What is the minimum continuous display time required for textual visible appliances during an emergency after primary power loss?

The minimum continuous display time for textual visible appliances during an emergency is set at 2 hours after primary power loss. This requirement is critical for ensuring that emergency information remains visible for a sufficient duration, allowing occupants and responders to receive essential guidance during a crisis. The two-hour display time allows for an effective response and evacuation process, ensuring that the visual alerts remain operational even when the building's main power supply has failed. This standard is designed to provide adequate time for individuals to act on the information provided by the visible appliances, which can include vital instructions or directional cues needed for safety. Keeping this display active for 2 hours ensures compliance with safety regulations, and it reflects best practices in life safety systems.