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Thread: Classified Location Bonding

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    Classified Location Bonding

    I have a customer inspector who claims the smallest size bonding jumper in a classified area is #8 per the following logic. I don't agree, I believe Table 250.122 can be used to size the bonding conductor, what is correct?

    As per ourdiscussion on the bonding wire size of hubs and doors.

    2017 NEC 250.100 Bonding in Hazardous(Classified) Locations.
    Regardless of the voltage of the electricalsystem, the electrical continuity of non–current-carrying metal parts ofequipment, raceways, and other enclosures in any hazardous (classified)location, as defined in 500.5, 505.5, and 506.5, shall be ensured by any of thebonding methods specified in 250.92(B)(2) through (B)(4). One or more ofthese bonding methods shall be used whether or not equipment groundingconductors of the wire type are installed.
    2017 NEC 250.92 Services. Because the reference is under "Services", Table250.102(C)(1) is used to determine the smallest bonding jumper that can be usedto be #8.

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    Quote Originally Posted by Jim1959 View Post
    I have a customer inspector who claims the smallest size bonding jumper in a classified area is #8 per the following logic. I don't agree, I believe Table 250.122 can be used to size the bonding conductor, what is correct?

    As per ourdiscussion on the bonding wire size of hubs and doors.

    2017 NEC 250.100 Bonding in Hazardous(Classified) Locations.
    Regardless of the voltage of the electricalsystem, the electrical continuity of non–current-carrying metal parts ofequipment, raceways, and other enclosures in any hazardous (classified)location, as defined in 500.5, 505.5, and 506.5, shall be ensured by any of thebonding methods specified in 250.92(B)(2) through (B)(4). One or more ofthese bonding methods shall be used whether or not equipment groundingconductors of the wire type are installed.
    2017 NEC 250.92 Services. Because the reference is under "Services", Table250.102(C)(1) is used to determine the smallest bonding jumper that can be usedto be #8.
    Can you provide more specifics? A wire bonding jumper is only required for impaired connections. I actually read the references to preclude any impaired connections. So a wire type bonding jumper would not be allowed, let alone required.


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    Wow, this is funny, I have this same issue today as well with a large Colorado client as well.

    I think this is what the OP is referring to.

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    Last edited by MrJLH; 03-26-19 at 12:49 PM.

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    Another question is does 250.100 apply to non-service equipment?

    I'm not sure if this is true or not.

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    I understand the inspector's argument - and disagree with it. It is a case of one CMP unintentionally stepping a bit on the toes of another.

    You will note neither Section 501.30(A) nor any other text in Section 501.30 mentions Section 250.100 - not even in an Informational Note. However, Section 250.102 is referred to in Section 501.30(B) which references a specific application for equipment bonding jumpers. CMP14 is aware of 250.100 and recognizes the general application of the methods noted in Section 250.92(B)(2) through (B)(4) but does not believe it declares that it requires service requirements be applied to general equipment bonding - otherwise it would specifically state so.

    You will also note, Section 250.100 Informational Note does reference various Chapter 5 grounding sections for specific bonding requirements.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2017 NEC unless otherwise noted.

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    Quote Originally Posted by MrJLH View Post
    Another question is does 250.100 apply to non-service equipment?

    I'm not sure if this is true or not.
    Regarding this it is an easy answer. Yes it does apply. 250.100 is a subsection of Part V. Bonding, not 250.92 Services. Regarding the size, it seems to me that table 250.102 shouldn't apply because it is specifically not for equipment bonding jumpers, however, since it is ambiguous, I would not likely argue with an Authority on the issue.


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    Quote Originally Posted by rbalex View Post
    I understand the inspector's argument - and disagree with it. It is a case of one CMP unintentionally stepping a bit on the toes of another.

    You will note neither Section 501.30(A) nor any other text in Section 501.30 mentions Section 250.100 - not even in an Informational Note. However, Section 250.102 is referred to in Section 501.30(B) which references a specific application for equipment bonding jumpers. CMP14 is aware of 250.100 and recognizes the general application of the methods noted in Section 250.92(B)(2) through (B)(4) but does not believe it declares that it requires service requirements be applied to general equipment bonding - otherwise it would specifically state so.

    You will also note, Section 250.100 Informational Note does reference various Chapter 5 grounding sections for specific bonding requirements.
    I can see a lot of what you said about one CMP stepping on another's toes.

    After reading through all the code sections that get mentioned both in regular code text and in informational notes- is seems fairly clear they want similar bonding in hazardous locations as they do at services - in particular not using standard locknuts as the sole bonding means.

    I see nothing in there that suggests you must use anything other than 250.122 for sizing the conductor as long as what is involved is not service enclosures/raceways.
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