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Thread: MC cable

  1. #1
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    MC cable

    Interlocking Metal Clad Cable is a flexible cable but is permitted to be used when 'flexibility' is necessary? The NEC 2011 shows nothing about this. If yes, which length ?

  2. #2
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    I think depending on the application an inspector could very well say no based on 330.12(1) even if you complied with 330.30 Securing and Supporting requirements.


    330.12 Uses Not Permitted. Type MC cable shall not be
    used under either of the following conditions:
    (1) Where subject to physical damage

  3. #3
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    It depends on the application. I think length wise, you would follow the same rule for flex or sealtite.
    The Man Prayer: I am a man ... I can change ... If I have to ... I guess.

  4. #4
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    But AC is only 2ft when 'flexibility is necessary"........

  5. #5
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    Must be a trick question because I can't find anything pertaining to when flexability is necessary in the MC section.

    Since AC and MC are similar in consruction, I would say 2 feet is your answer.

    Edit: OTOH because it is not specified, you may be able to go with the maximum unsupported length, which is 6 feet. (330.30 (D)(2))

    Is this an exam question you have encountered?
    Last edited by Stevareno; 10-14-12 at 11:13 PM.
    The Man Prayer: I am a man ... I can change ... If I have to ... I guess.

  6. #6
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    Yes, it is an exam question and Yes I can't find anything pertaining to that issue. That is the problem. And the answers were True or False....
    Thanks, Stevareno

  7. #7
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    Quote Originally Posted by CelsoSr View Post
    Yes, it is an exam question and Yes I can't find anything pertaining to that issue. That is the problem. And the answers were True or False....
    Thanks, Stevareno
    True' take a look at (D) 2



    320.30 Securing and Supporting.
    (A) General. Type AC cable shall be supported and secured by staples, cable ties, straps, hangers, or similar fittings, designed and installed so as not to damage the cable.
    (B) Securing. Unless otherwise permitted, Type AC cable shall be secured within 300 mm (12 in.) of every outlet box, junction box, cabinet, or fitting and at intervals not exceeding 1.4 m (4½ ft) where installed on or across framing members.
    (C) Supporting. Unless otherwise permitted, Type AC cable shall be supported at intervals not exceeding 1.4 m (4½ ft).
    Horizontal runs of Type AC cable installed in wooden or metal framing members or similar supporting means shall be considered supported where such support does not exceed 1.4-m (4½-ft) intervals.
    (D) Unsupported Cables. Type AC cable shall be permitted to be unsupported where the cable complies with any of the following:

    1. Is fished between access points through concealed spaces in finished buildings or structures and supporting is impracticable
    2. Is not more than 600 mm (2 ft) in length at terminals where flexibility is necessary
    3. Is not more than 1.8 m (6 ft) in length from the last point of cable support to the point of connection to a luminaire(s) or other electrical equipment and the cable and point of connection are within an accessible ceiling. For the purposes of this section, Type AC cable fittings shall be permitted as a means of cable support.

  8. #8
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    Gregg: My original question was about MC cable, can be used when 'flexibility is necessary'? To feed a motor or other equipment that vibrate ? If yes, what length ? AC 320-Article clearly specify: 2 ft, but MC-330 Article says nothing when 'flexibility is needed'. The Code <br>is very specific where flexibility is necessary in other flexible&nbsp;wiring methods, but not about MC. That is why my question is. Maybe I should ask to&nbsp;a manufacturer.&nbsp;&nbsp; &nbsp;<br>Thanks a lot for your time...

  9. #9
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    In my opinion there is no direct NEC answer.

    Run MC to a vibrating motor? Sure.

    Run MC to power a device on a door that opens and closes 50 times a day? Not so much.

    I feel it would come down to the inspectors feeling of the potential for physical damage.

  10. #10
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    Thanks iwire, I appreciate you point of view, and I feel too that the inspector will be who decides.....
    I made the question to Southwire the manufacturer....

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