250.92(B) Method of Bonding at the Service (2017 NEC)

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PCBelarge

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In the first paragraph of the above Section 250.92(B), "such as reducing washers" is included as part of the methods.

UL Whitebook- (QCRV) states, under the paragraph titled "Grounding," Metal reducing washers - "for non-service conductors only."

I looked back to the '08 NEC and see the same wording. Is this an oversight and maybe no one has read this part of UL's document? As I read it, metal reducing washers are not permitted wherever service conductors are installed. I have been teaching the guys the same for years. I believe that UL does not permit this due to the amount of energy during a fault condition, melting the washers??
 
UL (QCRV) specifically mandates they cannot be used where service conductors are installed.
Every time a person reading the NEC sees the words, listed, listing, list, or an electrical product - I ask them to tell me what it really means. UL has the document that goes hand-in-hand with the NEC. UL "instructions, do not permit the use of metal reducing washers where service conductors are installed.
Without it, there are too many times the installer/designer/inspectors do not really know what to look for.
The same is in the question I am asking.

In saying the above, I believe 'reducing washers' should be removed from this subsection.
 
I read the language in the UL Guide Information as only prohibiting the use of reducing washers for grounding or bonding purposes when used with raceways containing service conductors. I don't see it as saying you can't use them for that application. It appears the the Guide Information and the code rule are in agreement.
GROUNDING
Metal reducing washers are considered suitable for grounding for use in circuits over and under 250 V and where installed in accordance with NFPA 70, "National Electrical Code," for raceways containing other than service conductors. Reducing washers are intended for use with metal enclosures having a minimum thickness of 0.053 in. Reducing washers may be installed in enclosures provided with concentric or eccentric knockouts, only after all of the concentric and eccentric rings have been removed. However, those enclosures containing concentric and eccentric knockouts that have been certified for bonding purposes may be used with reducing washers without all knockouts being removed.
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don_resqcapt19 said:
I read the language in the UL Guide Information as only prohibiting the use of reducing washers for grounding or bonding purposes when used with raceways containing service conductors. I don't see it as saying you can't use them for that application. It appears the the Guide Information and the code rule are in agreement.
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Don,
Here is the actual language used. Lets discuss how you and I read this differently. I respect your knowledge, so hopefully, we can agree.

"Metal reducing washers are considered suitable for grounding for the use in circuits over and under 250v and where installed in accordance with ANSI/NFPA 70, 'National Electrical Code." Reducing washers are intended for use with metal enclosures having a minimum thickness of 0.053 in. for non-service conductors only."


I do not think the rest of the wording that follows the sentence in red, is necessary to determine whether or not they can or cannot be used where service conductors are installed.

The punctuation prior to the sentence I have in red, separates it from the prior wording, which includes the bonding you mentioned. That is how I read it.
Let me know what you think. Thanks.
 
PCBelarge said:
Don,
Here is the actual language used. Lets discuss how you and I read this differently. I respect your knowledge, so hopefully, we can agree.

"Metal reducing washers are considered suitable for grounding for the use in circuits over and under 250v and where installed in accordance with ANSI/NFPA 70, 'National Electrical Code." Reducing washers are intended for use with metal enclosures having a minimum thickness of 0.053 in. for non-service conductors only."


I do not think the rest of the wording that follows the sentence in red, is necessary to determine whether or not they can or cannot be used where service conductors are installed.

The punctuation prior to the sentence I have in red, separates it from the prior wording, which includes the bonding you mentioned. That is how I read it.
Let me know what you think. Thanks.
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Just like the code you have to look to the title of the section. The titles limit the application of the language that follows. That section is titled "grounding" and only prohibits the used of reducing washers for grounding purposes when the raceway contains service conductors.

(at least that is how I read the Guide Information and code sections)
 
don_resqcapt19 said:
Just like the code you have to look to the title of the section. The titles limit the application of the language that follows. That section is titled "grounding" and only prohibits the used of reducing washers for grounding purposes when the raceway contains service conductors.

(at least that is how I read the Guide Information and code sections)
Click to expand...
Don,
I have applied this process with the NEC, not with the Whitebook. I am pretty sure you are correct. Thanks for the extra set of eyes.
 
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