If primary power fails on a fire alarm system, what must happen within 30 seconds?

When primary power fails in a fire alarm system, it is crucial for the system to notify users of the status and functionality of the system. This is where the initiation and recording of a trouble signal comes into play. A trouble signal indicates that there is an issue with the primary power supply, which is vital for the ongoing safety and reliability of the fire alarm system.

While it is important for a fire alarm system to maintain power through a secondary power supply, the key action required within 30 seconds of power failure is to alert users or operators of the trouble condition. This means that the focus here is on communication and assurance that the system is aware of the failure and is still operational to some extent, even if running on backup power.

A secondary power supply indeed plays a critical role in keeping the system operational, preventing signals from being lost or delayed. However, without the signal being generated to indicate that there is a problem, the function of the backup power becomes irrelevant to users who need to know that an issue has occurred. Therefore, the initiation and recording of this trouble signal is the fundamental requirement in this scenario.