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Thread: Class 1 Div 2 guidance on sealing the conduits

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    Class 1 Div 2 guidance on sealing the conduits

    Dear Forum:

    We are struggling with clearly explaining the electrical code when it comes to class 1 div 2 seals. Our understanding is that in areas where a fitting is not required and you are required to stop gas we have a product that is UL and meets the code for not allowing gas to pass through it. This should then be code compliant. It is only when a fitting is required that they can not just seal the conduit with our product. Is this correct?

    Secondly, in a class 1 div 2 area where a fitting is required can they use any type of a sealant to stop gas rather than what that fitting was tested with in a class 1 div 1 area?

    Finally, could you give some common examples of where class 1 div 2 locations would be at a waste water treatment plant, gas station, etc? Please.

    Thank you so much for your help.

    Tom

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    Start with Section 501.15 Informational Note No.1. The first sentence declares the purpose of seals in Class I locations regardless of the Division. Explosionproof seals are required to prevent the passage of flames. Nonexplosioproof seals are permitted only where minimizing (not preventing) the passage of gasses is the only requirement.

    The only place nonexplosionproof seals are mentioned specifically for Class I, Division 2 is the last sentence of Section 501.15(B) at boundaries. NOTE: Such seals may still need to be explosionproof if they are doing "double-duty" as an explosionproof enclosure seal.

    See NFPA 820, Tables 4.2.2, 5.2.2, and 6.2.2(a) for examples of Class I, Division 2 locations in wastewater facilities. See Section 514.3 for classifying gas stations. See Section 500.4(B), Informational Note No.2, especially NFPA 497 and API RP 500 for other examples of Class I, Division 2 locations.

    There are other places where nonexplosionproof seals are permitted such as Section 504.70.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2017 NEC unless otherwise noted.

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    Quote Originally Posted by freddyt7 View Post
    ...
    Secondly, in a class 1 div 2 area where a fitting is required can they use any type of a sealant to stop gas rather than what that fitting was tested with in a class 1 div 1 area?
    ...
    I note I didn't really address this. This is because I don't think the NEC has addressed it either. Section 501.15(C) covers the requirements for seals, but the Exception pretty much wipes out all requirements for nonexplosionproof seals. I know how I would approach such a situation [Section 500.8(A)(3)], but I couldn't guarantee AHJ acceptance - even if UL said it meets the Code.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2017 NEC unless otherwise noted.

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