly that's why I disagree with their response to the question unless the single rod is 25 ohms or less.
 
ptonsparky said:
I thought we’re werent supposed to worry about future ‘what ifs’ ? We would never get done.
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The NCDOI can interpret the code and make a formal decision as to how something is interpreted. You are correct that we should use what iof scenarios but that may be just a reason as to why their interpretation makes sense.
 
infinity said:
How does a single rod without a resistance of 25 ohms or less qualify as an electrode?
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Where does it say that?

Question 1:
If only ground rods are used as an electrode system for a single family dwelling, are two required?

Answer 1:
Single electrodes made of rod, pipe, or steel plates must have a resistance to ground of 25 ohms or less, or must be augmented by an additional electrode of a type specified by section 250.52(A)(2) through (A)(7). The installer is required to assure the system meets this requirement and submit proof that is acceptable to the local electrical inspector.
Note: In extensive testing throughout North Carolina soil conditions have found to be of types prohibiting conductivity meeting the 25 ohms or less requirement for resistance.

Question 2:
If a metal underground water pipe is used as part of an electrode system and is supplemented with a ground rod, is another grounding electrode required to supplement the supplemented ground rod?

Answer 2:
No. The requirement of section 250.53(D)(2) requires one supplement electrode of a type chosen from sections 250.52(A)(2) through (A)(8), in which a rod is listed in section 250.52(A)(5).
Both the water pipe and the rod must comply with the installation requirements of section 250.53(A). Because the water pipe and the rod make two electrodes, each supplement the other; thus, 250.53(A)(2) is satisfied.
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I disagree with their answer for the for the following reasons section 250.53 D(2) requires the supplemental grounding electrode but also states a rod, pipe or plate must comply with 250.53A and there it states a single rod must be supplemented by an additional electrode, excluding water pipe, or meet the 25 ohm requirement.
250.53 Grounding Electrode System Installation.
A (2) Supplemental Electrode Required. A single rod, pipe,
or plate electrode shall be supplemented by an additional
electrode of a type specified in 250.52(A)(2) through
(A)(8). The supplemental electrode shall be permitted to be
bonded to one of the following:
(1) Rod, pipe, or plate electrode
(2) Grounding electrode conductor
(3) Grounded service-entrance conductor
(4) Nonflexible grounded service raceway
(5) Any grounded service enclosure
Exception: If a single rod, pipe, or plate grounding electrode
has a resistance to earth of 25 ohms or less, the
supplemental electrode shall not be required.

(D) Metal Underground Water Pipe. If used as a grounding
electrode, metal underground water pipe shall meet the
requirements of 250.53(D)(1) and (D)(2).
(2) Supplemental Electrode Required. A metal underground
water pipe shall be supplemented by an additional
electrode of a type specified in 250.52(A)(2) through
(A)(8). If the supplemental electrode is of the rod, pipe, or
plate type, it shall comply with 250.53(A).
supplemental electrode shall not be required.
 
I am not seeing what is wrong. You can have 2 rods or if there is a water pipe (assuming that it is an electrode, of course) you must bond it and then add an additional electrode which is usually a rod.

Is that not what is being said?
 
infinity said:
How does a single rod without a resistance of 25 ohms or less qualify as an electrode?
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Dennis Alwon said:
Where does it say that?
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I'm referring to question #2 in your post not question #1. The response to question #2 allows a single rod to supplement the water pipe and the water pipe to supplement the single rod. A single rod is not considered an electrode unless you supplement it or can prove it's 25 ohms or less.

Rick summed up the code sections nicely. :)
 
infinity said:
I'm referring to question #2 in your post not question #1. The response to question #2 allows a single rod to supplement the water pipe and the water pipe to supplement the single rod. A single rod is not considered an electrode unless you supplement it or can prove it's 25 ohms or less.
:)
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Yes that was the point I was trying to make.
 
Around here, when we perform an upgrade, unless there is a way to make certain the water pipe has the required ground contact, we must use two rods.
 
infinity said:
I'm referring to question #2 in your post not question #1. The response to question #2 allows a single rod to supplement the water pipe and the water pipe to supplement the single rod. A single rod is not considered an electrode unless you supplement it or can prove it's 25 ohms or less.

Rick summed up the code sections nicely. :)
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So what is it the terminology? If the water pipe and the rod are both bonded then it is compliant. What is the issue other than wording.
 
Dennis Alwon said:
So what is it the terminology? If the water pipe and the rod are both bonded then it is compliant. What is the issue other than wording.
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Here is what I see as the problem in the response to question #2:

Because the water pipe and the rod make two electrodes, each supplement the other; thus, 250.53(A)(2) is satisfied.
Click to expand...
 
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