By Stanley Kaufman,
The National Electrical Code® (NEC®) is published by the National Fire Protection Association (NFPA) with the revisions on a three-year schedule. The 2020 NEC, which replaces the 2017 NEC, was issued by the NFPA in August, 2019.
This article, contributed on behalf of the Communications Cable and Connectivity Association (CCCA), is intended to provide the reader with a guide to the key changes in the 2020 National Electrical Code that are of interest to manufacturers, installers, distributors and users of data/comm cables.
Although widely used in the industry, the term data/comm cables does not appear in the NEC. The term data/comm cable, as used in this article, encompasses six families of cable types in the NEC.
- Optical fiber cables, Type OFNP, OFCP, OFNR, OFCR, OFNG, OFCG, OFN and OFC
- Communications cables, Types CMP, CMR, CMG and CM
- Coaxial cable TV cables, Types CATVP, CATVR and CATV
- Class 2 cables, Types CL2P, CL2R and CL2
- Class 3 cables, Types CL3P, CL3R and CL3
- Power-limited fire alarm cables, Types FPLP, FPLR and FPL
The applications of data/comm cables and their associated equipment are in 13 articles that are the responsibility of three code-making panels.
Creation of new Article 800
The most important and most obvious change is that Chapter 8 has a new general article. Just like Chapter 3, Wiring Methods and Materials, has a general article, Article 300, General Requirements for Wiring Methods and Materials, Chapter 8, Communications Systems, now has a general article, Article 800, General Requirements for Communications Systems. The primary purpose of the new article is to consolidate redundant requirements by placing them into one general article.
The following are examples of interest to manufacturers, installers, distributors and users of data/comm cables.
- Listing requirements for plenum, riser, general-purpose and limited-use, communications, cable TV and network-powered broadband communications cables have been removed from Article 805 (formerly Article 800), Article 820, and Article 830 and placed in the new Article 800 in order to reduce the redundancy in cable listing requirements in Chapter 8. Listing requirements for other than plenum, riser, general-purpose and limited-use cables, such as undercarpet cables, communications wires and drop wire were not moved.
- Listing requirements for cable routing assemblies and communications raceways have been moved from Article 805 to the new general article (Article 800) because the applications of cable routing assemblies and communications raceways are in multiple articles and chapters.
- Applications of listed communications wires and cables, listed cable TV coaxial cables, and listed network-powered communications cables have been removed from Article 805 (formerly Article 800), Article 820, and Article 830 and placed in the new Article 800.
- Definitions of terms used in multiple articles in Chapter 8 have been moved to the new general article (Article 800). Definitions used in multiple articles (other than just Chapter 8) have been moved to the definitions section in Chapter 1.
- Many of the installation requirements for data/comm cables have been consolidated to new Article 800, including the following.
- 800.21 Access to Electrical Equipment Behind Panels Designed to Allow Access
- 800.24 Mechanical Execution of Work
- 800.25 Abandoned Cables
- 800.26 Spread of Fire or Products of Combustion
- 800.27 Temperature Limitation of Wires and Cables—Note that the requirement in Section 800.27 is simplified. The new text states, “No wire or cable shall be used in such a manner that its operating temperature exceeds that of its rating.” Section 800.3(H) of the 2017 NEC has been deleted; it referred to Section 310.15(A)(3), which is considerably more complicated.
- 800.44 Overhead (Aerial) Wires and Cables
- 800.49 Metal Entrance Conduit Grounding
- 800.53 Separation from Lightning Conductors
Powering over data/comm cables
Using data/comm cables for providing power in addition to communicating/signaling has been a hot topic in the data/comm industry. The 2017 NEC was the first edition of the NEC to address this issue, which includes, but is not limited to, Power over Ethernet (PoE).
In the 2017 NEC, Section 840.160 permits communications cables to carry circuits for powering communications equipment in addition to the communications signal, provided that the power supplied doesn’t exceed 60 watts. Above 60 watts, Section 840.160 defers to the requirements in Section 725.144 of Article 725, Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits.
In the 2020 NEC, Section 840.160 has been modified to clarify that:
The communications cables must be listed communications cable with the listing in accordance with Section 805.179;
The communications equipment must be listed communications equipment with the listing in accordance with Section 805.170;
The power source must be listed in accordance with Section 840.170(G);
Listed 4-pair communications cables are permitted to substitute for Class 2 and Class 3 cables installed in accordance with Section 725.144 and with the cable substitution requirements Section 725.154(A).
In the 2017 and 2020 NEC, Section 725.144 has two alternate provisions for assuring that the cables carrying power and signaling do not exceed their temperature rating. The first option is to comply with the ampacity table, Table 725.144. The other option is to use “Limited Power” (-LP) cables and to keep the current in each conductor below the ampere limit marked on the cable. The listing requirements for Limited Power (LP) Cables are in Section 725.179(I) in the 2017 NEC.
In the 2020 NEC, the ampacity table in Section 725.144, which is based on an Underwriters Laboratories fact-finding study, has been modified to use true rounding instead of rounding down. In some instances this results in slightly higher ampacities being permitted.
There are new marking requirements in Section 725.121(C) of the 2020 NEC for power supplies that are used to supply power to cables that simultaneously transmit power and signal/communicate. These new marking requirements facilitate matching the ampacities of the cables with the output current of the power supply. The ampacity of the cables, or the current rating in the case of an -LP cable, must be equal to or exceed the current rating of the power supply.
In the 2017 NEC, Section 725.121(C), which covers marking requirements for limited power circuits, requires a label indicating the maximum voltage and current output for each connection point.
The text of Section 725.121(C) in the 2020 NEC states:
“(C) Marking. The power sources for limited power circuits in 725.121(A)(3), limited power circuits for listed audio/video equipment, listed information technology equipment, listed communications equipment, and listed industrial equipment in 725.121(A)(4) shall have a label indicating the maximum voltage and rated current output per conductor for each connection point on the power source. Where multiple connection points have the same rating, a single label shall be permitted to be used. For equipment with a rated current per conductor less than 0.3 amperes, the effective date shall be January 1, 2021.
Information Note No. 1: Rated Current for power sources covered in 725.144 is the output current per conductor the power source is designed to deliver to an operational load at normal operating conditions, as declared by the manufacturer.
Information Note No. 2: An example of a label is ‘52V @ 0.433A, 56V MAX’ for an IEEE 802.3 compliant Class 8 power source.”
Local area network (LAN) cables are now nearly universally used for PoE applications. Listed 4-pair communications cables are almost always used in place of listed 4-pair Class 2 or Class 3 cables as permitted by the Cable Substitutions Table 725.154(A). 2020 NEC Section 805.179(D) has new provisions that recognize the listing of communications Limited Power (LP) cables for these applications.
The installation of Class 2 and Class 3 circuits in communications cables is covered in 2017 NEC Sections 725.139(D)(1) and 800.133(A)(b).
“(1) Classified as Communications Circuits. Class 2 and Class 3 circuit conductors shall be permitted in the same cable with communications circuits, in which case the Class 2 and Class 3 circuits shall be classified as communications circuits and shall be installed in accordance with the requirements of Article 800. The cables shall be listed as communications cables.”
“(b) Class 2 and Class 3 Circuits. Class 1 circuits shall not be run in the same cable with communications circuits. Class 2 and Class 3 circuit conductors shall be permitted in the same cable with communications circuits, in which case the Class 2 and Class 3 circuits shall be classified as communications circuits and shall meet the requirements of this article. The cables shall be listed as communications cables.”
The requirement that the Class 2 and Class 3 circuits be classified as communications circuits conflicts with the requirement in Section 840.160 that communications circuits above 60 watts be installed in accordance with Section 725.144. That conflict has been removed in the 2020 Code.
Sections 725.139(D)(1) and 805.133(A)(b) in 2020 NEC deleted the requirements that the Class 2 or Class 3 circuits be classified as communications circuits.
“(1) Communications Cables. Conductors of one or more Class 2 and Class 3 circuits shall be permitted in the same cable with conductors of communications circuits provided that the cable is a listed communications cable that shall be installed in accordance with the requirements of Part V of Article 805. The cables shall be listed as communications cables.”
“(b) Class 2 and Class 3 Circuits. Class 1 circuits shall not be run in the same cable with communications circuits. Class 2 and Class 3 circuit conductors shall be permitted in the same listed communications cable with communications circuits.”
Grounding of green wires
Section 250.119 of the 2017 NEC has a long-standing requirement that identifies the green wires in a cable as ground wires. This was obviously written with power cables in mind. There is an exception for communications, Class 2, Class 3 and power-limited fire alarm cables operating at less than 50 volts. That exception is clearly inadequate because many communications, Class 2, Class 3 and power-limited fire alarm circuits operate above 50 volts.
In the 2020 NEC, the 50 volt exception in 250.119 has been changed to be 50 volts AC or 60 volts DC in order to accommodate PoE. Recognizing 60 volt DC circuits is a step in the right direction but still inadequate because it does not encompass all Class 2, Class 3 circuits permitted in Tables 11(A), 11(B) in Chapter 9, and all power-limited fire alarm circuits permitted by Tables 12(A) and 12(B) in Chapter 9.
In the 2020 NEC, the new Section 725.3(P) for Class 2 and Class 3 cables, and new Section 760.3(O) for power-limited fire alarm cables, permit green wires to be used ungrounded without the voltage limitations in Section 250.119.
Code Organization, Section 90.3 permits Chapters 5 through 7 to supplement or modify the requirements of Chapters 1 through 7; consequently, the requirements of 725.3(P) and 760.3(O) override the requirements of Section 250.119. Section 90.3 also exempts Chapter 8 from the requirements of Chapters 1 through 7 unless specifically referenced in Chapter 8. Consequently, Section 250.119 does not apply to communications circuits because that section is not referenced in Chapter 8.
Data center cabling
Article 645, Information Technology Equipment, covers the installation of information technology equipment in an information technology equipment room, i.e. a data center. Article 645 is written to correlate with the fire protection requirements in NFPA 75, Standard for the Fire Protection of Information Technology Equipment. Prior to the 2017 edition, NFPA 75 always required active fire protection, typically sprinklers or a gaseous clean agent, in the raised floor plenum under the data center. The 2017 edition of NFPA 75 permits two alternate approaches to fire protection in the raised floor plenum: either provide active fire protection or only use plenum grade materials, which include, of course, plenum cable.
In the 2020 NEC, Section 645.5(E) correlates with NFPA 75-2017 by requiring plenum cables where cables are exposed to the airflow (not in conduit) in the area under the raised floor and that area is not protected by active fire suppression. Where active fire suppression is present, all cable types, except limited-use (CMX and CATVX), are permitted under the raised floor.
The NEC has always permitted marking on communications cables to indicate additional attributes beyond those required by the Code, for example, a LAN cable marked CAT 6A. The 2020 NEC now explicitly permits optional cable markings. Sections 725.179(K) and 805.179(G) state that, “Cables shall be permitted to be surface marked to indicate special characteristics of the cable materials.” Information notes provide examples of optional markings.
Painting of cables
In the construction of office buildings, cables are often installed before construction is completed. Consequently, communications cables may be inadvertently spray-painted or coated with foreign substances. Painting the cables can change the cable performance properties in unknown ways. This is especially true of plenum cables, which are designed to have excellent fire-resistance properties. Painting or coating of plenum cables might compromise their fire-safety properties.
In order to alert users to this issue, the 2017 NEC added Informational Notes to Articles 770 (optical fiber cables), 800 (communications cables) and 820 (CATV coaxial cables). In the 2020 NEC, Informational Notes were added to Sections 725.24 and 760.24. These notes state, respectively, “Paint, plaster, cleaners, abrasives, corrosive residues, or other contaminants may result in an undetermined alteration of Class 1, Class 2, Class 3 and PLTC cable properties,” and, “Paint, plaster, cleaners, abrasives, corrosive residues, or other contaminants may result in an undetermined alteration of PLFA and NPLFA cable properties.”
Author’s notes: NFPA 70, NFPA, National Fire Protection Association, National Electrical Code, and NEC are registered trademarks of the National Fire Protection Association.
This paper, provided by the Communications Cable and Connectivity Association, is offered for general information and educational purposes. It is not offered, intended, nor should it be relied upon as legal advice. The paper does not set forth the views of any member or any other party, nor may it be taken as such. CCCA makes no warranty regarding the accuracy of the information provided in this paper, and expressly disclaims any implied warranties and any liability for use of the paper or reliance on views expressed in it. CCCA does not endorse, approve, or certify any information set forth in this paper, nor does it guarantee the accuracy, completeness, efficacy, timeliness, or correct sequencing of such information. Use of the paper 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). He is a member of NEC Code-making Panels 12 and 16. He is also a member of the NFPA Technical Committee on Electronic Computer Systems, which is responsible for NFPA 75, Standard for the Fire Protection of Information Technology Equipment and the NFPA Technical Committee on Telecommunications, which is responsible for NFPA 76, Standard for the Fire Protection of Telecommunications Facilities.