What modification is prohibited by Article 410 when installing luminaires?

Article 410 of the National Electrical Code (NEC) emphasizes the importance of maintaining the safety and integrity of luminaires by adhering to their listing and manufacturer's specifications. When luminaires are modified in ways that could compromise their safety or original design, they may not function as intended, potentially leading to electrical hazards, fire risks, and violations of safety standards.

Modifying luminaires in ways that alter their intended use or design not only risks creating unsafe electrical conditions but can also void warranties and listings that are crucial for ensuring compliance with safety regulations. Keeping the modifications within the prescribed guidelines ensures that luminaires can operate safely and effectively, providing the intended illumination without risk.

Other actions, like replacing incandescent bulbs with LED bulbs or changing the color of the fixture, typically do not inherently compromise the luminaire's safety or its listing, provided these replacements are made according to the manufacturer's guidelines. Adjusting the height of overhead luminaires, when done following local codes and manufacturer specifications, can also be permissible and does not usually present a safety issue. Thus, the prohibition centers specifically on modifications that undermine safety or listed design, which is why this answer is recognized as correct.