Changes in and additions to the NFPA 70

Changes in and additions to the NFPA 70: National Electrical Code (NEC) have a significant impact on commercial and industrial facilities.

Learning objectives:

Outline NFPA 70: National Electrical Code (NEC).

Analyze the updates and changes to the most recent edition of the NEC.

Compare and contrast each of the new items in NFPA 70-2014.

Every 3 yr, NFPA 70-2014: National Electrical Code (NEC) is updated and released. However, not all states immediately adopt the new code changes. The adoption by many states doesn't typically occur until the year after the latest version is released.

According to NFPA, there were 3,745 proposals submitted recommending changes to the 2014 edition of the NEC. In addition, there were 1,625 comments concerning the NEC Code-Making Panels' responses to these proposals.

Overall impact of code changes

There are several new articles as well as some noteworthy changes included in the 2014 edition of the NEC. Some changes have had a significant impact on the electrical trade. An example is a codewide change to raise the maximum voltage level from 600 V to more than 1,000 V, primarily driven by the higher voltages in wind turbine and photovoltaic (PV) systems. The voltage increase affects numerous articles including 240, 250, 300, 430, 490, 690, 692, and 694.

While many of these changes are purely editorial in nature, the change in the transformer protection table, Table 450.3(A), compels system designers to use smaller overcurrent-protective devices (OCPDs) for protecting transformer primaries when within the 600 V-to-1,000 V range. Although there are no standard operating voltages within this range, this predominantly affects renewable energy sources, which can connect at voltages not commonly seen in standard distribution. It should also be noted that this reduction in OCPD sizing facilitates in the mitigation of arc flash hazards, which have been in the spotlight for safety awareness and recent code changes. Transformers are typically a location of elevated incident-energy levels, and faster OCPD tripping can reduce incident-energy levels.

Impact on commercial and industrial facilities

Some of the code additions and modifications have substantial impact on commercial and industrial facilities. The following list describes, in sequence, seven changes in NEC 2014 that have a high impact on commercial and industrial systems:

  1. Dedicated equipment space

  2. Ground-fault protection (GFP)

  3. Conductor sizing

  4. Arc energy reduction

  5. Surge protection

  6. Selective coordination requirements and health care

  7. Solar system rapid-shutdown systems.

Dedicated equipment space

NEC 2014 change

Article 110: Requirements for Electrical Installations; Section 110.26(E) Dedicated Equipment Space, (2). Outdoor:

Outdoor installations shall comply with 110.26(E)(2)(a) and (b).

Subsection (b), Dedicated Equipment Space: The space equal to the width and depth of the equipment and extending from grade to a height of 1.8 m (6 ft) above the equipment shall be dedicated to the electrical installation. No piping or other equipment foreign to the electrical installation shall be located in this zone.

Analysis of changeAs with indoor equipment, dedicated space is now required for installation of outdoor equipment (see Figure 1). This is clarified in the code to pertain to all switchboards, switchgear, panelboards, and motor control centers. This removes the gray area of interpretation and clarifies the issue for design engineers, contractors, and the authorities having jurisdiction.