Codes and Standards
Overview of changes throughout NEC
Several changes were made to the 2017 edition of the National Electrical Code.
Figure 1: A primary current injection testing wiring diagram is shown. Courtesy: Arup
Some of the most notable changes impacting 2017 edition of NFPA 70: National Electrical Code are:
- All definitions that appeared in two or more articles have been relocated to Article 100.
- New requirements have been added for the use of calibrated tightening torque tools for electrical connections, where a torque value is indicated on equipment or listed in installation manual by the manufacturer.
- New labeling requirements, such as detailed arc flash hazard warning on equipment to help assess electrical risks, have been added per Section 110.16(B).
- New Section 110.21(A)(2) requires reconditioned equipment to be marked with the name, trademark or other descriptive marking, identifying the organization responsible for reconditioning the electrical equipment including the date of the reconditioning.
- New Section 110.26(A)(4) addresses access and space clearances required for equipment that by installation instructions or function is located in a “limited access location.”
- The migration from 600 volts to 1,000 volts that started with 2014 NEC continues, all relative to the current trends in the electrical industry. These changes have been primarily in response to renewable energy systems that operate over 600 volts and the NEC lacked requirements to safely cover these systems.
- New and revised provisions for arc-fault circuit interrupter and ground-fault circuit interrupter protection to improve electrical and fire safety at homes have been addressed per Sections 210.12 (C) and (D).
- New Section 210.11(C)(4) requires at least one 20-ampere rated branch circuit to supply dwelling unit garage 125-volt receptacle outlet(s).
- New Section 210.71 requires a minimum number of receptacles to be installed in meeting rooms not exceeding 1,000 square feet.
- Revisions made to the acceptable grounding electrode system for a separately derived system listed under Section 250.30(A)(4). The metal water piping and structural metal grounding electrodes are no longer mandatory and now any of the building or structure grounding electrodes described at Section 250.52(A) can be used as the grounding electrode for separately derived system. As a matter of fact, the water pipe and the structural metal frame per Section 250.68(C) are not considered grounding electrodes but rather are conductors extending the grounding electrode connection.
- Revisions made to Section 310.15(B)(3)(c) requires a minimum of 7/8 inch clearance from the roof surface for raceways and cables or else they will be subject to 60°F temperature adder. The old temperature adder table has been removed.
- Revisions made to Section 406.12 expand the list of spaces requiring the use of tamper-resistant 125- and 250-volt, nonlocking 15- and 20-ampere receptacles.
- New Section 422.6 requires that all appliances operating at 50 volts or more to be listed.
- All battery management equipment and batteries, except lead-acid, must be listed per Section 480.3.
- Electrical metallic tubing is no longer allowed for installation in Class 1, Division 2 areas per Section 501.10(B)(1).
- The surge protection device requirements have been expanded beyond emergency power systems to include protection for specific elevators, critical operations power systems and for industrial machinery per Sections 620.51(E), 645.18 and 670.6.
- New requirements added throughout the NEC involving the documentation of the available short-circuit current at specific types of equipment (e.g., motor control centers, air conditioning equipment, elevators, industrial machinery and industrial control panels) and the date the short-circuit current calculation was performed. The documentation for the calculation required for the short-circuit current marking must be made available to the owner and to anyone maintaining or operating the facility and more importantly to the authority having jurisdiction.
- The recent developments and growth in the renewable power systems generation and storage technologies have resulted to significant changes to the existing Article 690 along with addition of four new articles 691, 706, 710 and 712, all mentioned earlier.
- The short-circuit current rating of the transfer equipment, based on the specific overcurrent protective device type and settings protecting the transfer equipment, shall be field marked on the exterior of the transfer equipment per Sections 700.5(E), 701.5 (D) and 702.5.
- New Section 725.144 has been added to address requirements for types of Class 2 and 3 cables for transmission of data and power to connected devices. This is commonly referred to as power over Ethernet and is becoming very popular for many applications such as circuiting for LED lighting.