Understanding the NEC 2014 and Its Impact on PV Systems

The continued safety, growth and success of the solar industry requires that PV systems be designed and installed to meet the minimum standards set forth in NFPA 70, which is more commonly known as the National Electrical Code. It is always exciting when a new version of the NEC is finally available, as this document represents the culmination of years of hard work by many individuals and organizations. It also sets the stage for evolving design and installation practices. The goal of these changes is to make PV systems safer for building owners and occupants, service technicians and first responders. While an updated edition of the NEC is published every 3 years, adoption dates for new editions vary significantly by state or local jurisdiction.

The National Fire Protection Association (NFPA) was established in 1896 with the goal of reducing the burden of fire and other hazards. Since 1911, this nonprofit organization has sponsored development of the NEC, which documents mandatory and permissive standards meant for enforcement by governmental bodies that have legal jurisdiction over electrical installations. The Code is a consensus document developed from public input. While volunteer members of technical committees known as Code-Making Panels (CMPs) vote on all additions, deletions or other changes to the NEC, the Code-making process includes a public review and comment period. (For more information on this process, see “Code Red: Notable Changes in the 2011 NEC,SolarPro magazine, April/May 2011.) CMP No. 4 is responsible for Article 690, “Solar Photovoltaic (PV) Systems,” and Article 705, “Interconnected Electric Power Production Sources,” which are of particular interest to PV system designers and installers, as well as Articles 225, 230, 692 and 694.

Here we focus on the most significant NEC 2014 changes related to the design and deployment of PV systems, particularly those found in Articles 690 and 705. We also discuss some general Code changes from Chapters 1 through 4. Since the scope of this article is selective rather than encyclopedic, there are many NEC 2014 changes that we do not touch on. Unless logic dictates otherwise, we discuss the revised Code sections in numerical order.

Note that the usual caveats apply. As discussed in NEC Section 90.1(B), simply meeting the minimum requirements outlined in the NEC is no guarantee that an electrical installation will prove adequate. For a PV system to perform efficiently and reliably over time or to be aesthetically pleasing, PV system designers and installers may need to adhere to industry best practices that exceed minimum Code requirements. The final arbiter regarding the acceptability of electrical equipment and installation methods is always the local AHJ. While we interviewed members of CMP No. 4 and other industry subject matter experts to help explain the intent and implications of some of the most intricate NEC 2014 revisions, the interpretations presented here are just well-informed opinions come inspection time. Ultimately, the opinion that matters is the AHJ’s.

General Code Changes

As outlined in Section 90.3, NEC Chapters 1 through 4 apply generally to all electrical installations and are modified or supplemented by the special requirements found in Chapters 5 through 7.

Article 100 “Definitions”

Though referred to in numerous other Articles, prior to NEC 2014, the definition of a photovoltaic system resided in Article 690. As part of the 2014 cycle of revisions, the NEC Technical Correlating Committee (TCC) directed CMP No. 4 to move the definition of solar photovoltaic system from Section 690.2 to Article 100, which includes terms that are used in two or more Articles. In the process, CMP No. 4 eliminated the word solar from the definition and added the abbreviation PV to set the stage for its use elsewhere. As a result, a new entry in Article 100 defines a photovoltaic (PV) system as: “The total components and subsystem that, in combination, convert solar energy into electric energy suitable for a connection to a utilization load. “

Section 110.21(B) “Field-Applied Hazard Markings”

Electrical systems in general, and PV systems in particular, require numerous plaques, labels, directories and signs. In practice, the materials that contractors use for field-applied signs or labels range from the clearly inadequate (laminated paper used in outdoor locations) to exemplary (engraved metal). Further, different contractors and facility operators tend to use different styles for labels, in terms of both the label color and the text color, size and font.

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