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NEC 2014 Enphase System Code Compliance © 2015 Enphase Energy Inc. All rights reserved. January 20153 capable of supplying multiple branch circuits or feeders, or both, the interconnecting provisions for the utility-interactive inverter(s) shall comply with 705.12(D)(1) through (D)(6). 705.12 (D) (4) Suitable for Backfeed. Circuit breakers, if backfed, shall be suitable for such operation. 705.12(D)(6) Wire Harness and Exposed Cable Arc-Fault Protection. A utility-interactive inverter(s) that has a wire harness or cable output circuit rated 240 V, 30 amperes, or less, that is not installed within an enclosed raceway, shall be provided with listed ac AFCI protection. This NEC 2014 code section allows connection of an electric power source to the load side of service disconnect means and requires that the interconnecting provisions for the utility-interactive inverter(s) shall comply with 705.12(D)(1) through (D)(6). Since the Enphase system contains one or more microinverters, which are the utility-interactive inverter(s), this section applies when connecting a system to the load side of a service disconnecting means. 705.12(D)(6) specifically requires that exposed AC cable systems, such as the Enphase Engage Cable, which is not feasibly run in enclosed raceway, to be protected by listed AC Arc-Fault Circuit Interrupter (AC AFCI) functionality. Given that utility-interactive inverters cannot operate without a utility service source, the location of the AC AFCI protecting the cable must logically be applied at the utility source side of the circuit. AC AFCI circuit breakers are the commonly available devices for single-phase branch circuits. No suitable for backfeed AC AFCI circuit breakers exist. Since Enphase Microinverters are utility-interactive inverters that backfeed into the electrical service through the overcurrent protection device, any AC AFCI circuit breakers must be specifically backfeed capable, per 705.12(D)(4). If terminals of circuit breaker AFCIs are marked Line and Load, then the AFCI product is not backfeed capable. No UL standard for backfeed testing exists for AC AFCI circuit breakers. Furthermore, 705.12(D)(6) requires that ac AFCI protection must be listed. For a product or product category to become listed, a standard safety test procedure, such as a UL standard, must exist. The testing standard for AFCI circuit breakers is UL1699, which currently does not have provisions for testing this product category for backfeed applications. It is clear, that the code requirement is ahead of new product availability. Summary Until suitable for backfeed and listed AC AFCI circuit breakers become generally available, an AHJ is permitted to refer to 90.4, i.e., the previous code edition, NEC 2011. Code Reference 90.4 Enforcement. This Code may require new products, constructions, or materials that may not yet be available at the time the Code is adopted. In such event, the authority having jurisdiction may permit the use of the products, constructions, or materials that comply with the most recent previous edition of this Code adopted by the jurisdiction. 1338 N Custer St 05/01/23