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Thread: Class 2 div 2 conduit and sealing

  1. #1
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    Class 2 div 2 conduit and sealing

    As I read the code for Class 2 Div 2, I read that EMT is allowed. I would assume only with compression type fittings to remain dust tight. Do my entrys into the junction boxes and control panels need to be sealed within this area? If so, can a gasket be used as a seal?

  2. #2
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    EMT with compression fittings is suitable for Class II,Division 2.

    Sealing is dependent on the enclosure type, whether Division1 or 2:
    · Dust-ignitionproof enclosures shall be “sealed” per 502.15.
    · Dusttight enclosures are not required to besealed.

    Enclosures must be dusttight or dust-ignitionproof, as necessary, without a gasket.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  3. #3
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    Wouldn't EMT only be allowed for nonincendive circuits though?

  4. #4
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    Quote Originally Posted by WesR View Post
    Wouldn't EMT only be allowed for nonincendive circuits though?
    See Section 502.10(B)(1)(2).
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  5. #5
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    Oh I see, I was thinking Class 1 for some reason. For Class 1 Div 2, the circuit would need to be nonincendive, right?

  6. #6
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    Quote Originally Posted by WesR View Post
    Oh I see, I was thinking Class 1 for some reason. For Class 1 Div 2, the circuit would need to be nonincendive, right?
    Yes; in Class I, Division 2 the circuit would need to be nonincendive (or intrinsically safe) to use EMT as a wiring method.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  7. #7
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    501.15(B)(2) Exception No. 1 - This basically says that seals are not required between the Class 1 Div 2 region and unclassified region if the conduit is unbroken in all classified regions, right? In such a case, are the wiring methods for Class 1 Div 2 still applicable? Could this unbroken conduit be EMT? Exception No. 1 does use the wording "metal conduit" after all, no mention of threaded.

    EDIT: And, if breaks in the conduit are at least one foot beyond the boundary into the unclassified region. - Is this the correct interpretation of the fitting stipulation of Exception No. 1?
    Last edited by WesR; 06-13-12 at 01:09 PM.

  8. #8
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    Quote Originally Posted by WesR View Post
    501.15(B)(2) Exception No. 1 - This basically says that seals are not required between the Class 1 Div 2 region and unclassified region if the conduit is unbroken in all classified regions, right? In such a case, are the wiring methods for Class 1 Div 2 still applicable? Could this unbroken conduit be EMT? Exception No. 1 does use the wording "metal conduit" after all, no mention of threaded.

    EDIT: And, if breaks in the conduit are at least one foot beyond the boundary into the unclassified region. - Is this the correct interpretation of the fitting stipulation of Exception No. 1?
    There are a several considerations here.

    First, within context, the Section 501.15(B)(2 Exceptions are intended to apply to the location or possible absence of Division 2 boundary seals under specific applications; not the wiring methods.

    Second, an Exception only applies to its main text. Therefore, 501.15(B)(2) Exception No. 1 does not apply wholesale to the rest of Article 501; it can only apply to conduits referred to in the main text of Section 501.15(B)(2); i.e., rigid metal conduit and threaded steel intermediate metal conduit.

    Third, 501.10 (B) defines acceptable wiring methods in Division 2 – with or without defining seal locations. EMT is not permitted in Division 2 except for nonincendive or intrinsically safe wiring.

    Fourth, an installation must meet all requirements; inconsistencies are not necessarily contradictions.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  9. #9
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    Thank you for the insight!

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