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August 13, 2018

NEC 2017 - What it Means in 2018

For the 2017 version of the NEC, NFPA received 4,012 public inputs recommending code changes that resulted in 1.235 first revision changes resulting in 1,513 public comments on those which then resulted in 559 second revisions. Hence the expanse of time. Five completely new articles were introduced. The new articles are centered around newer technologies like microgrids and energy storage systems that didn’t exist or were not addressed in prior versions.

As of August 1, 2018, the 2017 version of the code is in effect in 23 states. Others are beginning adoption.

As for the cable plant portion of the code document, a few things have changed as well. The first notable change is the clause that requires the removal of abandoned cable. While it was mentioned in previous documents, the removal clause is now in the first paragraph in Article 90 along with addressing equipment removal. It is simply no longer hidden.

Also highlighted is Arc Energy (Arc Flash) reduction. This applies to all fuses with a rating equal to or greater than 1,200A although the implementation dates are set for 2020. Arc flashes have been blamed for more than one data center fire in recent times, and regardless of the environment fixing or lessening the danger continues to be addressed in this and potentially the next version.

There is a new article addressing Photovoltaic systems. Both small and large-scale systems, how they are labeled, disconnect requirements and shutdown are all addressed. This is a new article introduced in this version of the code.

Perhaps the biggest confusion comes from the Power over Ethernet (PoE) specifications and the new LP cables that have been developed which are included as an OPTION. PoE now comes in more than one type and more than one class. The ability to provide power over traditional cables eliminates addition power receptacles and an AC to DC conversion. IEEE 802.3af provided for 12.94W at the end device, while 802.3at provided for 25.50, newer 4 pair (4PPoE) defined in 802.3bt provides for 51W and Type 4 also defined in the same standard provides for 71W of delivered power. Note, Type 3 launches up to 60W and Type 4 launches100W. Beginning with the very first iterations of PoE, safety has been a key concern and as such, heat buildup in tight bundles of cable was studied. The NEC provides an ampacity table to assure that the conductors in the cables will support the transmission. While not normally required, the cables can be used as an option provided the ampacity table (724.144 in the 2017 NEC) is supported by the conductors. In this version of the code, LP cables must carry the LP suffix on the cable jacket. Listings for LP rated cables are verified by UL and must carry the ampacity per conductor designation. Both category (non-LP rated) and LP cables can be used in most installations provided the cable meets the ampacity ratings.

There is no requirement for LP cable for most installations and there is a misconception in the marketplace that LP cables are required for Class 3 or 4 PoE applications. In general, unless bundles are greater than 192 cables, LP cables are an option as long as they comply with the currently limits. Note that the current limit of an LP cable will often be less than the ampacity permitted by the ampacity table for small bundle sizes of the same cable. It is also a misconception that the cable governs the power exclusive of the connector. RJ45 jacks have a general limit of 1.3 Amperes per contact and this may provide the actual limit rather than the conductor limits.

For cabling to support PoE in any iteration, consider not only the power, but also the distances supported, the protocols supported and the connectors at the ends. For our whitepaper on PoE applications featuring the GameChanger cable, visit

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