What does it mean to backfeed a panel, and when is it used?

• A. Supplying power to a panel from a source other than the normal service, without interlocks or interconnection.
• B. Backfeeding is the practice of feeding power back into the utility grid from the main service.
• C. Supplying power to a panel from a source other than the normal service, with proper interlocks or interconnection, is backfeeding.
• D. Backfeeding is allowed anytime without interconnections.

Answer: (C)

Backfeeding a panel means feeding power into a panel from a source other than the normal utility service (such as a generator or inverter) and doing so only with a proper interlock or interconnection that isolates the panel from the utility when the alternate source is energized. This setup is used to provide temporary or emergency power during an outage, using a transfer switch or a listed interlock to prevent any backflow of power onto the utility lines. The interlock ensures the main service disconnect and the alternate source cannot be energized at the same time, protecting lineworkers and equipment. Without interconnections, backfeeding can be dangerous and is not allowed, and simply attempting to feed a panel from another source without proper interconnection could energize the grid or the wrong parts of the panel.