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Thread: FMC in Cable Tray

  1. #1
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    FMC in Cable Tray

    I see FMC is permitted in cable tray (392); however, 392 doesn't give guidance for spacing, fill or derate. I suppose this is because the qty of conductors is unknown. I'd hope to see criteria based on maximum fill maybe. Thoughts?

  2. #2
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    Can you post suggested language for a code proposal? When you say FMC, are you meaning AC or MC? I don't see many applications for FMC in CT. Anyway let us see a proposal
    Moderator-Washington State
    Ancora Imparo

  3. #3
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    By FMC I mean Flexible Metal Conduit (NEC 348). The specific application I find this in is beneath raised access floors in data centers. Although the cables may be placed directly on the floor, occasionally owners prefer to utilize cable tray for better organization of systems. Here is an example (image page 10 of 16):

    http://www.pducables.com/media/wysiw...20Brochure.pdf

    Thank you for entertaining my idea. Proposed language:

    392.10 (A) Wiring Methods. The wiring methods in Table 392.10(A) shall be permitted to be installed in cable tray systems under the conditions described in their respective articles and sections. WIRING METHODS CONSISTING OF CONDUIT OR TUBING SHALL FOLLOW THE SAME CONDITIONS AS MULTI-CONDUCTOR CABLES FOR THIS ARTICLE.

  4. #4
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    Quote Originally Posted by publicgood View Post
    By FMC I mean Flexible Metal Conduit (NEC 348). The specific application I find this in is beneath raised access floors in data centers. Although the cables may be placed directly on the floor, occasionally owners prefer to utilize cable tray for better organization of systems. Here is an example (image page 10 of 16):

    http://www.pducables.com/media/wysiw...20Brochure.pdf

    Thank you for entertaining my idea. Proposed language:

    392.10 (A) Wiring Methods. The wiring methods in Table 392.10(A) shall be permitted to be installed in cable tray systems under the conditions described in their respective articles and sections. WIRING METHODS CONSISTING OF CONDUIT OR TUBING SHALL FOLLOW THE SAME CONDITIONS AS MULTI-CONDUCTOR CABLES FOR THIS ARTICLE.
    Good luck with that one.....just a response from a code panel member....

    The fact that Section 392.10(A) actually does permit Type FMC in Cable Trays.......

    Does this not provide you the needed guidance?

    Part II. Installation
    392.10 Uses Permitted. Cable tray shall be permitted to be
    used as a support system for service conductors, feeders,
    branch circuits, communications circuits, control circuits, and
    signaling circuits. Cable tray installations shall not be limited to
    industrial establishments. Where exposed to direct rays of the
    sun, insulated conductors and jacketed cables shall be identified
    as being sunlight resistant. Cable trays and their associated
    fittings shall be identified for the intended use.


    (A) Wiring Methods. The wiring methods in Table 392.10(A)
    shall be permitted to be installed in cable tray systems under
    the conditions described in their respective articles and
    sections.

    Your next step would be to provide logical substantiation versus personal opinion. Please provide that substantiation in detail. Not being a critic here....just helping you increase your chances of a successful Public Input.
    Last edited by MasterTheNEC; 06-21-17 at 08:58 AM.
    *All code responses are based on the 2017 National Electrical Code[NEC]

  5. #5
    Join Date
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    I'm closing this thread. It isn't consistent with this forums rules.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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