The sign illumination means must ensure continued illumination for at least how many minutes during primary power loss?

The requirement for sign illumination to ensure continued lighting during a primary power loss is vital for safety and visibility, especially in emergency situations. In this context, maintaining illumination for at least 90 minutes ensures that signs remain visible during power outages, allowing for safe egress from a building or space. This duration is particularly important for exit signs and safety-related signage in commercial buildings, as it complies with safety regulations aligned with the National Fire Protection Association (NFPA) guidelines and other related codes. These requirements are designed to provide sufficient time for evacuation and to guide occupants safely in low visibility conditions.

While other durations such as 30, 60, or 120 minutes may be considered for different types of lighting or codes, the specific requirement of 90 minutes has been established as a standard in many regulatory frameworks to enhance safety in commercial settings.