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Thread: Type MC-HL Cable

  1. #1

    Type MC-HL Cable

    501.4(A)(1)(c) allows the use of listed Type MC-HL cable (instead of conduit) in some Cl 1 Div 1 hazardous locations.

    Is "MC-HL" a UL designation? I've found one MC-HL cable from General Cable. Is anyone aware of other manufacturers? Has anyone designed/installed any Cl 1 Div 1 haz-location systems using this method instead of RMC with sealing fittings?

  2. #2
    Join Date
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    Re: Type MC-HL Cable

    Is "MC-HL" a UL designation? - YES

    I've found one MC-HL cable from General Cable. Is anyone aware of other manufacturers? - YES, Okonite - Type CLX. Canada Wire & Cable does also. Any Type MC with a "continuously corrugated" outer sheath will probably meet the requirements.

    Has anyone designed/installed any Cl I Div 1 haz-location systems using this method instead of RMC with sealing fittings?- YES and it works well. It is in common use on offshore drilling platforms.
    "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

    Re: Type MC-HL Cable

    Thanks Bob. Most of our work with gas utilities still uses Rigid Conduit with EY-type seal fittings. I haven't seen any CL1 Div 1 installations with the MC-HL cable.

    I also came across the CLX cable after I posted.

    While any Type MC cable would likely meet the requirements, I'd suspect the AHJ would require the "MC-HL" listing. That's what I was having trouble locating.

  4. #4
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    Re: Type MC-HL Cable

    I should have added "... an overall jacket of suitable polymeric material (PVC ) and separate grounding conductors."

    If that is the MC construction, odds are very high that it will be marked "MC-HL." This is actually a common MC construction and most manufacturers that make it will get it listed that way. The "critical" element is the terminations - not the cable.
    "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
    Join Date
    Nov 2004
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    Re: Type MC-HL Cable

    We use a lot, mostly Okonite CLX. Not only for classified areas, but a lot for underground. It doesn't have any of the problems associated with RSC.

    Another big issue is for installations on a separately derived system. Grounding conductor is required to be sized per 250.66. For most MC cable, the grounding conductor is sized for the biggest CB that would normally be protecting that size conductor (250.122). That is generally too small for 250.66. Continous sheath MC per 250.118(11) (2002 Code) allows the AL sheath to be included with the internal grounding conductors for use as THE grounding conductor. And that is way over the requirements of 250.66. Okonite CLX meets these requirements and it is stocked.

    Plenty of other mfgs show it in their catalog/website, but don't stock any. Rockbestos Gardex may be an exception. The specs look good. I have a call into them to see if and where thay stock any. It would be nice to have an alternate.

    carl
    Using the code for a design guide is a sign of incompetance

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