Which of the following conditions applies to outlet boxes that are to support ceiling-suspended paddle fans?

The correct condition that applies to outlet boxes supporting ceiling-suspended paddle fans is that these boxes must be listed for support. This requirement is critical because ceiling fans can exert significant downward forces, and it is essential that any outlet box used is specifically designed and listed to handle the weight and forces associated with such installations. When an outlet box is listed for support, it has been tested and approved to ensure that it can safely hold the fan and withstand operational vibrations, which is crucial for both safety and functionality.

In contrast, while other options may address various aspects of installation or product specifications, they do not specifically pertain to the structural integrity and safety requirements mandated by the NEC for ceiling fan support. For instance, securing an outlet box with three screws could be relevant for stability but does not guarantee the box is rated for the loads imposed by a ceiling fan. Similarly, while double gasket seals and paint color might be relevant for environmental protection or aesthetics, they have no bearing on the outlet box's capacity to support a ceiling fan safely. Therefore, the emphasis on a box being listed for support best aligns with the NEC's focus on safety and compliance in electrical installations.