There are a few more changes in Chapter 6 to discuss before we move into Chapter 7.
690.15 Disconnecting Means for Isolating PV Equipment. Section 690.15(D), Type of Disconnecting Means, has been relocated to 690.15(A). Revised wording clarifies that disconnecting means complying with 690.15(C) are permitted in any circuit, regardless of current rating. Section 690.15(A)(2) will now permit an isolating device that is part of listed equipment where an interlock prevents opening the isolating switch under load. Section 690.15(D) was rewritten to remove the distances and to replace them with the terms “readily accessible” and “in sight from.” Requirements for what is considered “in sight from” are found in new Section 110.29.
690.31 Wiring Methods. Section 690.31(A)(2) has been expanded to cover requirements for wiring that is not guarded. Where photovoltaic (PV) system DC conductors operating at greater than 30V are readily accessible to unqualified persons, installation in MC cable, multiconductor jacketed cable or raceway is required. The list of wiring methods aligns with 690.31(C). A new 690.31(B)(1) has been added for conductors of different systems that establishes which conductors can be intermingled. Section 690.31(B)(3) was revised to clarify that it applies to AC and DC conductors, and that they must be grouped separately by cable ties or similar means at least once and at 6-foot intervals.
691.1 and 691.4 Large-Scale Photovoltaic (PV) Electric Supply Stations. Large-scale PV systems are those that have an inverter generating capacity of 5,000 kilowatts (kW) or larger not under exclusive utility control. The 5,000-kW lower limit was moved from the scope to 691.4(7) because the NEC Style Manual does not permit requirements to be in an article scope statement. Section 691.4(6) now requires large-scale PV systems to be monitored from a central command center.
Article 692 Fuel Cell Systems. Article 692 applies to the installation of fuel cells. It was modified to simplify the article and to delete redundant material. The renewable energy articles all depend on the requirements of Article 705, Interconnected Electric Power Production Sources.
There has been an effort during this cycle to remove redundant requirements in articles, such as 690, 692 and 694, and to rely more on the requirements in articles 705 and 706. For example, the requirements for identification of power sources were consolidated in 705.10. Section 90.3 indicates that the requirements of chapters 1 through 4 apply generally and that the requirements of chapters 5, 6 and 7 can modify the requirements of earlier chapters. The requirements in Article 692, Part V, did not modify those of Article 250, and were therefore deleted. Since fuel cells are required to be listed, requirements in this article that would be part of a listing evaluation were deleted.
694.50 and 694.68 Interactive System Point of Interconnection. The marking requirement in 694.50 for interactive points of interconnection with other sources was deleted. The new requirement is 705.14, which is a more general requirement for labeling an interactive point of connection to other sources. The requirement for points of connection was deleted from 694.68. The intent is that interconnected sources comply with Article 705 and they are not repeated in each article covering another source.
695.1(B) Not Covered. Article 695 provides requirements for electric fire pumps, including sources, switching and controls. The need for a fire or a water pump depends on several factors, including the adequacy of the water supply for providing sufficient fire protection for the home’s type and size.
The need for a water or fire pump would be indicated by the applicable fire protection standard. For most one- and two-family dwellings, NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, would apply. This change makes it clear that Article 695 would not apply to water pumps in such homes. For larger homes, NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies, or NFPA 13, Standard for the Installation of Sprinkler Systems, may apply. A fire pump in a larger home would be required to comply with Article 695.
695.7 Voltage Drop. Section 695.7 was revised to update the extracted text from NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection. The technical requirements for this extracted text are the responsibility of the Technical Committee on Fire Pumps. The NEC extracts the text from the source document, but can change the text only to the extent necessary to make it part of the Code. The requirement in 695.7(A) does not permit the voltage drop to exceed 15% under motor starting conditions. The newly recognized emergency run mode and bypass mode are permitted to exceed the 15% limit on voltage drop if the fire pump can be started while it is being supplied by the standby generator.
700.3 Tests and Maintenance. The title of 700.3(A) was revised from “Conduct or Witness Test” to “Commissioning Witness Test” to make it clear that emergency systems should be commissioned prior to being placed in service. Section 700.3(F) provides requirements for the use of a temporary source of power when an emergency power source must be out of service for maintenance or repair of the prime mover. Some emergency power supplies consist of multiple generators, but many do not. The requirements in (F) apply where there is a single emergency power supply. The new requirements call for listed switching means to allow the connection of a temporary source, including mechanical or electrical interlocks, that prevent inadvertent interconnection of power sources. Inadvertent interconnection of sources could cause damage to equipment and injuries to maintenance personnel.
The connection point is required to be a permanent one that is located outdoors. Wiring for temporary sources is not permitted to be run through windows or doors. Field-applied labels are required at the connection point to provide information to those making the interconnection.
Section 700.4(B), now titled “Selective Load Management,” was revised to recognize that emergency systems may have variable loads, including motor starting, which must be considered when determining the necessary capacity of the system.
700.4 Capacity and Rating. Section 700.4(A), which required the emergency system to be suitable for the available fault current at its terminals, was deleted because it is already covered in 110.9 and 110.10. As a result, 700.4(B) became (A). This was part of the initiative to eliminate redundant requirements. Section 700.4(B), now titled “Selective Load Management,” was revised to recognize that emergency systems may have variable loads, including motor starting, which must be considered when determining the necessary capacity of the system. A similar requirement has been added to 701.4(C) for legally required standby systems.
Peak load shaving is now covered in the new 700.4(C) on parallel operation. There are two types of parallel operation recognized in 700.4(C). The first type is where an emergency source is operated in parallel with the normal source. A typical use case is peak load shaving. The second type of parallel operation consists of multiple emergency sources operated in parallel. The same changes were made in 701.4(C) and (D) for legally required standby systems.
700.5 Transfer Equipment. The requirement in 700.5(A) for AHJ approval of transfer switches was deleted because approval is already required for all electrical equipment in 110.2. The prohibition of reconditioning transfer equipment still exists, but it was moved into a new Section 700.2.
If emergency loads are served by a single automatic transfer switch, 700.5(D) requires that there be redundant transfer equipment or a bypass isolation switch to facilitate maintenance without jeopardizing power continuity. If the redundant transfer equipment or bypass isolation switch is not automatic, the redundant transfer switch or bypass isolation switch must be supervised by a qualified person when the primary transfer switch is out of service. An exception recognizes four conditions under which the redundancy with the transfer equipment may be omitted.
About The Author
EARLEY, P.E., is an electrical engineer. Retired from the National Fire Protection Association, he was secretary of the National Electrical Code Committee for 30 years and is president of Alumni Code Consulting Group.