Reviewing the 2014 NEC

It’s time for electrical and power engineers to start reviewing the 2014 edition of the NEC to be prepared for when jurisdictions adopt it as local code.


This article has been peer-reviewed.Learning objectives

  • Understand the key changes in the 2014 edition of NFPA 70: National Electrical Code.
  • Learn about the articles in the code that should be paid particular attention.

Has it been 3 years since the 2011 edition of NFPA 70: National Electrical Code (NEC) was published? As electrical engineers, designers, or installing contractors, that means it is time to start reviewing the 2014 NEC to understand the key changes and subtleties before the majority of jurisdictions adopt it as local code. Even if your local jurisdiction has no plans to adopt the 2014 NEC anytime soon, it is important for electrical professionals to understand the changes and stay current with evolving technologies and the latest safety standards. The 2014 edition of the NEC was approved as an American National Standard on Aug. 21, 2013, and supersedes all previous editions. Because a strong understanding of the NEC is a cornerstone of any safe electrical design, this article will focus on some of the more significant changes proposed and accepted in this code cycle.

But first, a broad change throughout this edition of the code is that the threshold for higher voltage equipment has increased from 600 V to 1,000 V (refer to the revised definition for “High Voltage” in Article 490). This change is largely attributed to alternative energy systems operating at more than 600 V for increased efficiency and performance. As before, Article 690 for solar photovoltaic (PV) systems and Article 692 for wind electric systems require compliance with Article 490 for systems exceeding this new high-voltage threshold.

Article 100: Definitions

One of the many terms that received an overhaul is “Coordination (Selective).” This definition has been revised to clarify that selective coordination applies to the full range of overcurrents, including overload and fault currents. While the definition does not require anything new from a technical perspective, it is important to note that Articles 700.28: Selective Coordination for Emergency Systems, 701.27: Selective Coordination for Legally Required Standby Systems, and 708.54: Selective Coordination for Critical Operations Power Systems (COPS) have added wording that require the device settings to be selected by a licensed professional engineer or similarly qualified person. These sections now specifically require the coordination study to be properly documented and made available for review by the authority having jurisdiction.

Figure 1: Examples of acceptable field-applied hazard markings required by Article 110.21(B) are based on the guidelines of ANSI Z535.4-2011. All graphics courtesy: CH2M HILLOther key definitions that have been added or modified include “readily accessible,” “ground-fault current path,” “industrial control panel,” “photovoltaic (PV) system,” “retrofit kit,” “separately derived system,” “substation,” and “switchgear” (formerly “metal-enclosed power switchgear”).

Article 110: Requirements for Electrical Installations

110.21(B): Field-Applied Hazard Marking: Specific language was added to help regulate field-applied hazard labels. These labels must adequately warn of the hazard, be permanently affixed to the equipment or wiring method, shall not be handwritten, and should be resilient enough to endure the surrounding environment. New informational notes reference ANSI Z535.4-2011: Product safety signs and labels for suitable label guidelines (see Figure 1).

110.26(C)(3): Personnel Doors: In this section, the equipment current rating is reduced from 1,200 A to 800 A at which the egress door(s) shall have listed panic hardware. While the NEC is not automatically retroactive to existing installations, this requirement guarantees many new doors will need to open in the direction of egress and be specified with listed panic hardware. It is important to remember this requirement is not specific to electrical rooms and is driven instead by the equipment rating and proximity of working space to doors in the egress path (see Figure 2).

Figure 2: Personnel door requirements of Article 110.26(C)(3) are now based on proximity to electrical equipment rated 800 A or greater, reduced from 1,200 A in previous editions.

110.26(E)(2)(b): Dedicated Equipment Space: This section now aligns outdoor installations with indoor installations by requiring the space extending from grade to 6 ft above the equipment to be dedicated to the electrical installation. The intent of this requirement for indoor installations has always been to allow adequate space for the installation of electrical equipment, raceways, and cables (see Figure 3).

Figure 3: Dedicated equipment space is now required by Article 110.26(E)(2)(b) for outdoor equipment, similar to the requirement in Article 110.26(E)(1)(a) for indoor installations.

Article 210: Branch Circuits

210.8: Ground-Fault Circuit-Interrupter Protection for Personnel: This section received several updates. Among them, ground-fault circuit interrupter (GFCI) receptacles are now required if installed within 6 ft of any dwelling unit bathtub or shower stall, and are required in laundry areas. The GFCI requirement was also expanded for non-dwelling unit garages, no longer specific to receptacles installed for the use of hand tools. Finally, dwelling unit dishwashers now must be GFCI protected.

210.12: Arc-Fault Circuit-Interrupter Protection: Dwelling unit kitchens and laundry areas were added to the list of arc-fault circuit interrupter (AFCI) protected locations. Section (B): Branch Circuit Extensions or Modifications – Dwelling Units added an important exception that reduces the burden of adding AFCI protection when replacing a panel as long as existing circuits are not extended more than 6 ft and no outlets or devices are added.

210.19: Conductors – Minimum Ampacity and Size: A statement in 210.19(A)(1)(b) was added to help clarify the sequence of branch circuit conductor size calculations. Conductors shall be sized for the maximum load after applying adjustment or correction factors. Articles 215.2 for feeder conductor sizing and 230.42 for service-entrance conductor sizing added similar language. This simple clarification should alleviate questions from designers and reduce the many interpretations from engineers and code officials alike.

Article 220: Branch-Circuit, Feeder, and Service Calculations

220.12: Lighting Load for Specified Occupancies: An important exception was added to this section that allows lighting loads to be calculated using local energy code values as long as a power monitoring system is installed that alarms when the energy code is exceeded and the demand factors in Article 220.42: General Lighting are not applied to the calculation. This finally allows some wiggle room in load calculations and reflects the new reality of energy-optimized lighting systems.

Article 225: Outside Branch Circuits and Feeders

225.36: Type: The type of disconnecting means for feeders or branch circuits supplying buildings or other structures was revised to clarify that a feeder or branch circuit disconnecting means must be suitable for use as service equipment only where the feeder/branch circuit grounded conductor is used as the return path for ground-fault current. The type of disconnecting means was also clarified from the previous edition to include circuit breakers, molded case switches, general-use switches, snap switches, or other approved means.

Article 240: Overcurrent Protection

240.87: Arc Energy Reduction: This section was revised from the previous edition’s “Non-instantaneous Trip.” The section now states that documentation and a method to reduce clearing time is required for circuit breakers rated 1,200 A or higher. Two methods to reduce clearing time have been added: an energy-reducing active arc flash mitigation system and an approved equivalent means, leaving the door open for future technologies.

Article 250: Grounding and Bonding

250.64: Grounding Electrode Conductor Installation: A sentence was added in section (B) that clarifies grounding electrode conductors and associated bonding jumpers are not required to comply with Article 300.5, including the minimum cover requirements of Table 300.5.

250.68(C): Grounding Electrode Connections: This section was renamed from the previous “Metallic Water Pipe and Structural Metal” and now includes wording that allows a concrete-encased electrode to extend to an accessible location above the concrete.

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DON , PA, United States, 01/08/15 09:27 AM:

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