NFPA 70: National Electrical Code (NEC), 2017 edition

Sept. 6, 2016

Cover of 2017 NFPA 70
Guest Post by: Bobby Gray*

2017 Edition Released

NFPA 70®, National Electrical Code®, or the NEC® as it is more commonly known, is the most widely used technical document in the world. Since it was first published in 1897, it has been helping to protect both people and property from hazards associated with electrical energy by providing safe installation practices for electrical equipment and systems. 

The National Fire Protection Association (NFPA) publishes an updated version of the NEC® every three years. After incorporating the efforts of the general public and more than 300 volunteer members of code-making panels, the 2017 edition has been released for adoption into local statutes by governmental bodies that have legal jurisdiction over electrical installations.

New Articles

As new technology is introduced, the NEC® must evolve to address the ever-changing industry. This cycle, the NEC® added five new articles in response to either existing challenges or anticipated systems. 

  1. Article 425, titled Fixed Resistance and Electrode Industrial Process Heating Equipment, provides installation rules for industrial heating equipment not addressed elsewhere in the code. 
  2. Article 691 provides installation rules for Large-Scale Photovoltaic (PV) Electrical Power Supply Stations. These systems are privately owned and no smaller than 5000 kW in size. 
  3. Article 706, Energy Storage Systems (ESS), accommodates those systems that are intended for short term augmentation of the utility supply during peak consumption times. 
  4. Article 710, Stand-Alone Systems, is a small article that addresses any small alternative energy supply systems such as wind machines, photovoltaic systems, or others where other NEC® articles are not sufficient to provide the necessary installation rules. 
  5. Finally, Direct Current Microgrids, Article 712, provides for small direct current systems that are being used where security from outside threats are a concern. This new article ensures the systems will provide reliable and safe service in a critical function.

New and Clarified Rules

In addition to the new articles, the 2017 NEC® provides clarification to existing rules as well as new rules that will reduce the risk of fire or electrical hazard exposure to workers. Following are some of the key changes [citations in brackets]:

  • An arc flash warning label that contains detailed information about the electrical system must now be attached to service equipment to inform workers of potential arc flash hazards. [110.16(B)]
  • Reconditioned electrical equipment must be marked with information about the reconditioning manufacturer as well as performance data to certify quality. [110.21(A)(2)]
  • Working space for the protection of a worker providing service or maintenance is defined for electrical equipment operating between 601 volts and 1000 volts, and for equipment located in limited areas such as above dropped ceilings. [110.26(A)(4) and Table 110.26(A)(1)]
  • The distance from a sink to a location where an installed receptacle must have Ground Fault Circuit Interrupter protection is clarified to not include those located under the sink. [210.8]
  • The use of Arc Fault Circuit Interrupter protection has been expanded to reduce the risk of fire in dwelling units. [210.12(B)]
  • Meeting rooms now will have a minimum number of receptacles to limit the use of extension cords. [210.71]
  • The temperature adder to correction factors for conductors installed on the roof is removed so long as the raceway is installed at least 7/8” above the roof surface. [310.15(B)(3)(c)]
  • The rule prohibiting flexible cords above a dropped ceiling has been relaxed for equipment that is listed for environmental air spaces, permitting some projectors mounted on the ceiling to be fed from above the dropped ceiling. [400.12(5) Exception]
  • Tamper resistant receptacle rules have expanded to more areas and configuration of receptacles where children may have access. [406.12]
  • The ground fault trip threshold has been reduced for circuits supplying marinas and boat docks in response to recent electrocutions occurring at those locations. [555.3]
  • There are new rules that require a rapid shutdown of photovoltaic systems to protect the emergency response personnel such as fire fighters from the electrical hazards associated with those energized systems. [690.12]


These are just a few of the many revisions to the NEC® that users of the code have determined necessary to further the scope and purpose of the National Electrical Code®. For more information on the effects of these and other changes, enroll in one of these classes sponsored by Dade Moeller, an NV5 Company:

*Bobby Gray is a principal member of technical committees for NFPA 70E, Standard for Electrical Safety in the Workplace®; NFPA 79, Electrical Standard for Industrial Machinery®; and NFPA 70, National Electrical Code®; he also is the current chair of Code Making Panel 18. Bobby works with Dade Moeller/NV5 to bring joint safety solutions to our clients.