shall have overcurrent devices located so as to provide overcurrent protection from all sources.
Exception: An overcurrent device shall not be required for circuit conductors sized in accordance with
705.60(B) and located where one of the following applies:
(1) There are no external sources such as parallel- connected source circuits, batteries, or backfeed from inverters.
(2) The short-circuit currents from all sources do not ex- ceed the ampacity of the conductors.
FPN: Possible backfeed of current from any source of supply, including a supply through an inverter into the inverter output circuit and inverter source circuits, is a consideration in determining whether adequate overcurrent protection from all sources is provided for conductors and modules.
(B) Power Transformers. Overcurrent protection for a transformer with a source(s) on each side shall be provided in accordance with 450.3 by considering first one side of the transformer, then the other side of the transformer, as the primary.
Exception: A power transformer with a current rating on the side connected toward the inverter power source not less than the short-circuit output current rating of the inverter shall be permitted without overcurrent protection from that source.
(C) Inverter Source Circuits. Branch-circuit or supplementary-type overcurrent devices shall be permitted to provide overcurrent protection in inverter source circuits. The overcurrent devices shall be accessible but shall not be required to be readily accessible. Standard values of supplementary overcurrent devices allowed by this section shall be in one ampere size increments, starting at 1 ampere up to and including 15 amperes. Higher standard values above 15 amperes for supplementary over-current devices shall be based on the standard sizes provided in
240.6(A).
(D) Direct-Current Rating. Overcurrent devices, either fuses or circuit breakers, used in any dc portion of a utility interactive inverter power system shall be listed for use in dc circuits and shall have the appropriate voltage, current, and interrupt ratings.
(E) Series Overcurrent Protection. In series-connected strings of two or more modules, a single overcurrent protection device shall be permitted.
705.70 Utility-Interactive Inverters Mounted in Not- Readily-Accessible Locations. Utility-interactive inverters shall be permitted to be mounted on roofs or other exterior areas that are not readily accessible. These installations shall comply with (1) through (4):
(1) A direct-current disconnecting means shall be mounted within sight of or in the inverter.
(2) An alternating-current disconnecting means shall be mounted within sight of or in the inverter.
(3) An additional alternating-current disconnecting means for the inverter shall comply with 705.22.
(4) A plaque shall be installed in accordance with
705.10.