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Thread: LMFC in Class I, Div 2 Gr B

  1. #1
    Join Date
    Mar 2017
    Location
    NC
    Posts
    1

    LMFC in Class I, Div 2 Gr B

    A few decades ago, I was taught that you never flex to a control panel. It is fixed in place. It does not require vibration isolation. Therefore, run conduit to the panel. This was a blanket statement and no one ever suggested that it was incorrect. (As an apprentice, I did not challenge the statement.)

    Fast forward 30 years. I was talking with an electrical engineer about replacing an instrument enclosure.

    This particular enclosure had three 1" runs of LMFC. In addition, there were several other code violations. I commented on the code violations. In the list, I included "flexing to a control panel." He stated that the flex was not a code violation. (He agreed with the other items.) I made the statement about a control panel is fixed in place and, therefore, you do not flex to the panel.

    Since this is a Class I, Div 2 location, I looked in Section 500. 501.10(B)(2) states:
    Flexible Connections. Where provision must be made
    for flexibility
    ,
    one or more of the following shall be permitted: [Emphasis added]
    (1) Listed flexible metal fittings.
    (2) Flexible metal conduit with listed fittings.
    (3) Interlocked armor Type MC cable with listed fittings.
    (4) Liquidtight flexible metal conduit with listed fittings.
    (5) Liquidtight flexible nonmetallic conduit with listed fittings.
    (6) Flexible cord listed for extra-hard usage and terminated
    with listed fittings. A conductor for use as an equipment
    grounding conductor shall be included in the flexible
    cord.
    (7) For elevator use, an identified elevator cable of Type
    EO, ETP, or ETT, shown under the “use” column in
    Table 400.4 for “hazardous (classified) locations” and
    terminated with listed fittings
    The panel is mounted on an I-beam frame. The panel is an Adalet instrument enclosure that is mounted just over 7' and at a 45° angle. (To allow the operator to read the numbers.) Rigid conduit is run from the equipment to within 18" of the control panel.

    So, I have two questions. First, are you permitted to run LMFC to a fixed in place control panel in a Class I, Div 2 location? Second, is there a code or standard that my journeyman was following, that is unknown to me?

    Thanks,
    Mark

  2. #2
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,718
    There may be other reasons beyond vibration that need flexibility but "must be made" is the operable phrase. Your description of the installation does not seem to meet that requirement. It's a judgment call if ease of installation may require it.

    Often overlooked is LFMC has some additional bonding/grounding issues in Section 501.30.

    As TC-ER(HL) is becoming a more recognized wiring method in Class I, Division 2, it may be added to the list in Section 501.10(B)(2) someday.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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