Which signal type indicates an off-normal condition in a fire alarm system?

The signal type that indicates an off-normal condition in a fire alarm system is supervisory. This type of signal is specifically designed to monitor the integrity and functionality of the fire alarm system components. When a supervisory signal is activated, it means that there is a condition present that could impair the proper functioning of the fire protection system.

Supervisory signals typically relate to conditions such as the tampering of equipment, malfunction of components, or issues such as valve positions in sprinkler systems. These alerts are crucial because they do not indicate a fire or emergency situation directly, but rather a potential problem that may affect the performance of the system during critical times.

In contrast, other signal types serve different purposes: alarm signals indicate the presence of a fire, trouble signals denote a failure within the system that doesn't directly impair its ability to alert (like a loss of power), and alert signals are not commonly recognized in the standard terminology of fire alarm systems. Understanding the role of supervisory signals helps in maintaining the overall reliability of fire safety systems, as they provide necessary information about operational issues that need to be addressed.