Under what condition can a luminaire be mounted directly to the ceiling without a junction box?

A luminaire can be mounted directly to the ceiling without a junction box when it is specifically listed for that type of installation. This means that the manufacturer has tested and certified the luminaire to safely and effectively be mounted in this manner. The electrical code allows for such exceptions to accommodate various design needs and installation practices, emphasizing the importance of adhering to the manufacturer’s specifications and safety standards.

The other conditions mentioned do not inherently allow for a luminaire to be mounted without a junction box. For instance, the material of the ceiling, like concrete, does not affect the requirement for a junction box unless the luminaire is also specifically listed for that installation. The location characteristics, such as being a damp area, require a compatible type of fixture and potentially more robust protective measures but do not eliminate the need for a junction box unless explicitly stated. Lastly, the presence or absence of other devices in the ceiling does not influence the safety requirements set forth by the NEC regarding junction box usage.