Additionally, new requirements for interconnected power grids (ac or dc) have been added to Article 705, Interconnected Electric Power Production Sources.
Expansion of AFCI and GFCI protection. Ground fault circuit interrupters (GFCIs) have been included in the NEC since the 1971 edition and can be directly linked to the reduction of shock injuries and electrocutions in homes, on construction sites, around swimming pools, and in other locations where there is an elevated shock hazard. The 2017 NEC expands protection to more than just single-phase, 125 volt, 15- and 20-ampere device configurations. Substantiation citing the shock hazards in workplaces is not limited to only those device ratings; the expansion will cover single- and three-phase configurations used on systems where the voltage to ground does not exceed 150 volts and the current rating for the devices is up to 50 amperes for single-phase and up to 100 amperes for three-phase.
Arc fault circuit interrupters (AFCIs) first appeared in the 1999 NEC and were introduced to further reduce home fires of electrical origin resulting from damaged branch circuit wiring, extension cords, and the flexible cords of end-user equipment such as appliances, televisions, and portable lamps. This protection was expanded into dormitories in the 2014 NEC and is slated for expansion into hotel and motel guest rooms and suites in the 2017 edition. As in a home, the new requirement for guest rooms and guest suites covers only circuits rated 120 volts, 15- and 20-amperes.
Increased safety for workers and first responders. New and revised requirements covering workspace and labeling will be included in the 2017 NEC, continuing a trend to improve safety for those who service and maintain electrical systems and may be performing justified work on energized equipment.
Recognizing that not all such equipment is at grade or floor level, rules for “limited access” workspace covering equipment located in spaces above ceilings and in crawl spaces have been added. A new requirement for labeling of service equipment with the available fault current and clearing time of the overcurrent protective device provides vital information to workers for determining the necessary level of personal protective equipment based on the selection methods provided in NFPA 70E®, Electrical Safety in the Workplace®.
Rapid shutdown of photovoltaic (PV) system conductors was added in the 2014 NEC to provide first responders with a way to reduce the power of PV systems to a level that did not create a shock or arc-flash hazard. Further refinement of this requirement in the 2017 NEC includes requirements on the location of the rapid shutdown initiation device, the required level of voltage reduction based on the proximity to the PV modules, and on marking the location of the rapid shutdown initiation device.
For more information on these and other proposed 2017 NEC changes, visit the document information page and click on the “Next Edition” tab.
JEFFREY SARGENT is regional electrical code specialist for NFPA.