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    NM as flex cord

    NM as flex cord

    New postby Marc M on Fri Aug 30, 2013 5:19 pm

    Hey Jerry, is there a code that actually states NM cant be used as a flexible cord? I didn't see anything.
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    Re: NM as flex cord

    New postby Jerry Peck - Codeman on Fri Aug 30, 2013 8:29 pm

    Marc,

    NM is not suitable for use as a flexible cord as it is not a type listed in 400.4 and Table 400.4:
    - From the 2008 NEC:
    - - 400.4 Types.
    - - - 400.4 Types.
    - - - - Flexible cords and flexible cables shall conform to the description in Table 400.4. Types of flexible cords and flexible cables other than those listed in the table shall be the subject of special investigation.
    - - Table 400.4 Flexible Cords and Cables (See 400.4.)
    - - - (Table 400.4 lists the approved types of flexible cords, NM cable is not listed in this table and is thus not a flexible cord.)

    That said, though, depending on how they are using it they may just need to provide protection from physical damage as it may not actually be being used as a "flexible cord".

    Any additional information on what it is being used for and how it is being used?
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    Re: NM as flex cord

    New postby Marc M on Fri Aug 30, 2013 11:26 pm

    It was used as a permanent source of power for an FAU.
    So is it safe to say that through process of elimination, and because its not listed..., therefore its not approved?
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    Re: NM as flex cord

    New postby Jerry Peck - Codeman on Fri Aug 30, 2013 11:57 pm

    Unless the FAU is vibrating and shaking so much that it needs a flexible cord for connection (in which case there would be major problems with the FAU), NM cable may be used to connect the FAU to the disconnect or junction box.

    The concern I have is protection of the NM cable from physical damage, while there may be some locations in which the FAU is installed that the NM cable may not require protection from physical damage, I suspect that those locations are few and far between and that the NM cable in the installation you are looking at probably requires protection from physical damage.

    Typically, flexible metal conduit is used for that protection and is installed between the FAU and the disconnect or junction box. Of course, though, when they install the flexible metal conduit they might as well replace the NM cable with separate conductors, and while replacing the NM cable with separate conductors they might as well use stranded conductors instead of solid conductors.

    They also need to verify the temperature rating of the insulation as the FAU may specify 90°C rated insulation (which NM cable has had since NMB replaced NM in the late 1980s).

    Another consideration may be the terminals as the terminals may be rated only for stranded conductors (that would be on the label inside the electrical compartment with other information related to the terminals, wire sizing, temperature rating, etc.).
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    Re: NM as flex cord

    New postby Jerry Peck - Codeman on Sat Aug 31, 2013 11:52 am

    Marc,

    I forgot to add this: if I found flexible cord used to connect to a FAU I would look hard for a reason for the flexible cord to have been used as there likely is not a suitable reason for using flexible cord to connect to a FAU ... finding flexible cord would be a red flag to me.

    And if a cord and plug was used for the FAU, then there is no cord and plug set approved for that use and the plug would be a problem as it would likely not be rated for that use - but I would need to know more about the FAU to determine that for sure.

    The reason is this:
    From the 2008 NEC (bold and underlining are mine)
    - ARTICLE 400 Flexible Cords and Cables
    - - 400.7 Uses Permitted.
    - - - (A) Uses. Flexible cords and cables shall be used only for the following:
    - - - - (1) Pendants
    - - - - (2) Wiring of luminaires
    - - - - (3) Connection of portable luminaires, portable and mobile signs, or appliances
    - - - - (4) Elevator cables
    - - - - (5) Wiring of cranes and hoists
    - - - - (6) Connection of utilization equipment to facilitate frequent interchange
    - - - - (7) Prevention of the transmission of noise or vibration
    - - - - (8) Appliances where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance and repair, and the appliance is intended or identified for flexible cord connection
    - - - - (9) Connection of moving parts
    - - - - (10) Where specifically permitted elsewhere in this Code
    - - - (B) Attachment Plugs. Where used as permitted in 400.7(A)(3), (A)(6), and (A)(8), each flexible cord shall be equipped with an attachment plug and shall be energized from a receptacle outlet.
    - - - - Exception: As permitted in 368.56.
    - - - 400.8 Uses Not Permitted.
    - - - - Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:
    - - - - - (1) As a substitute for the fixed wiring of a structure
    - - - - - (2) Where run through holes in walls, structural ceilings, suspended ceilings, dropped ceilings, or floors
    - - - - - (3) Where run through doorways, windows, or similar openings
    - - - - - (4) Where attached to building surfaces
    - - - - - - Exception to (4): Flexible cord and cable shall be permitted to be attached to building surfaces in accordance with the provisions of 368.56(B)
    - - - - - (5) Where concealed by walls, floors, or ceilings or located above suspended or dropped ceilings
    - - - - - (6) Where installed in raceways, except as otherwise permitted in this Code
    - - - - - (7) Where subject to physical damage

    I suspect it will be difficult to find an FAU installation which meets 400.7(8) and for which 400.8(1) could be applied. A food waste grinder would meet those restrictions as garage disposers are designed to meet "fastening means and mechanical connections are specifically designed to permit ready removal", so a cord and plug could be used there as that would also meet 400.7(B) allowing the plug to be used.

    "(B) Attachment Plugs. Where used as permitted in 400.7(A)(3), (A)(6), and (A)(8), each flexible cord shall be equipped with an attachment plug and shall be energized from a receptacle outlet."

    When 400.7(A)(8) is used ... and attachment plug "shall" be used and plugged into a "receptacle outlet" - except as allowed by 368.56 (which is not applicable here):
    - ARTICLE 368 Busways
    - - 368.56 Branches from Busways.
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