By Stanley Kaufman, CableSafe Inc.
The National Electrical Code is published by the National Fire Protection Association (NFPA; www.nfpa.org) with revisions on a three-year schedule. The 2011 NEC, which replaces the 2008 NEC, was released by NFPA in August 2010. There were many changes of interest to manufacturers, installers and users of communications cable and connectivity products.
This is the second in a series of nine articles, contributed on behalf of the Communications Cable and Connectivity Association (CCCA; www.cccassoc.org), concerning those relevant changes in the NEC. The initial article, published in July 2011, was an introduction to the NEC and its coverage of data-communications cables.
This article deals with the plethora of raceway types for data-communications cables and the beginning of a consolidation of these raceway types.
Definitions
The 2008 and 2011 NEC editions define raceway in Article 100, Definitions.
Raceway. An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables or busbars, with additional functions as permitted in this Code. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.
The 2008 NEC defines optical fiber raceway in Article 770.
Optical Fiber Raceway. A raceway designed for enclosing and routing listed optical fiber cables.
The definition is modified in the 2011 NEC.
Optical Fiber Raceway. An enclosed channel of nonmetallic materials designed for holding optical fiber cables in plenum, riser and general-purpose applications.
Communications raceway is not defined in the 2008 NEC. The definition in the 2011 NEC is as follows.
Communications Raceway. An enclosed channel of nonmetallic materials designed for holding communications wires and cables in plenum, riser, and general-purpose applications.
The NEC does not have a definition for signaling raceway or CATV raceway.
The key word in all the raceway definitions is "enclosed." Any cable support system that isn't enclosed, a cable tray for example, is not a raceway.
Raceway types and listing requirements
The 2008 NEC has four types of data-communications raceways—signaling, optical fiber, communications and CATV—each expressly listed for use with one family of data-communications cables. Each of these raceway types is available in plenum, riser and general-purpose grades. The listing, installation and applications for these raceways are covered by four articles.
- Article 725, Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits
- Article 770, Optical Fiber Cables and Raceways
- Article 800, Communications Circuits
- Article 820, Communications Antenna Television and Radio Distribution Systems
Article 760, Fire Alarm Systems, does not have its own raceway type.
The listing requirements for plenum, riser and general-purpose raceways are consistent with the listing requirements for plenum, riser and general-purpose cables, respectively.
These raceway families are redundant. The only difference, for example, between a plenum communications raceway and the other three plenum-grade raceways is marking. The 2011 NEC began the process of consolidating the types of data-communications raceways by eliminating CATV raceways and replacing them with communications raceways.
Applications in the 2008 NEC
The three main application areas for data-communications raceways are 1) air ducts and plenums, 2) risers, and 3) general-purpose spaces other than air ducts, plenums and risers.
General Purpose. As you would expect, optical fiber, communications and CATV general-purpose raceways are permitted to be installed in general-purpose space per the 2008 NEC. The types of cables permitted to be installed in these general-purpose data-communications raceways are restricted.
- Only optical-fiber cables are permitted to be installed in general-purpose optical fiber raceways.
- Only communications cables are permitted to be installed in general-purpose communications raceways.
- Only CATV cables are permitted to be installed in general-purpose CATV raceways.
The 2008 NEC does not specify any application for general-purpose signaling raceways other than supported by cable trays.
General-purpose signaling and communications raceways are explicitly permitted to be supported by cable trays. The cables installed in signaling raceways supported by cable trays are not restricted to Class 2, Class 3 cables; communications cables that are permitted to substitute for Class 2 and Class 3 cables are also permitted. Article 770 permits optical fiber cables to be supported by cable trays but makes no mention of optical fiber raceways being supported by cable trays. Likewise for Article 820 and CATV raceways.
Riser. Riser signaling, optical fiber, communications and CATV raceways are permitted to be installed in riser applications, i.e. in vertical runs in shaft from floor to floor, per the 2008 NEC. They are also permitted to substitute for their respective general-purpose raceways. The types of cables permitted to be installed in these riser data-communications raceways are restricted.
Plenum. Plenum signaling, optical fiber, communications and CATV raceways are permitted to be installed in plenum applications, i.e. "in other spaces used for environmental air," per the 2008 NEC. However the applications of plenum data-communications raceways are not consistent in the 2008 NEC, as plenum optical fiber, communications and CATV raceways are also permitted to be installed in air ducts.
As is the case for riser raceways, the types of cables permitted to be installed in these plenum data-communications raceways are restricted.
- Only plenum Class 2 and Class 3 cables are permitted to be installed in plenum signaling raceways.
- Only plenum optical fiber cables are permitted to be installed in plenum optical fiber raceways.
- Only plenum communications cables are permitted to be installed in plenum communications raceways.
- Only plenum CATV cables are permitted to be installed in plenum CATV raceways.
Plenum signaling, optical fiber, communications and CATV raceways are also permitted to substitute for their respective riser and general-purpose raceways.
Applications in the 2011 NEC
Signaling raceways. There were no changes to Article 725, dealing with signaling raceways, from the 2008 NEC to the 2011 NEC.
CATV raceways. As mentioned previously, CATV raceways were replaced by communications raceways in the 2011 NEC, thereby reducing the number of families of data-communications raceways from four to three.
No more air-duct applications. In the 2011 NEC, plenum optical fiber and plenum communications raceways are now prohibited from being installed in air ducts in order to correlate with NFPA 90A, Standard for the Installation of Air-Conditioning and Ventilation Systems. Plenum signaling raceways were not permitted in air ducts, so no change was required.
Raceway substitutions. The 2011 NEC permits communications raceways to be used in place of optical fiber raceways of equal or lower fire rating.
Permitting the use of communications raceways in place of optical fiber raceways reduces the types of raceways an installer has to carry to only two families of raceways: signaling and communications.
Removal of some restrictions. The restrictions that only communications cables are permitted to be installed in communications raceways and only optical fiber cables are permitted to be installed in optical fiber raceways have been eliminated. Furthermore, Article 820 explicitly permits CATV cables to be installed in communications raceways and Article 770 explicitly permits optical fiber cables to be installed in communications raceways. As mentioned earlier, there were no changes in the applications of signaling raceways; the restrictions on the types of cables permitted to be installed in these raceways remain in the 2011 NEC.
The 2014 NEC
Because communications raceways are already permitted to substitute for optical fiber raceways, optical fiber raceways are redundant. The next step in the consolidation of data-communications raceways may be the elimination of optical fiber raceways.
Permitting communications raceways to substitute for signaling raceways would also be a step toward complete consolidation of data-communications raceways. Ultimately communications raceways could be used for all data-communications applications.
The deadline for proposals for the 2014 NEC is November 4, 2011.
My next article will deal with data-communications cables in air ducts and plenums.
Author's disclaimer: This article, written on behalf of the Communications Cable and Connectivity Association (CCCA), is offered for general information and educational purposes. It is not offered, intended, nor should it be relied upon as legal advice. The article does not set forth the views of any member of any other party, nor may it be taken as such. CCCA makes no warranty regarding the accuracy of the information provided in this article, and expressly disclaims any implied warranties and any liability for use of the article or reliance on views expressed in it. CCCA does not endorse, approve or certify any information set forth in this article, nor does it guarantee the accuracy, completeness, efficacy, timeliness or correct sequencing of such information. Use of this article and the views expressed in it is voluntary, and reliance on it should only be undertaken after an independent review of its accuracy, completeness, efficacy and timeliness, and based on the individual facts and circumstances of a user.
Stanley Kaufman, Ph.D. is principal of CableSafe Inc. and a consultant to the Communications Cable and Connectivity Association (CCCA; www.cccassoc.org). His series of articles on the NEC will continue throughout the coming year.