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20.20.027 assembly, together with its over current device(s), that is listed for continuous operation at 100 per- cent of its rating shall be permit- ted to be utilized at 100 percent of its rating. (2) Internal Current Limitation. Over current protection for photovoltaic output circuits with devices that internally limit the current from the photovoltaic output circuit shall be permitted to be rated at less than the value computed in 690.8(B)(1). This reduced rating shall be at least 125 percent of the limited current value. Photovoltaic output circuit conduc- tors shall be sized in accordance with 690.8(B)(1). Exception: An over current device in an assembly listed for continuous operation at 100 percent of its rating shall be permitted to be utilized at 100 percent of its rating. (C) Systems with Multiple Direct- Current Voltages. For a photovoltaic power source that has multiple out- put circuit voltages and employs a common-return conductor, the ampacity of the common-return con- ductor shall not be less than the sum of the ampere ratings of the over current devices of the individual output circuits. (D) Sizing of Module Interconnec- tion Conductors. Where a single over current device is used to protect a set of two or more parallel-connected module circuits, the ampacity of each of the module interconnection con- ductors shall not be less than the sum of the rating of the single fuse plus 125 percent of the short-circuit cur- rent from the other parallel-connect- ed modules. 690.9 Over current Protection. (A) Circuits and Equipment. Photo- voltaic source circuit, photovoltaic output circuit, inverter output circuit, and storage battery circuit conductors and equipment shall be protected in accordance with the requirements of Article 240. Circuits connected to more than one electrical source shall have over current devices located so as to provide over current protection from all sources. Exception: An over current device shall not be required for circuit conductors sized in accordance with 690.8(B) and located where one of the following apply: (a) There are no external sourc- es such as parallel-connected source circuits, batteries, or back feed from inverters. (b) The short-circuit currents from all sources do not exceed the ampacity of the conductors. FPN: Possible back feed of cur- rent from any source of supply, including a supply through an inverter into the photovoltaic output circuit and photovoltaic source circuits, is a consideration in determining whether adequate over current protection from all sources is provided for conductors and modules. (Pleasanton April 2003) '] 10_2,