What could be a consequence of not using a listed and marked outlet box for fan support?

Using a listed and marked outlet box for fan support is crucial because it ensures the safety and structural integrity of the installation. When a fan is mounted, it exerts weight and vibrations, which can cause stress on the support structure. A listed and marked outlet box is specifically designed to handle these loads, complying with safety standards and building codes.

If a box that isn't rated or marked for fan support is used, it may not be able to withstand the weight and movement of the fan, leading to potential failure of the fan or even detachment from the ceiling. This could result in damage to both the fan and the surrounding area, and pose a safety risk to individuals below.

Thus, ensuring that the outlet box is appropriately listed and marked is essential for not only the longevity of the fan but also for maintaining overall safety in residential wiring applications.