FMC in Cable Tray

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publicgood

Senior Member
Location
WI, USA
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?
 

tom baker

First Chief Moderator
Staff member
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
 

publicgood

Senior Member
Location
WI, USA
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/wysiwyg/downloads/PDU Cables 2016 Brochure.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.
 

MasterTheNEC

Host of ElectricianLIVE.com
Location
McKinney, Texas
Occupation
Master Electrician & Director of Codes and Standards
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/wysiwyg/downloads/PDU Cables 2016 Brochure.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.
 
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