After losing primary power, how long must textual visible appliances operate on secondary power during an emergency?

The requirement for textual visible appliances to operate on secondary power during an emergency is designed to ensure adequate visibility for safety and evacuation purposes. This typically aligns with the standards set forth by the National Fire Protection Association (NFPA) and other relevant codes.

In many jurisdictions, a two-hour operational period on secondary power is mandated for such appliances. This duration provides a sufficient buffer for individuals to safely evacuate a building or find safe areas during an emergency. It balances the need for reliable visibility with realistic battery life for emergency systems, allowing for continuous operation even when primary power is lost.

The two-hour timeframe also reflects the necessity for appliances to be functional not only during initial emergencies but also during potential follow-up scenarios, such as delays in restoring primary power or additional emergencies that may arise shortly thereafter. Such standards enhance the overall safety of fire alarm systems and ensure compliance with protective measures for building occupants.