CODE CORNER: Rapid Shutdown

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The required label at the RS switch. These labels comply with NEC Section 690.56(C)(1) requirements for PV systems with rapid shutdown both inside and outside the array boundary. In jurisdictions that have adopted the 2017 NEC, this will be the only type of RS allowed after January 1, 2019.
This label must be located no more than 3 feet from the service-disconnecting means. These labels comply with NEC Section 690.56(C)(1) requirements for PV systems with rapid shutdown both inside and outside the array boundary. In jurisdictions that have adopted the 2017 NEC, this will be the only type of RS allowed after January 1, 2019.

Section 690.12 of the National Electrical Code (NEC), which was first introduced in 2014, governs rapid shutdown (RS) of PV systems on buildings. For the 2017 edition, this section has been expanded and clarified, including defining RS initiation devices. (See “New Rapid Shutdown Solutions” in this issue for more information on strategies and products to meet new RS requirements.)

Where RS Applies

Section 690.12 only applies to PV systems in or on buildings—ground- or pole-mounted systems are not subject to these requirements so long as none of the system circuits “touch” a building.  An exception is when a building’s sole purpose is to house PV system equipment; then RS does not apply.

Wiring from the PV and within the PV array to the PV system disconnect is subject to 690.12—see the system schematics in Figure 690.1(b) for specific configurations on page 47 of this issue. This is an example of how clearly defining the location of the PV system disconnect adds clarity throughout Article 690. For instance, this shows that an energy-storage system in an AC-coupled multimode system is not part of the PV system, and thus not subject to RS.

Newly defined in the 2017 edition, the PV array boundary is described as 1 foot in all directions from the outer edges of the PV array. Section 690.12(B)(1) applies to PV system circuits outside of the array boundary, as well as to circuit conductors more than 3 feet from the point of entry into the building; 690.12(B)(2) covers circuits inside of the array boundary. While the RS voltage limit is higher inside the array boundary, the requirement to control PV system conductors inside the array boundary has in practice necessitated module-level RS, which has tremendous implications on system design and component selection.

RS is not a disconnect requirement—rather, it resides in Part II of Article 690, “Circuit Requirements.” As such, a variety of products—some of which may be disconnects—can be used and must be listed for the purpose per Section 690.12(D). However, this requirement for listing does not include disconnects, circuit breakers, or control switches that are used to initiate rapid shutdown.

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