What is a common feature of a two-stage fire alarm system?

A common feature of a two-stage fire alarm system is that it requires confirmation before alerting emergency services. In this type of system, the first stage typically involves the detection of smoke or heat, which activates an initial alarm that alerts occupants to the potential danger. However, before emergency services are contacted, there is a built-in mechanism that allows for verification of the alarm. This helps to prevent false alarms and ensures that emergency services are only notified when there is a genuine need for their intervention.

The requirement for confirmation can involve checking the situation to ascertain whether there is indeed a fire or simply a false alarm caused by environmental factors. This two-step process enhances the reliability of fire response systems and minimizes unnecessary emergency service responses, leading to more effective use of resources.

While other options may relate to fire alarm systems in some capacity, they do not define the characteristic of a two-stage fire alarm specifically. Triggering an evacuation, activating a manual call point, or interlocking with a sprinkler system are functionalities that may or may not be present in such systems, but confirmation before notifying emergency services is a defining feature that distinguishes the two-stage approach.