How long must an emergency generator provide power in case of fire?

An emergency generator in a high-rise building must provide power for a minimum of eight hours in the event of a fire or other emergency situations. This requirement is established to ensure that essential systems remain operational for a sufficient duration to facilitate safe evacuation and ongoing fire safety measures. During a fire, it is critical that emergency lighting, fire alarms, and other life safety systems function continuously, allowing occupants and first responders to navigate the building safely and effectively. The eight-hour requirement is set to accommodate potential delays in the response time of emergency services, ensuring that systems remain active until an alternative power source can be secured or the emergency is resolved.