no smaller than 14 AWG.
(B) Ground-Fault Protection Not Provided. For other than dwelling units where ground-fault protection is not provided in accordance with 690.5(A) through (C), each equipment grounding conductor shall have an ampacity of at least two (2) times the temperature and conduit fill corrected circuit conductor ampacity.
FPN: The short-circuit current of photovoltaic modules and photovoltaic sources is just slightly above the full-load normal output rating. In ground-fault conditions, these sources are not able to supply the high levels of short- circuit or ground-fault currents necessary to quickly activate overcurrent devices as in typical ac systems. Protection for equipment grounding conductors in photovoltaic systems that are not provided with ground-fault protection is related to size and withstand capability of the equipment grounding conductor, rather than overcurrent device operation.
690.46 Array Equipment Grounding Conductors.
Equipment grounding conductors for photovoltaic modules smaller than 6 AWG shall comply with 250.120(C).
690.47 Grounding Electrode System.
(A) Alternating-Current Systems. If installing an ac system, a grounding electrode system shall be provided in accordance with 250.50 through 250.60. The grounding electrode conductor shall be installed in accordance with
250.64.
(B) Direct-Current Systems. If installing a dc system, a grounding electrode system shall be provided in accordance with 250.166 for grounded systems or 250.169 for un- grounded systems. The grounding electrode conductor shall be installed in accordance with 250.64.
Systems with Alternating-Current and Direct-Current
Grounding Requirements. Systems with alternating- current and direct-current grounding requirements shall comply with items (C)(1) through (C)(8):
(1) Where photovoltaic power systems have both alternating-current (ac) and direct-current (dc) grounding requirements, the dc grounding system shall be bonded to the ac grounding system.
(2) A bonding conductor between these systems shall be sized as the larger of the dc requirement in accordance with 690.45, the ac requirements based on the inverter alternating current overcurrent device rating and
250.122, and the system bonding requirements of
250.28.
(3) A conductor that serves as both an equipment grounding conductor and as part of the bond between ac and dc systems for an inverter incorporating dc ground-fault protection shall meet the requirements for equipment bonding jumpers in accordance with 250.102 but shall not be subject to the requirements for bonding jumpers in accordance with 250.28. A single conductor shall be permitted to be used to perform the multiple functions of dc grounding, ac grounding, and bonding between ac and dc systems.
(4) A bonding conductor or equipment grounding conductor that serves multiple inverters shall be sized based on the sum of applicable maximum currents used in item (2).
(5) A common ground bus shall be permitted to be used for both systems.
(6) A common grounding electrode shall be permitted to be used for both systems, in which case the grounding electrode conductor shall be connected to the ac ground system bonding point
(7) Grounding electrode conductors) shall be sized to meet the requirements of both 250.66 (ac system) and
250.166 (dc system).
(8) For systems with utility-interactive inverters, the pre- mises grounding system serves as the ac grounding system.