Ceiling-suspended (paddle) fans are required to be installed on:

Ceiling-suspended (paddle) fans are required to be installed on boxes marked as suitable for fan installation to ensure safety and structural integrity. These boxes are specifically designed to handle the weight and dynamic forces exerted by the movement of the fan. They are constructed to support the additional load that a fan places on the electrical box, which is significantly heavier than standard lighting fixtures.

Using a box that is marked as suitable for fan installation ensures compliance with electrical codes and standards, which are set to prevent accidents such as the improper support of the fan potentially leading to its falling or causing electrical hazards. This designation indicates that the box has been tested and approved for such applications, providing both the necessary strength and stability for the safe operation of ceiling fans.