This article focuses on revisions in Chapter 7, “Special Conditions,” which includes the requirements for conditions such as emergency systems, energy storage systems and so forth, and Chapter 8, “Communications Circuits.”
Sections 700.4 and 701.4 Capacity and Rating
Requirements for capacity rating in 700.4 and 701.4 are correlated for clarity and to address how the system capacity is to be determined. As revised, sections 700.4(B) and 701.4(B) now permit capacity to be determined by Article 220 or another approved method. Section 701.4(C), “Load Pick Up, Load Shedding, and Peak Load Shaving,” now correlates with requirements in 700.4.
Sections 700.5, 701.5 and 702.5 Transfer Equipment
Meter-mounted transfer switches are prohibited for use in emergency and legally required systems. These switches are permitted for use only in optional standby systems. Section 702.5 is significantly revised and separated into five first-level subdivisions. This equipment is required to be listed by a qualified electrical testing laboratory and must have the authority having jurisdiction’s approval, which could also include the serving utility.
Section 700.12(H) DC Microgrids
Section 700.12(H) has been incorporated to recognize sources connected to a DC microgrid system. DC microgrids used as emergency systems must to be capable of being isolated from all nonemergency sources and must be of suitable rating and capacity to supply and maintain the total emergency load for not less than two hours at full demand. Where a DC microgrid system is the normal supply for the building, it shall not serve as the sole source of power for the emergency system.
Sections 700.23 and 700.24 Dimmer and Relay Systems/Directly Controlled Emergency Luminaires
Emergency dimmers or relay systems may obtain a normal power-sensing function from a normal-only power source upstream of the transfer switch. Directly controlled emergency luminaires may respond to an external control input, or loss thereof, to bypass normal control upon loss of normal power.
Sections 700.32, 701.32 and 708.54 Selective Coordination
Selective coordination is the localization of an overcurrent condition to restrict outages to the local circuit or equipment affected. New informational notes (IN) and figures are added in 700.32, 701.32 and 708.54 for selective coordination. Essential clarification has been provided for Code users to assist in the determination of which overcurrent protective devices must selectively coordinate. The new IN figures provide guidance in the application of these requirements.
Section 705.13 Power Control Systems
New Section 705.13 provides requirements for power control systems (PCS). These systems are necessary where multiple energy sources and/or energy storage systems (ESS) exist on the premises. The PCS monitors all currents to ensure that an overload does not occur, and it may be listed as an overcurrent protective device.
Sections 706.3, 706.7 and 706.8 Qualified Persons, Maintenance and Storage Batteries
New Section 706.3 requires that the installation and maintenance of all ESS equipment, wiring and connections be performed by qualified persons only. The term “qualified person” is defined in Article 100 of the NEC. Section 706.7 is new and requires all ESS to be maintained in proper and safe operating conditions. New Section 706.8 requires storage batteries that are not associated with an ESS be installed in accordance with Article 480.
Section 706.15 Disconnecting Means
The required disconnecting means is permitted to be integral to the ESS. A disconnect or remote control must be installed outdoors in a readily accessible location for one- and two-family dwelling units. Disconnects require an arc flash label applied in accordance with acceptable industry practice.
Section 725.144 Transmission of Power and Data
Section 725.144, “Transmission of Power and Data,” has been revised for improved clarity. IN No. 2 has been revised to provide additional information on connectors for electronic equipment. New IN No. 3 explains that the requirements of Table 725.144 were derived for carrying power and data over four-pair copper balanced twisted-pair cabling. New IN No. 4 references guidelines for supporting power delivery over balanced twisted-pair cabling. The new IN No. 5 references a standard for lighting systems and power over ethernet. Based on data provided in a fact-finding report, the values in Table 725.144 are modified and rounded to two decimal places.
Article 800 General Requirements for Communications Systems
New Article 800 contains general requirements for all Chapter 8 articles, which removes redundancies and improves the usability of the Code. Section 800.3 requires reconditioned equipment under the purview of Chapter 8 must comply with the requirements of 110.21(A)(2).