Codes and Standards

Understanding the changes to NFPA 70-2020

New requirements of the 2020 edition of the National Electrical Code will affect facility design

By Tom Divine, PE, LEED AP December 29, 2020
Courtesy: Johnston, LLC

 

Learning Objectives

  • Understand the changes to the 2020 National Electrical Code that will likely impact design of commercial buildings.
  • Learn the new labeling requirements for switchboards, switchgear and panelboards.
  • Know the new design requirements for services with multiple disconnecting means.

The 2020 edition of NFPA 70: National Electrical Code was issued in August 2019. It has gone into effect already in several states and is scheduled for adoption by more jurisdictions in the coming months.

The new edition includes four new articles, hundreds of individual revisions and additions to the scope of the code. This article is by no means a complete exposition of the changes to the 2020 NEC. Rather, it covers those changes with broad impact on the design of electrical systems for commercial facilities.

Article 310

Article 310, conductors for general wiring, was extensively reorganized, with little in the way of substantive changes. The scope of the Article was limited to conductors rated 2,000 volts and below. Requirements for conductors rated higher than 2,000 volts were removed from Article 310 and relocated to new Article 311, medium-voltage conductors and cable, without substantive changes.

Ampacity tables for conductors rated 2,000 volts and below were renumbered. Tables 310.15(B) 16  through 21 were renumbered to 310.16 through 310.21 — the same numbering applied to these tables for multiple code cycles before their 2011 revisions. In particular, the table of allowable ampacities of insulated conductors in conduit — the workhorse ampacity table for building design — was returned to its historic location as Table 310.16.

Insulation types XHHN, XHWN and XHWN-2 were added to the list of acceptable types for dry and damp locations in 310.10(B) and for wet locations in 310.10(C) and to ampacity tables 310.16 through 310.20. 310.15(A), formerly 310.15(B), contains text permitting interpolation of ampacities of conductors not found in the tables, under engineering supervision, based on the cross-sectional area of adjacent conductors in the table and the cross-sectional area of the conductor of interest. Cross-sectional areas of standard AWG conductors can be found in Chapter 9, in table 8

Article 311, medium-voltage conductors and cable , covering requirements for conductors nominally rated between 2,001 and 35,000 volts, was added to the 2020 edition. In the previous edition, requirements for medium-voltage conductors appeared in both Article 310 and Article 328, medium-voltage cable: type MV. Medium-voltage requirements of Articles 310 were consolidated with the contents of Article 328, without substantive changes, to clarify requirements and improve usability. Article 328 was deleted in its entirety.

Figure 1: An unlisted generator set, rated below 600 volts, would not comply with NFPA 70: National Electrical Code Section 445.6. Courtesy: Johnston, LLC

Figure 1: An unlisted generator set, rated below 600 volts, would not comply with NFPA 70: National Electrical Code Section 445.6. Courtesy: Johnston, LLC

Section 210.8

For several code cycles, each successive edition of the code has expanded the requirements for ground-fault circuit interrupter protection for personnel. The 2020 edition is no exception. Section 210.8(B), GFCI protection for personnel, describes requirements for GFCI protection of receptacles in facilities other than dwelling units, in terms of their ratings and provides a list of locations where the requirement applies.

The 2020 edition requires GFCI protection for “All 125- through 250-volt receptacles supplied by single-phase branch circuits rated 150 volts or less to ground, 50 amperes or less and all receptacles supplied by three-phase branch circuits rated 150 volts or less to ground, 100 amperes or less, installed in the locations specified,” in the remainder of 210.8(B). The text has been clarified in the 2020 edition, but the requirements are functionally identical to those of the 2017 edition.

Section 210.8(B)(2), in the 2017 edition, requires GFCI protection for receptacles in kitchens. The 2020 edition adds the text, “or areas with a sink and permanent provisions for either food preparation or cooking,” to that requirement. This language covers more locations than does the Article 100 definition of a kitchen and includes such locations as coffee shops and delicatessens — spaces provisions for cooking, but with sinks and provisions for food preparation. The language is broad enough to include employee break rooms, as open counter space may be seen by an authority having jurisdiction as a provision for food preparation. It remains to be seen how this requirement will be enforced in practice.

New locations requiring GFCI protection in the 2020 edition include indoor damp locations, accessory buildings, laundry areas and locations within 6 feet of a bathtub or shower stall.

Section 210.8(D), formerly covering dishwasher circuits in dwelling unit kitchens, has been expanded to cover a list of specific appliances referenced in Section 422.5(A) and now applies to all dishwashers. This section adds a specific requirement for receptacles serving vending machines, calling for GFCI protection when GFCI protection is not provided in or very near the machines supply plug, regardless of whether the vending machine has internal GFCI protection.

Figure 2: This sample label is compliant with NFPA 70: National Electrical Code Section 408.6. Courtesy: Johnston, LLC

Figure 2: This sample label is compliant with NFPA 70: National Electrical Code Section 408.6. Courtesy: Johnston, LLC

Section 220.12

Section 220.12, lighting load for specified occupancies in the 2017 edition, in Article 220, branch-circuit, feeder and load calculations, has been extensively revised. This section prescribes minimum lighting power densities that must be accommodated in the service ampacity for a variety of occupancy types. Occupancy types and lighting power densities are shown in Table 220.12, general lighting loads by occupancy.

Minimum LPDs shown in Table 220.12 have seen few revisions during the roughly 50 years that the table has been part of the code. During that time, U.S. jurisdictions have adopted energy codes mandating maximum LPDs considerably lower than the entries in the table, driven by dramatic improvements in lighting efficacy. The conjunction of high minimum LPDs required for service ampacity calculations and low maximum LPDs of the energy codes can lead to apparent contradictions in which an AHJ may enforce one code requiring a larger service to accommodate lighting loads and another prohibiting installation of those same loads.

For the 2020 edition, dwelling units were removed from Section 220.12 and relocated to section 220.14(J), other loads – all occupancies. Section 220.12 was renamed “lighting load for nondwelling occupancies,” and the table was renamed “general lighting loads by nondwelling occupancy.” The list of occupancies was enlarged to generally align with Table 9.5.1, lighting power density allowances building area method, of ASHRAE 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings, 2016 edition. The minimum LPDs of Table 220.12 were revised to generally reflect those values from ASHRAE 90.1-2001. A new note to Table 220.12 states that a 125% multiplier is included in the table values and a list of new notes provides a cross-reference between the occupancy list of the 2017 table and the 2020 version.

In the 2017 edition, an exception to Section 220.12(B) allowed the service ampacity calculation to be based on the LPDs shown in the energy code adopted by the local jurisdiction in lieu of the values in Table 220.12, provided that a power monitoring system, configured to alert building management and automatically reduce load when lighting loads exceed energy code levels and that the demand factors of Table 220.42, lighting load demand factors, are not applied in calculating the lighting load. The 2020 edition deletes the requirement for automatic load reduction and adds the condition that the 125% continuous load factor is applied to the lighting load. New text has been added to Section 220.12(A) requiring that motors sized at less than 1/8 horsepower be considered to be part of the lighting load.

Table 240.42, lighting load demand factors, was revised to increase demand factors for hotels and similar facilities. Hospitals were deleted from the table entirely.

Section 230.71

The venerable “six-handle rule” for services, a part of the NEC for more than 80 years, has been substantially modified in the 2020 edition. Section 230.71, services, maximum number of disconnects, in the 2017 edition allowed up to six service disconnects installed in a single enclosure, separate enclosures or in switchboards or switchgear, without restriction as to how many disconnects might be installed in a single equipment item.

Section 230.71 still permits up to six disconnecting means for a single service, but adds restrictions requiring some form of physical barrier between disconnects. The service disconnecting means must now be installed in separate enclosures or panelboards, separate compartments of switchgear or metering centers or in separate vertical switchboard sections with barriers separating each vertical section.

In a related revision, the requirement for barriers on service buses and service terminations in service equipment in Section 408.3(A)(2), switchboards, switchgear and panelboards, was relocated to Section 230.62(C) in the 2020 edition. In 2017, Section 408.3(A)(2) contained an exception abrogating the requirement for barriers when multiple service disconnects were installed in the same enclosure. Because that exception would conflict with the revisions to 230.71 requiring service disconnects to be installed in separate enclosures, it has been omitted from the 2020 edition.

This change is intended to reduce the likelihood of inadvertent contact energized parts by personnel, tools or equipment during maintenance activities in service equipment. With multiple service disconnects installed in a single enclosure, it is impossible to use safe work practices on energized equipment. De-energization of the line side of service equipment can generally be accomplished only by the serving utility and often requires an extended outage. In an enclosure with a single disconnect, with line-side barriers, load terminations can be deenergized by on-site personnel and the equipment can be made safe for maintenance or construction activities on load terminations.

Figure 3: These panelboards require a label showing available fault current and the calculation date to comply with NFPA 70: National Electrical Code Section 408.6. Courtesy: Johnston, LLC

Figure 3: These panelboards require a label showing available fault current and the calculation date to comply with NFPA 70: National Electrical Code Section 408.6. Courtesy: Johnston, LLC

Section 110.26(C)(2)

Section 110.26(C)(2) covers requirements for entrance and egress for working spaces about large equipment rated 1,000 volts or below that contains overcurrent protection or switching devices. In the 2017 edition, a second exit was required from the working space when any single equipment item rated 1,200 amperes or more and longer than 6 feet wide. In the 2020 edition, this section is extended to invoke the second exit requirement for multiple service disconnecting means installed under Section 230.71, where, in the words of the code, “the combined ampere rating is 1,200 amperes or more and over 1.8 m (6 feet) wide.”

This new requirement applies only to service equipment and does not apply to multiple disconnects installed downstream from the service entrance. Its apparent purpose is to force inclusion of a second exit based loosely on the ampacity of the service and therefore its available fault current and arc-flash hazard, rather than on the size of individual disconnects.

The section doesn’t describe how the width of an installation with multiple disconnects is to be measured, though it seems likely that AHJs will generally consider the worst-case distance between the outside edges of all disconnects connected to the same service as the width of the service. The “combined rating” of the disconnects will presumably be the sum of the ratings of the disconnecting means, as an easily calculated, if not entirely precise, surrogate for the actual hazard. Engineers hoping to persuade an AHJ that the, “combined rating,” is something else — say, the Table 310.16 ampacity of the service conductors — should coordinate their designs with the AHJ well ahead of construction.

Additional new text in 110.26(C)(2) requires that open equipment doors not impede entry to or egress from the working space large equipment. Some equipment doors open to 90 degrees, but not further, making a quick exit from the working space more difficult from one direction. Such installations will likely require additional space for entry and egress. The Code does not specify the minimum width of the unimpeded path; reasonable values might be the 24-inch minimum width of a personnel door from Section 110.26(C)(2) or the 30-inch minimum width of the working space for nonelectrical maintenance in the rear of equipment found in Section 110.26(A). Where these issues arise, early consultation with the AHJ will avoid disappointment at construction.

Figure 4: Automatic transfer switches with hinged doors may impede entrance to and egress from the working space. Courtesy: Johnston, LLC

Figure 4: Automatic transfer switches with hinged doors may impede entrance to and egress from the working space. Courtesy: Johnston, LLC

Section 445.6

Section 445.6, new to the 2020 edition, requires that stationary generators rated 600 volts and below be listed. This requirement is absent from the 2017 edition. An exception allows for field labeling of, “one-of-a-kind or custom generators,” by a field evaluation body. In informational note references UL 2200, Stationary Engine Generator Assemblies.

Article 408

Several sections of Article 408 were revised or added to expand labeling requirements for distribution equipment. In the 2017 edition, Section 408.4(A), field identification required, circuit directory or circuit identification, required circuit directories mounted on the face or inside door of the equipment, with clear and specific information about the purpose and use of each circuit. The section has been expanded to allow an “approved location” for the directory, in addition to the two specific locations listed.

This apparently inconsequential revision may well lead to significant changes in the way that circuit directories are implemented in the field. Currently, circuit directories provide limited information about each circuit, due to restricted real estate on panelboard directory cards. NEC code-making panel 9, responsible for this section, stated in its first revisions report that the intent of this revision is to provide space for adequate information in panel directories, and suggested that compliant directories may take the form of notebooks, possibly with graphic content. In view of the undefined location available for this use, together with the broad information requirements of this section, AHJs will be able to require extended circuit information in each panel directory that may well expand to multiple pages.

Section 408.6, short-circuit current rating, is new to the 2020 edition. This section requires that switchboards, switchgear and panelboards be rated for at least the available fault current at their terminals and that they be labeled with the available fault current and the date the fault current was calculated. Sections 110.9 and 110.10 required this equipment to be rated for no less than the available fault current in the 2017 edition and those sections remain in the code. The labeling requirement was also already in force for a variety of equipment. Section 408.6 expands the scope of this requirement to Article 408 distribution equipment. With this change, AHJs will be able to verify compliance with fault duty requirements in the field.

Section 408.18(C), also new to the 2020 edition, states that equipment requiring side or rear clearances be clearly labeled with that information on the front of the equipment. Existing requirements regarding the internal arrangement of terminations and buses, to avoid any necessity of reaching across uninsulated, ungrounded buses to make terminations, were relocated from Section 408.3(D). The intent of the labeling requirement is to ensure that necessary clearances are obvious in the field to avoid installations with inadequate clearances that make compliance with termination and connection requirements impossible.

Section 517.26, Health Care Facilities, Application of Other Articles

Section 517.26 establishes that the life safety branch of a health care facility’s life safety branch must comply with the provisions of Article 700, emergency systems, except where specifically amended by Article 517. Additions to this section list specific sections of Article 700 that do not apply to health care facilities and are taken verbatim from NFPA 99: Health Care Facilities Code, 2018 edition, Section 6.7.6.2.1.5.

Of particular interest in this list is Section 700.10(D), fire protection, covering fire resistance and fire protection of emergency feeders. In the 2017 edition, fire protection of circuits was not addressed in Article 517, while 700.10(D) specifically required fire protection for feeders at, “health care occupancies where persons are not capable of self-preservation.” At the same time, health care compliance with 00.10(D) was specifically excluded in NFPA 99 6.7.6.2.1.5.

The net effect was that health care facilities were compelled to comply with NEC 700.10(D), regardless of the exclusion listed in NFPA 99, as AHJs enforced the direct requirements of the NEC and no one enforced the exclusions of NFPA 99. In the 2020 NEC, Section 700.10(D) no longer references health care facilities and 700.10(D) is specifically excluded in Article 517 and the situation is clear — life safety branch feeders are not required to be fire rated in the 2020 NEC.

New, deleted articles

Article 280, surge arresters, over 1,000 volts and Article 285, surge-protective devices, 1,000 volts or less, were combined and relocated to new Article 242, overvoltage protection.

Article 310, conductors for general wiring, was separated into two articles, with requirements for conductors rated 1,000 volts and below remaining in Article 310 and those for conductors rated 1,001 volts to 35 kilovolts moving to new Article 311, medium-voltage conductors and cable, together with requirements from Article 328, medium-voltage cable: type MV.

New Article 805, communications circuits, contains requirements of the former Article 800 and a new Article 800, general requirements for communication systems, captures information previously in Articles 820, 830 and 840, along with common requirements from the previous Article 800.

Article 553, floating buildings, was deleted and its provisions were relocated to Article 555, marinas, boatyards, floating buildings and commercial and noncommercial docking facilities.

Article 337, type P cable, was added to provide requirements for type P cable, generally suited to petrochemical and oil and gas drilling applications.

Section 90.2(A)(5) and (6)

Two items were added to the scope of the NEC, in Section 90.2(A)(5) and 90.2(A)(6). The extension of the scope of the code is a fairly rare event. No additions, other than the occasional inclusion of a fine-print note, appear in any of the editions going back to at least 1999.

Section 90.2(A)(5) adds shore power installations for marinas and boatyards to the scope of the code. Installations in watercraft themselves are excluded from the scope in Section 90.2(B)(1), leading AHJs and designers to consider shore power installations outside the scope as well. The new section was added to clarify that the shore power installation falls under the code, in response to electric shock injuries and drownings due to leakage currents in the water at marine facilities.

Section 90.2(A)(6) adds installations that support delivering power from electric vehicles to premises wiring. Typically, these will be bidirectional charging stations, with the ability to deliver energy to a connected vehicle from the power system and to deliver stored power from the vehicle to the premises wiring or eventually to the utility grid. The installed base of these devices in the United States is currently very small and most of the existing installations are experimental.

However, electric utilities, municipalities, transmission organizations and other organizations perceive a potential future benefit from using the electric vehicle fleet as a stored energy source for grid stabilization or for supplementing intermittent renewable energy sources to avoid resorting to fossil fuels for that purpose. The economics of vehicle-to-grid operation are not well-understood and It remains to be seen whether this technology will ever be widely accepted.


Tom Divine, PE, LEED AP
Author Bio: Tom Divine is a senior electrical engineer at Johnston, LLC. He is a member of the Consulting-Specifying Engineer editorial advisory board.