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.
- 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.
Other 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).
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).
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.
250.194: Grounding and Bonding of Fences and Other Metal Structures: This is a new section intended to provide minimum requirements for grounding and bonding of metal fences in or surrounding substations. Where the minimum requirements listed do not address all potential step, touch, and transfer voltages, alternate designs performed under engineering supervision are permitted for grounding and bonding of metal fences.
Article 300: General Requirements for Wiring Methods and Materials
300.38: Raceways in Wet Locations above Grade: This section was added to clarify that the interior of raceways installed in wet locations above grade for systems over 1,000 V shall be considered wet locations. This now aligns with Article 300.9 for wiring methods of 1,000 V or less.
Article 310: Conductors for General Wiring
Table 310.15(B)(3)(a): Adjustment Factors for More Than Three Current-Carrying Conductors: This section was updated to include spare conductors in the calculation. At the same time, it no longer requires the inclusion of conductors terminated at electrical devices that cannot be simultaneously energized, as may be the case with 3-way switches.
310.15(B)(3)(c): Raceways and Cables Exposed to Sunlight on Rooftops: An important exception was added that explains that XHHW-2 insulated conductors are not subject to this specific ampacity adjustment.
310.15(B)(7): 120/240-Volt, Single-Phase Dwelling Services and Feeders: This section received an overhaul. The table of conductor sizes based on service or feeder rating was removed. Also, four requirements that introduce a new 83% adjustment factor were added.
Article 348: Flexible Metal Conduit: Type FMC
348.30: Securing and Supporting: Exception No. 4 was expanded to allow listed FMC fittings as a means of support, which, practically speaking, means lighting fixture whips in suspended ceilings no longer require supplemental supports. This revision was also applied to Articles 350.30 for LFMC and 356.30 for LFNC.
Article 376: Metal Wireways
376.22(B): Adjustment Factors: Wording was added in this section to clarify the intent. The adjustment factors provided are intended to compensate for ampacity issues related to heat so they apply only where the number of current-carrying conductors exceeds 30 at any cross section of the wireway.
New Article 393: Low-Voltage Suspended Ceiling Power Distribution Systems
Take note of this new section if you specify or install suspended ceiling power distribution systems (30 Vac or less, or 60 Vdc or less). Key points are that the system must be:
- Limited to Class 2 power levels (refer to NEC Chapter 9)
- Installed in indoor dry locations only
- Listed for use in plenums when installed in other spaces used for environmental air in accordance with 300.22(C).
Article 404: Switches
404.2(C): Switches Controlling Lighting Loads: This section was expanded significantly to identify where grounded circuit conductors (neutrals) for controlled lighting circuits are not required. Non-habitable rooms or bathrooms, lighting that is automatically controlled, and switches that control receptacle loads do not require neutral conductors at the switch location.
Article 406: Receptacles, Cord Connectors, and Attachment Plugs (Caps)
406.3(E): Controlled Receptacle Marking: This section was added for receptacles that are automatically controlled, most commonly required by energy codes. Figure 4 shows the standard symbol for marking controlled receptacles, which is required to be visible after the installation.
[subhead2]406.9(B)(1): 15- and 20-Ampere Receptacles in a Wet Location: The text “for other than one- or two-family dwellings” and “where installed on an enclosure supported from grade” was removed from this section. Removing this text effectively requires all receptacles in a wet location to have an extra-duty weatherproof outlet box hood installed.
Article 445: Generators
445.11: Marking: The requirements for power factor, subtransient and transient impedances, insulation system class, and time rating were moved to a separate paragraph specifically for generators rated more than 15 kW. Factory-applied or field-applied markings are now also required to indicate whether or not the generator neutral is bonded to the generator frame.
Article 450: Transformers and Transformer Vaults (Including Secondary Ties)
450.10(A): Dry-Type Transformer Enclosures: This section was added to the transformer grounding subsection and requires a terminal bar located inside the transformer enclosure for separate equipment grounding conductors and supply-side bonding jumpers. An exception is provided for dry-type transformers equipped with wire-type connections (see Figure 5).
Article 501: Class I Locations
501.145: Receptacles and Attachment Plugs, Class I, Divisions 1 and 2: This section now clearly distinguishes between requirements for receptacles and attachment plugs in an effort to make hazardous installations safer. Receptacles are now required to be part of the premises wiring unless specifically permitted under Article 501.140(A): Flexible Cords, Class I, Divisions 1 and 2. A similar clarification was made for Class II locations in Article 502.145: Receptacles and Attachment Plugs. This should alleviate some of the risk involved with temporary or portable assemblies that may be fabricated in the field for maintenance or troubleshooting in hazardous environments.
Article 517: Health Care Facilities
A number of revisions were made to this article to better align with NFPA 99: Health Care Facilities Code. Among the revisions are changes to the quantity of receptacles required in general care and critical care areas as well as a general substitution for the term “emergency system” with “essential electrical system.”
Article 600: Electric Signs and Outline Lighting
600.6: Disconnects: A permissible location was added to this section. The disconnect may now be located at the point the feeder or branch circuit enters the sign enclosure or pole and must disconnect all wiring supplying the sign.
New Article 646: Modular Data Centers
Mission critical designers and installers take note. This article was introduced to regulate a growing trend toward preassembled and packaged data center enclosures. Given the scope and size of modular data centers, Article 646 covers a wide range of requirements from nameplates to lighting, as well as working-space clearances for electrical equipment, information technology equipment, and batteries.
Article 690: Solar Photovoltaic (PV) Systems
Numerous revisions were made to this article, but one of the main changes from a designer/specifier’s perspective is the rewording of Section 690.17: Disconnect Type (formerly “Switch or Circuit Breaker”). This section now provides very specific requirements for the listing of the disconnect type as well as the operation and ratings of the device.
Article 700: Emergency Systems
700.8: Surge Protection: This is a new subsection that requires a listed surge-protective device to be installed in or on all emergency system switchboards and panelboards.
700.16: Emergency Illumination: Language added to this section requires emergency illumination at the disconnecting means for buildings supplied by feeders, branch circuits, or service-entrance conductors where the disconnecting means is installed indoors. Emergency lighting is essential for egress as well as emergency response personnel. This new requirement highlights the importance of this lighting at the building disconnecting means.
New Article 728: Fire-Resistive Cable Systems
This new section covers the installation of fire-resistive cables and conductors. While the majority of the text reinforces the general requirement for the components to be listed as a complete system, it should also be noted that cables and conductors are required to be surface-marked with the suffix “FRR” (fire-resistive rating).
New Article 750: Energy Management Systems
In line with other updates in the 2014 NEC related to energy codes, this new article addresses the installation and operation of energy management systems. Because the two main components of an energy management system are monitoring and control, the intent of these new requirements is to provide a set of standards to ensure continuity for critical systems, such as fire pumps, health care facilities, and other emergency systems.
This article cannot cover every change in the 2014 NEC. However, it emphasizes some of the significant updates that affect most electrical and power professionals. For more in-depth commentary on the NEC text, NFPA 70HB14 is highly recommended.
Andy Chavez is electrical discipline manager at CH2M HILL. He has more than 10 years of experience designing industrial facility projects in such markets as electronics, data centers, consumer products, research laboratories, and transportation.