Which condition is critical for luminaires used in emergency systems?

Luminaires used in emergency systems must comply with specific NEC guidelines to ensure safety, reliability, and effectiveness during emergency situations. The National Electrical Code outlines standards that govern the installation, operation, and maintenance of electrical equipment, including emergency lighting. These guidelines help to ensure that emergency luminaires function appropriately during power outages or emergencies, providing adequate illumination for safe egress. Compliance with NEC standards ensures that the luminaires meet structural, electrical, and performance criteria necessary to function as intended when needed most.

While other options may seem relevant, such as the need for battery backup or specific features, compliance with NEC guidelines is the foundational aspect that allows emergency luminaires to serve their critical role effectively.