TEK Brief July Is there a difference in installation requirements between communications cables with and without the LP designation?

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1 BECAUSE YOUR BUSINESS RUNS THROUGH US TEK Brief July 2016 LP Cabling: Frequently Asked Questions Table of Contents Introduction Prior to the beginning of the review cycle of the 2017 National Electrical Code (NEC), there was some concern Overview... 1 regarding temperature rise in large bundles of 23 AWG or 24 AWG twisted-pair data communications cables UL and the National Electrical Code (NEC)... 2 due to heat produced while carrying low voltage LP Cables: What does it mean exactly?... 2 direct current (DC). The NEC generally focuses on higher voltage, larger AWG cables used in construction Berk-Tek s position on LP marked cabling... 5 projects, in order to minimize the risk of electric shock and fire. The requirements for communications systems and associated cabling are governed exclusively by Chapter 8 within the NEC. Currently, the NEC is worded in such a way that it permits up to 100 watts per circuit to be carried over communications cables. Each pair in a four (4) pair data communications cable could be considered a circuit; thereby technically allowing up to 400 watts of power over communications cables. Combine this with the fact that the IEEE is now developing 802.3bt, which is the 3rd generation of Power over Ethernet (PoE) and will allow more than 3X the power levels that the second generation of PoE allowed (30W to now almost 100W) through communications cabling. The trend is clear; powering more devices using communications cabling is coming. The question becomes: What are the limitations from heat generation due to power deployment, especially in large cable bundles? Introduction... 1 To address these concerns, an effort was undertaken by Underwriters Laboratories (UL) to define a new cable marking of Limited Power (-LP) for communications cable. The LP cable designation indicates that the cable has been evaluated by UL to carry the marked current in any reasonable worst-case installation without exceeding the temperature rating of the cable. This document addresses Frequently Asked Questions relevant to the recent and expected developments of these efforts. Overview Are Limited Power (LP) marked cables new to the industry? Yes, communications cables with the optional Limited Power (LP) marking are new to the industry as of September The LP cable marking is not only new, but it is also an entirely optional cable designation for communications cables. The LP cable marking indicates that the cable has been evaluated by UL to carry the marked current in any reasonable worst-case installation without exceeding the temperature rating of the cable. Is there a difference in installation requirements between communications cables with and without the LP designation? There is no difference between the installation of standard communications cable and LP marked cable. Is PoE code compliant? The IEEE and the industry have gone to great measures to assure that the PoE standards are code compliant and provide a safe

2 Page 2 method to supply power to remote Ethernet devices such as cameras, lighting, building automation and access points. As always, you should check to make sure that all cables and equipment are properly listed, marked and labeled as suitable for the intended purpose. Will my existing cabling support power distribution? It is expected that common, pre-existing cables will be deemed suitable for applications that require up to 60 watts, covering all IEEE 802.3af and 802.3at applications. Berk-Tek s Category 6 and 6A cables, which are listed to 75 C (with some premium offerings listed to 90 C), are suitable for up to 100W, which will be included in the IEEE 802.3bt standard that is expected by UL and the National Electrical Code (NEC) Who sets the standards for LP marked cables? UL released a Certification Requirements Decision (CRD) containing their interpretation of the requirements for listed communications cables to carry the optional LP marking based upon a fact-finding study they conducted in This CRD represents only the view of UL and is not part of any ANSI standard. Concurrently, UL has initiated a proposed revision to UL 444, the standard for communications cable and is seeking industry comment on the LP cable certification requirements. The NFPA is in the process of completing the 2017 revision of NFPA 70, commonly known as the National Electrical Code (NEC) and is expected to publish the next edition in August Does the NEC require the use of LP marked cables? No. There are no current or proposed requirements to require LP marked cables to be installed. Article 840 (Premisespowered Broadband Communications Systems) in the forthcoming 2017 edition of the NEC states that power distribution at or below 60 watts does not require any special consideration. However, for power levels above 60W, Article 840 references Article 725 which provides guidance on limiting current and bundle size (although the NEC never defines bundle ) through proper conductor size (AWG) (See Table located on page 4 of this document). Please note that the optional LP Designation is not in Article 800 which governs Communication Circuits (LAN cabling and Connectivity). Could optional LP markings become required? There are no current or proposed plans to require LP marking within the NEC. It is intended to be an optional marking. A significant amount of opposition still exists from many different industry organizations, including IEEE, Ethernet Alliance, BICSI, and others. Additional industry studies are needed to generate a more specific set of operational parameters and requirements for LP marking to achieve industry consensus. Additionally, immediate adoption of the latest version of the NEC is not mandatory and varies by individual states. How can the Authority Having Jurisdiction (AHJ) enforce the optional LP cable marking? Since the LP cable marking is entirely optional, and not included in Article 800, it would be very unlikely for AHJ to require its use.

3 Page 3 Limited Power Cables (LP): What does it mean exactly? How are Limited Power (LP) marked cables tested and measured? First, a homogeneous cable bundle of 192 cables is built and placed in six feet of non-metallic conduit, and each end of the conduit is filled with insulation to minimize air movement (Figure 1). An electric current is then applied to each conductor between 0.5 amps and 1.0 amp, in 0.1 amp increments. For example, if testing for LP 0.5, then 0.5 amps (100 W) is applied to each conductor in the 192-cable bundle. A temperature probe is placed in the middle of the bundle and on the jacket of the center-most cable to take the worst-case temperature reading Figure 1: LP Testing after maximum sustained temperature is reached. There are six (6) LP markings for data communications cabling (see Table 1 on page 4). Language taken directly from the draft UL , and is below for reference as well. Please note that the cable bundle is homogeneous. The LP marking does not take into consideration the circumstance where some cables are LP listed and others are not, and the others may have lower temperature ratings and smaller AWG sizes. Per the June 2016 draft of UL , Limited Power (LP) cabling is tested as such: The cables shall be arranged in a bundle consisting of 192 cables and electrically connected in series to a power supply capable of providing the rated current marked as part of the LP rating. The inner 37 cables shall be arranged in a hexagonal densest packing structure which represents the worst case thermal dissipation situation. The remaining cables shall be evenly distributed in a random fashion to form a 192-cable bundle. The bundle shall be placed in a 1.83 m ± 5 cm (6 foot ± 2 in) long commercially available non-metallic conduit (Schedule 40) with the minimum diameter needed to install the bundle without putting pressure on the cables. Each end of the conduit shall be filled with insulation. Per the June 2016 draft of UL 444, , Limited Power (LP) cabling is measured as such: The temperatures shall be measured on the outer jacket and conductor insulation of the center cable at the midpoint of the cable. In addition, temperatures shall be measured on the jacket and conductor insulation on the center cable 0.6 m (2 ft) on each side of center thermocouple. What are the optional LP marking requirements and what do they mean? The requirements for the optional LP markings are based on three (3) criteria. They are: 1. The cables maximum rated temperature listing (e.g., 60 C, 75 C, or 90 C) 2. The amount of electric direct current applied to each conductor (0.5 amps to 1.0 amps in 0.1 amp increments) 3. The temperature rise in the center of a 192-cable bundle associated with the electric current applied. The three requirements lead to this equation: Temperature rise from electric current applied 45 C (assumed maximum ambient temperature of operating environment) + Cables maximum rated temperature listing An example: Cable under test had 0.5 amps per conductor applied (100 W assuming 50 volts). The temperature rise at the center of the bundle was determined to be 20 C. The cables maximum rated temperature listing is 75 C. Therefore, the calculation would be: 20 C + 45 C 75 C. Since 65 C < 75 C, the cable meets the requirement for LP 0.5. The cable could then be tested for LP 0.6 by increasing the current to 0.6 amps per conductor and after maximum sustained temperature rise is attained, repeat the calculation. Please see Table 1 for the six (6) optional LP markings for communications cabling.

4 Page 4 Table 1: Optional LP Markings LP Listing Maximum Amount of Power LP (0.5A) 0.5 amp per conductor (100 W) LP (0.6A) 0.6 amp per conductor (120 W) LP (0.7A) 0.7 amp per conductor (140 W) LP (0.8A) 0.8 amp per conductor (160 W) LP (0.9A) 0.9 amp per conductor (180 W) LP (1.0A) 1.0 amp per conductor (200 W) Why are there so many levels of the optional LP marked cable? The original intent was to define a single LP listed cable listing that would allow the maximum 400 W deployment on communications cabling. However, it quickly became apparent that such a cable would be cost prohibitive, and may not fit within the connectivity, so multiple ratings were proposed to allow for cost-effective, innovative solutions to be developed. With the exception of LP 0.5 (0.5 amps per conductor or 100 watts), these classifications fall above all current and proposed maximum power deployment systems. How do I read Table that is in the draft NEC (2017) Article 725 and referenced by Article 840? The table in the Article 725 of the 2017 NEC is derived from a UL fact-finding study conducted in 2015 and applies to fourpair, class 2 and class 3 power-limited circuits that transmit power and data to a powered device, regardless if the cable has the optional UL LP marking or not. For example, the chart illustrates that in a homogeneous bundle of 192 cables, it would be considered allowable to transmit up to 0.5 amps through each conductor (100W) of a 75 C listed cable constructed with 23 AWG conductors. UL conducted the testing and based their results with an assumed 45 C maximum ambient temperature. The NEC, however, uses 30 C as their maximum ambient temperature. Therefore the UL marking, which based qualification upon a 45 C ambient temperature is more stringent for a given current due to having 15 C less temperature budget. Please see Note 1 at the bottom of the chart, which states, For bundle sizes over 192 cables, or for conductor sizes smaller than 26 AWG, ampacities shall be permitted to be determined by qualified personnel under engineering supervision. Table , Ampacities of each conductor (in Amperes) in a 4-pair Class 2 or Class 3 data cable, based on copper conductors at ambient temperature of 30 C (86 F) with all conductors in all cables carrying current, 60 C (140 F) and 90 C (194 F) rated cables Number of 4-pair cables in a bundle AWG Temperature Rating Temperature Rating Temperature Rating Temperature Rating Temperature Rating Temperature Rating Temperature Rating 60 C 75 C 90 C 60 C 75 C 90 C 60 C 75 C 90 C 60 C 75 C 90 C 60 C 75 C 90 C 60 C 75 C 90 C 60 C 75 C 90 C N/A N/A N/A Note 1: For bundle sizes over 192 cables, or for conductor sizes smaller than 26 AWG, ampacities shall be permitted to be determined by qualified personnel under engineering supervision. Note 2: Where only half of the conductors in each cable are carrying current, the values in the table shall be permitted to be increased by a factor of 1.4. Informational Note: The conductor sizes in data cables in widespread use are typically AWG. The engineers at the TEK Center at Berk-Tek have already thoroughly tested and certified that the following products are capable of supporting 100 W of power safely. This is the maximum amount of power that the PoE standard (IEEE 802.3bt) currently under development will allow. The products* are: LANmark TM -XTP and LANmark TM -10G FTP LANmark TM -10G2 LANmark TM LANmark TM LANmark TM -6 *All products listed are capable of safely supporting >192 cable 100 W of PoE. Call BERK-TEK for more information.

5 Page 5 Berk-Tek s position on LP marked cables What is Berk-Tek s involvement with developing an LP marking? The TEK Center at Berk-Tek has performed many studies and invested thousands of hours into determining the impact of power distribution and its associated temperature rise within cable bundles. The TEK Center has tested cable bundles of various sizes as well as cable bundles in cable tray, conduit, and other installation environments (see example in Figure 2). UL and others have witnessed our testing, and we have provided our results to both UL and the standards bodies in an effort to support the safe deployment of higher power deployment systems. Berk-Tek continues to invest in testing, and the results of our ongoing testing will be provided to the industry. What is Berk-Tek s recommendation regarding the optional LP marking? Berk-Tek does not believe the optional LP marking adequately addresses the issues with power delivery over communications cables for the following reasons: 1. True safety measures are required listings, not optional designations. 2. The LP designation does not include connectors, patch cords or patch panels. 3. The LP designation is only for homogeneous bundles (no mixed cables, tray, J-hooks, etc.) 4. The burden of safety is on the user, not the system (no circuit breakers or fuses) Figure 2: PoE Testing at the TEK Center 5. The NEC allows the TEK Center s Certificate of Authority to certify the maximum current and bundle size for our customers regardless of the optional LP designation. I understand that LP is an optional designation appended to a safety listing, but what happens to my data? Exactly! This is exactly why Berk-Tek has also used the results of our testing over the last several years to make improvements to our cable designs and manufacturing processes. To illustrate the performance difference with various types of cabling, Berk-Tek developed the Converged Application Score (or CA Score). The CA Score is an indicator of how well IP traffic is protected and how much temperature rise there is when the cable undergoes PoE testing. The score is represented by a numeric value between 1 and 10, with 1 being the worst and 10 being the best (see Figure 3). A higher score means that there were fewer flaws noticed in our application testing of VoIP, Data, and IP Video. Also, a higher score indicates that the cable experienced less heat rise while supplying 100 W of power in a large bundle. More information on Berk-Tek s CA Score can be found here >> Tell me more about the CA Score Figure 3: CA Score graphic illustrating different levels of performance. This stamp certifies that all testing was performed, reviewed, and approved by highly trained, experienced engineers dedicated to studying and developing solutions for future network infrastructures. Located in New Holland, Pennsylvania, The TEK Center at Berk-Tek is comprised of several labs and a technology showcase. By employing industry-leading research, advanced testing procedures, and sophisticated modeling for emerging technologies, the applications and system labs translates expanding network requirements into leading edge cabling solutions that perform beyond the standard. Similarly, to exceed your expectations in real world applications, the materials lab develops advanced proprietary materials and process technologies that result in superior application performance that you can see and hear. The technology showcase displays the results of these labs along with industry-available equipment shown in actual segment usage, such as data center, security, and enterprise spaces. The TEK Center is a part of an extensive global R&D network with similar laboratories found throughout Nexans Inc. Berk-Tek, A Nexans Company 132 White Oak Road, New Holland, PA