Stand-Alone Systems

710.1 Scope. This article covers electric power production sources operating in stand-alone mode.



710.6 Equipment Approval. All equipment shall be listed or field labeled for the intended use.

710.15 General. Premises wiring systems shall be adequate to meet the requirements of this Code for similar installations supplied by a feeder or service. The wiring on the supply side of the building or structure disconnecting means shall comply with the requirements of this Code, except as modified by 710.15(A) through (F).

  1. Supply Output. Power supply to premises wiring systems shall be permitted to have less capacity than the calculated load. The capacity of the stand-alone supply shall be equal to or greater than the load posed by the largest single utilization equipment connected to the system. Calculated general light‐ ing loads shall not be considered as a single load.
  2. Sizing and Protection. The circuit conductors between a stand-alone source and a building or structure disconnecting means shall be sized based on the sum of the output ratings of the stand-alone sources.
  3. Single 120-Volt Supply. Stand-alone systems shall be permitted to supply 120 volts to single-phase, 3-wire, 120/240-volt service equipment or distribution panels where there are no 240-volt outlets and where there are no multiwire branch circuits. In all installations, the sum of the ratings of the power sources shall be less than the rating of the neutral bus in the service equipment. This equipment shall be marked with the following words or equivalent:WARNING:SINGLE 120-VOLT SUPPLY. DO NOT CONNECT MULTI‐ WIRE BRANCH CIRCUITS!The warning sign(s) or label(s) shall comply with 110.21(B).
  4. Energy Storage or Backup Power System Requirements.Energy storage or backup power supplies are not required.
  5. Back-Fed Circuit Breakers. Plug-in type back-fed circuit breakers connected to an interconnected supply shall be secured in accordance with 408.36(D). Circuit breakers marked “line” and “load” shall not be back-fed.