After loss of secondary power, within how many minutes must egress doors unlock?

• A. 5 minutes
• B. 10 minutes
• C. 15 minutes
• D. 20 minutes

Answer: (B)

When power to the building’s life-safety doors is lost, the doors must be able to be opened to allow occupants to exit without being trapped. The rule sets a ten-minute window for egress doors to unlock after a loss of secondary power. This time frame provides a practical safety margin: it ensures doors don’t remain locked during a power outage, while still allowing for the systems that manage emergency power, alarms, and initial evacuation actions to come online. In practice, door hardware is designed to release (or switch to a fail-safe mode) when power is removed, often coordinated with the fire alarm system so doors unlock automatically during an incident. Minutes shorter than ten could risk false activations or premature releases, while longer than ten could leave egress routes obstructed during the critical early moments of an emergency.