Every three years, the National Electrical Code (NEC) is revised and often expanded. As the 2017 NEC development cycle comes to a close, the final stages of the process unfold. This article is the first in a series that will provide a concise look at some of the significant revisions and new requirements included in this edition. Visit www.ecmag.com/magazine/articles/article-detail/codes-standards-2017-nec-significant-changes for this full series.


The NFPA received 4,012 public inputs (PIs) recommending Code changes, and 1,235 first revisions (FRs) resulted. There were 1,513 public comments submitted, yielding 559 second revisions (SRs). Nine new articles were proposed, and five new articles emerged in the 2017 NEC. 


Many of the changes and new rules in this edition specifically address new technologies, such as expanded use of energy-storage systems and equipment; microgrid installations; and large-scale, photovoltaic (PV) system installations. The following is a summary of the new articles in the 2017 NEC.


Article 425—Fixed Commercial and Industrial Process Heating Equipment


This article covers fixed, industrial process heating employing electric resistance or electrode-heating technology. For the purpose of this article, heating equipment includes boilers, electrode boilers, duct heaters, strip heaters, immersion heaters, process air heaters or other approved fixed electrical equipment used for industrial process heating. 


Article 691—Large-Scale, PV Electric Supply Stations


This article will cover the installation of large-scale PV electric supply systems operated for the sole purpose of providing electric supply to the utility transmission or distribution system with an output power rating of no less than 5,000 kilowatts (kW). Electric supply stations contain the generating stations and substations, including their associated generator, storage battery, transformer and switchgear areas. Facilities covered by this article have specific design and safety features unique to large-scale PV facilities. 


Article 706—ESSs


This article covers all permanently installed energy-storage systems (ESSs), which may be stand-alone or interactive with other electric power production sources. An ESS is defined as a device or more than one device assembled together capable of storing energy for future use. ESSs include but are not limited to electrochemical storage devices (e.g., batteries), flow batteries, capacitors and kinetic energy devices (e.g., flywheels and compressed air). These systems can store alternating current (AC) or direct current (DC) for output and can include inverters and converters to change stored energy into electrical energy. 


Article 710—Standalone Systems 


This article includes requirements for electric-power-production sources operating in the stand-alone mode. An important provision in this new article conveys that—even though the system may not be connected to a serving utility—the system must be adequate to meet NEC requirements as if it were supplied by a feeder or service. All equipment installed for these systems must be listed or labeled. 


Article 712—DC Microgrids


This article covers DC microgrids, defined as power-distribution systems consisting of one or more interconnected DC power sources, DC-to-DC converters, DC loads and AC loads powered by DC-to-AC inverters. A DC microgrid is typically not directly connected to an AC primary source of electricity, but some DC microgrids interconnect with one or more DC-to-AC bidirectional converters or DC-to-AC inverters.


ARTICLE 90—INTRODUCTION

Section 90.2(A) Covered


The words “and removal” have been added in the first sentence of 90.2(A). This addition expands the NEC’s scope beyond installation requirements to include requirements addressing equipment removal. Current NEC rules require removal of equipment such as those for temporary power wiring removal and those for abandoned communications cables removal. 


Section 90.3 Arrangement
and Figure 90.3


Section 90.3 and associated Figure 90.3 have been revised. The revision clarifies that chapters 5–7 may modify or supplement requirements in chapters 1 through 7. The rules in chapters 5–7 can supplement or modify each other in addition to the provisions in chapters 1–4. 


For example, Article 770 contains requirements for optical fiber cables, and Section 770.3(A) indicates listed optical fiber cables shall be permitted in hazardous (classified) locations, and the cables shall be sealed in accordance with the requirements of 501.15, 502.15, 505.16 or 506.16, as applicable.


Look for part 2 of this series in September. Visit http://goo.gl/U3vLo7 to view all proposed revisions.