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Thread: Cable Seals 501.15(E)

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    Cable Seals 501.15(E)

    Just need a sanity check to make sure the following statements are true:
    · TC-ER control cable (non-shielded) terminates in factory-sealed 'Start-Stop' PB station –
    No cable seal required based on 501.15(E)(1) and 501.15(E)(3), i.e. may use C-H, CGB, TMC or equal fitting for termination.

    · MC-HL control cable (non-shielded) terminates in NON-Factory-sealed 'Start-Stop' PB station – Cable seal required based on501.15(E)(1) and 501.15(E)(2), i.e. must use C-H, TMCX or equal fitting for termination.
    LNG plant, Class I, Division 2 Gps C&D

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    This is one case where knowing which edition of the NEC you are using would be very helpful. Section 501.15(E) and its Subsections got muddled in 2014. Careful parsing of 501.15(E)(1) is extremely important to interpret the other Subsections correctly.

    That said, Subsection 501.15(E)(3) is useless in any recent edition. It doesn't apply to cable except Type MI which already has its own installation requirements in Section 501.10(A)(1)(b). No manufacturer nor UL will certify any cable, except Type MI, as, "...incapable of transmitting gases or vapors through the cable core."

    It is also important to understand that a factory sealed device's "seal" cannot do "double duty"; i.e., is does not seal the cable.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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    Quote Originally Posted by rbalex View Post
    This is one case where knowing which edition of the NEC you are using would be very helpful. Section 501.15(E) and its Subsections got muddled in 2014. Careful parsing of 501.15(E)(1) is extremely important to interpret the other Subsections correctly.

    That said, Subsection 501.15(E)(3) is useless in any recent edition. It doesn't apply to cable except Type MI which already has its own installation requirements in Section 501.10(A)(1)(b). No manufacturer nor UL will certify any cable, except Type MI, as, "...incapable of transmitting gases or vapors through the cable core."

    It is also important to understand that a factory sealed device's "seal" cannot do "double duty"; i.e., is does not seal the cable.
    Bob, I'm using the 2017 NEC Handbook. What I gather from your last sentence is that the cable still must be sealed even if the control station is factory sealed?

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    Quote Originally Posted by Dale001289 View Post
    Bob, I'm using the 2017 NEC Handbook. What I gather from your last sentence is that the cable still must be sealed even if the control station is factory sealed?
    Definitely don't rely too heavily on the Handbook for classified locations.

    But I'm shamefaced too. It is Section 501.15(E)(2) that is useless rather than Section 501.15(E)(3) but still for the reasons I mentioned before; nothing but Type MI is recognized as restricting gases or vapors through the cable core.

    Here's the deal with Section 501.15(E)(3). The 2017 NEC is much better than the 2014. (That not makes it a lot easier to understand) There is a general exemption from sealing cables with a gas/vaportight continuous sheath in Division 2 unless they are required to be sealed by Section 501.15(E)(1) OR are connected to process equipment or devices capable of exerting pressure on the cable end if the equipment or devices should leak. Section 501.17 deals with leak measures for process equipment. It's rather complex.

    So - in your specific scenario, does Section 501.15(E)(1) require the cable to be sealed, recognizing that a factory seal for the control station doesn't seal the cable?. I would argue that the overall enclosure beyond the factory seal is no longer required to be explosionproof.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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    Quote Originally Posted by rbalex View Post
    Definitely don't rely too heavily on the Handbook for classified locations.

    But I'm shamefaced too. It is Section 501.15(E)(2) that is useless rather than Section 501.15(E)(3) but still for the reasons I mentioned before; nothing but Type MI is recognized as restricting gases or vapors through the cable core.

    Here's the deal with Section 501.15(E)(3). The 2017 NEC is much better than the 2014. (That not makes it a lot easier to understand) There is a general exemption from sealing cables with a gas/vaportight continuous sheath in Division 2 unless they are required to be sealed by Section 501.15(E)(1) OR are connected to process equipment or devices capable of exerting pressure on the cable end if the equipment or devices should leak. Section 501.17 deals with leak measures for process equipment. It's rather complex.

    So - in your specific scenario, does Section 501.15(E)(1) require the cable to be sealed, recognizing that a factory seal for the control station doesn't seal the cable?. I would argue that the overall enclosure beyond the factory seal is no longer required to be explosionproof.
    Thanks Bob for clarification on MI cable. I always thought cables with suffix "-HL", i.e. MC-HL, TC-ER-HL, etc had a core that prevented passage of hazardous vapors, since they are suitable for Division 1 locations.
    Just to be sure, in conclusion: Since the factory sealed control station is not required to be explosionproof, the cable is therefore not required to be sealed per 501.15(E)(1)?

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    Quote Originally Posted by Dale001289 View Post
    Thanks Bob for clarification on MI cable. I always thought cables with suffix "-HL", i.e. MC-HL, TC-ER-HL, etc had a core that prevented passage of hazardous vapors, since they are suitable for Division 1 locations.
    Just to be sure, in conclusion: Since the factory sealed control station is not required to be explosionproof, the cable is therefore not required to be sealed per 501.15(E)(1)?
    In the petro-chem field, we’ve always used MC-HL cable in Division 2. But, I cant see any real advantage over simple MC cable for Div 2 applications. Plus MC-HL costs much more. What am I missing?

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    I was fairly heavily involved with the development of what became MC-HL; a bit less so with what became TC-ER. I will spare most of the details.

    While I was a member of the API SOEE, I suggested and they endorsed and made a Proposal that cable with a gas/vaportight continuous corrugated aluminum sheath, an overall jacket of suitable polymeric material, separate equipment grounding conductors and suitable terminations be accepted in Class I, Division 1. Technically, this was a common form of one of the standard constructions for Type MC [Article 330, Part III in the 2014 NEC; Article 330, Part III in 2017] - until UL got a hold of it. I was one of the primary reviewers of UL's original proposed standard. If the cable were marked as UL originally proposed, it would take a minimum of 9' to accommodate all the text. They settled on "MC-HL" after my comments to that requirement.

    There is nothing in the NEC nor UL Standards that require filling any "-HL" cable to prevent the transmitting of gases/vapors. In fact, it is still a basic "continuous corrugated aluminum" construction, only with a higher price.

    With regard to TC-ER, I was a major proponent. Why anyone felt a need to append "-HL" is beyond me except to jack up the price. It is still the common construction but tested to meet the crush/impact test of Type MC - which most Type TC constructions pass.

    It is important to note TC-ER-HL is only recognized for use in Division 1 as a "flexible connection"; i.e., it is "super duper" - extra-hard usage [See Section 501.140].

    Last, but not least, yep, "Since the factory sealed control station is not required to be explosionproof [at the cable entry], the cable is therefore not required to be sealed per 501.15(E)(1) [and (3)]"
    Last edited by rbalex; 08-02-17 at 06:40 PM. Reason: cleaned up formatting
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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    Quote Originally Posted by rbalex View Post
    I was fairly heavily involved with the development of what became MC-HL; a bit less so with what became TC-ER. I will spare most of the details.

    While I was a member of the API SOEE, I suggested and they endorsed and made a Proposal that cable with a gas/vaportight continuous corrugated aluminum sheath, an overall jacket of suitable polymeric material, separate equipment grounding conductors and suitable terminations be accepted in Class I, Division 1. Technically, this was a common form of one of the standard constructions for Type MC [Article 344, Part C in the 2014 NEC; Article 330, Part III in 2017] - until UL got a hold of it. I was one of the primary reviewers of UL's original proposed standard. If the cable were marked as UL originally proposed, it would take a minimum of 9' to accommodate all the text. They settled on "MC-HL" after my comments to that requirement.

    There is nothing in the NEC nor UL Standards that require filling any "-HL" cable to prevent the transmitting of gases/vapors. In fact, it is still a basic "continuous corrugated aluminum" construction, only with a higher price.

    With regard to TC-ER, I was a major proponent. Why anyone felt a need to append "-HL" is beyond me except to jack up the price. It is still the common construction but tested to meet the crush/impact test of Type MC - which most Type TC constructions pass.

    It is important to note TC-ER-HL is only recognized for use in Division 1 as a "flexible connection"; i.e., it is "super duper" - extra-hard usage [See Section 501.140].

    Last, but not least, yep, "Since the factory sealed control station is not required to be explosionproof [at the cable entry], the cable is therefore not required to be sealed per 501.15(E)(1) [and (3)]"

    Thanks again Bob, great info.

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    Quote Originally Posted by rbalex View Post
    I was fairly heavily involved with the development of what became MC-HL; a bit less so with what became TC-ER. I will spare most of the details.

    While I was a member of the API SOEE, I suggested and they endorsed and made a Proposal that cable with a gas/vaportight continuous corrugated aluminum sheath, an overall jacket of suitable polymeric material, separate equipment grounding conductors and suitable terminations be accepted in Class I, Division 1. Technically, this was a common form of one of the standard constructions for Type MC [Article 344, Part C in the 2014 NEC; Article 330, Part III in 2017] - until UL got a hold of it. I was one of the primary reviewers of UL's original proposed standard. If the cable were marked as UL originally proposed, it would take a minimum of 9' to accommodate all the text. They settled on "MC-HL" after my comments to that requirement.

    There is nothing in the NEC nor UL Standards that require filling any "-HL" cable to prevent the transmitting of gases/vapors. In fact, it is still a basic "continuous corrugated aluminum" construction, only with a higher price.

    With regard to TC-ER, I was a major proponent. Why anyone felt a need to append "-HL" is beyond me except to jack up the price. It is still the common construction but tested to meet the crush/impact test of Type MC - which most Type TC constructions pass.

    It is important to note TC-ER-HL is only recognized for use in Division 1 as a "flexible connection"; i.e., it is "super duper" - extra-hard usage [See Section 501.140].

    Last, but not least, yep, "Since the factory sealed control station is not required to be explosionproof [at the cable entry], the cable is therefore not required to be sealed per 501.15(E)(1) [and (3)]"

    501.15(E) Exception seems to lend any support for using MC-HL vs MC in Division 2.
    “cables with an unbroken gas/vaportight continuous sheath shall be permitted to pass through a Division 2 location without seals”.




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    Quote Originally Posted by Dale001289 View Post
    501.15(E) Exception seems to lend any support for using MC-HL vs MC in Division 2.
    “cables with an unbroken gas/vaportight continuous sheath shall be permitted to pass through a Division 2 location without seals”.
    It depends on which construction of MC you are using; there are three. See Sections 330.2 and 330.116 [2017 NEC]. Type MC-HL is just conventional corrugated metallic sheath Type MC with a higher price tag. In fact, only the "interlocking metal tape armor" construction fails to meet the Exception.

    BTW any form of Type TC is also acceptable. Types TC-ER and TC-ER-HL are also just conventional Type TC costructions that passed the crush and impact tests for Type MC, which almost any Type TC can pass. But "-ER", "-ER-HL", or not, any form of Type TC meets the Exception.

    The "root text" of Section 501.10(B)(1) does not support the mandatory or exclusive use of MC-HL in Division 2. You can certainly use it of course, it simply isn't required.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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