This article was posted 03/16/2007 and is most likely outdated.

Article 320 Armored Cable: Type AC
 

 
Subject - Article 320 Armored Cable: Type AC

March 9, 2007  

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Armored Cable: Type AC

320.30 Secured and Supported

Part II. Installation

This section was reorganized with editorial changes to add clarity and uniform interpretation. New subsection (A) General, gives a title to the opening paragraph and includes requirements that apply generally. The requirements for securing and supporting have been separated into (B) and (C), as they are two different issues.
(A) General. Type AC cable must be supported and secured by staples, cable ties, straps, hangers, or similar fittings, designed and installed not to damage the cable.

(B) Securing. Type AC cable must be secured within 12 in. of every outlet box, junction box, cabinet, or fitting and at intervals not exceeding 4 1/2 ft where installed on or across framing members. Figure 320-1

Author’s Comment: Type AC cable is considered secured when installed horizontally through wooden or metal framing members [320.30(C)].

(C) Supporting. Type AC cable must be supported at intervals not exceeding 4 1/2 ft. Cables installed horizontally through wooden or metal framing members are considered secured and supported where such support doesn’t exceed 41/2 ft intervals. Figure 320-2

(D) Unsupported Cables. Type AC cable can be unsupported where the cable is:
(1) Fished through concealed spaces in finished buildings or structures, where support is impracticable; or
(2) Not more than 2 ft long at terminals where flexibility is necessary; or
(3) Not more than 6 ft long from the last point of cable support to the point of connection to a luminaire or other piece of electrical equipment within an accessible ceiling.

For the purposes of this section, Type AC cable fittings are permitted as a means of cable support.
Figure 320-3


Figure 320-1
(Click on image to enlarge)


Figure 320-2
(Click on image to enlarge)


Figure 320-3
(Click on image to enlarge)

   
 

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Comments
  • i have had several questions given to me in ref. to the use of gfci to supply a 120v 20ampere circuit receptacle and the way i saw the code the protection had to be at the origin of the circuit not at the end as some have told me , where they install a gf receptacle in the outlet box,

    please explain for us, thanks roger

    roger
    Reply to this comment

  • According to 645.(D)(2) Branch-circuit supply conductors installed in rigid metal conduit, PVC conduit, intermediate metal conduit, electrical metallic tubing, electrical nonmetallic tubing, metal wireway, nonmetallic wireway, surface metal raceway with metal cover, surface nonmetallic raceway, flexible metal conduit, liquidtight flexible metal conduit, liquidtight flexible nonmetallic conduit, MI cable, MC cable, or AC cable are permitted in the raised floor space.

    And the branch-circuit wiring methods must be securely fastened in place in accordance with 300.11.

    However, power, communications, connecting, and interconnecting cables part of listed information technology equipment aren’t required to be secured in place [645.5(E).

    Mike Holt
    Reply to this comment

  • Here is an informative presentation of difficulty implimenting of Article 645. http://www.bicsi.org/Content/Files/PDF/link2006/Stanitis.pdf

    Maintain
    Reply to this comment

  • Other than "Caddy-clip Bat wings" for #9 ceiling support wires, what else is a listed support for the same application ?

    Ed Beery
    Reply to this comment

  • Mike, I don't have the Building Code Books readily availible where I am currently located. I may be completly wrong in my posting, if so I apologize.

    I have had a little time to look at NEC Article 645. Here are some references located there as to room occupancy.

    645.4(4) The room is occupied only by those personnel needed for maintenace and functional operation of the installed information technology equipment. 645.4(5) The room is seperated from other occupancies by fire-resistant-rated walls, floors, and ceilings with protected openings. 645.4 FPN For futher information on room contruction requirements, see NFPA 75-2003 Chapter 5.

    Maintain
    Reply to this comment

  • I have had this argument with insectors for years. It is good to have it brought out in the open like this. I also liked the option of watching Mike tell us about it via the internet. Thanks Mike.

    ROBERT DEMOTT
    Reply to this comment

  • should have mentioned that it must be installed 1 1/4" back on the stud

    ragerman
    Reply to this comment

  • i use a lot of mc cable here at work. the cable is very easy to work with and gives me protection and a 20 amp feed for power

    chris taylor
    Reply to this comment

  • On a semi related issue, could you address cable support for a manufacture wiring system when applied beneath a 16" to 24" raised floor that occurs throughout an entire office building (not a server farm, co-location site, or data center). Code indicates that the cable shall be supported in same manner as required for product used in manufacture wiring system, which is mainly MC cable. MC cable can be routed through studs at 16" spacing or greater and be considered supported. Beneath a raised floor the manufacture wiring system is laying on a concrete deck. Some locations require the system to be strapped to the concrete at 6 foot intervals. What is your understanding of the code here? For Informational Technology Rooms Art. 645.5(E), power branch circuiting is not required to be secured under the raised floor. How and why is an office application different? To secure cables of a manufacture wiring system defeats the flexibility of the system.

    Brian Smith
    Reply to this comment

  • Since 320.30D allows: "fished through concealed spaces in finished buildings or structures, where support is impracticable;" providing a cut-in box, with AC fished to accessible ceiling is code compliant, right? Any additional requirements for this technique? -Jamie Fox

    Jamie Fox
    Reply to this comment


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