Under what condition are replacement luminaires exempt from connecting to an equipment grounding conductor?

Replacement luminaires are exempt from connecting to an equipment grounding conductor when the outlet box has no grounding conductor. This is a recognition of practical construction situations where an existing structure may not have been built with a grounding system in place. In such cases, if an outlet box does not provide a grounding conductor, it would be unsafe and impractical to require a new luminaire to be grounded.

The NEC allows for specific exemptions under these circumstances to ensure that lighting installations can be performed without compromising safety or violating code requirements. This provision helps facilitate the replacement of fixtures in older buildings and non-grounded installations while still prioritizing safety.

The other conditions described do not provide valid exemptions under the NEC. For example, larger luminaires may present additional issues regarding installation but do not influence grounding requirements. Similarly, whether a luminaire is GFCI protected does not negate the need for grounding if it is required. Finally, temporary luminaires typically have different requirements dictated by their nature, and their grounding must be considered separately in accordance with temporary power guidelines.