What causes signals to be sent in heat detectors?

Prepare for the First Responder Inspector Test. Utilize sample tests, detailed explanations, and interactive flashcards to boost your confidence and knowledge. Get exam-ready!

Heat detectors send their signal by changing the electrical state of the circuit they’re in. When heat is detected, the internal switch inside the detector flips, and that change can be either opening the circuit or closing it, depending on how the detector is designed. Some detectors are normally closed and open on activation; others are normally open and close on activation. The fire alarm panel monitors this state change to trigger an alarm. Water flowing through a sprinkler isn’t what causes a heat detector to signal, since heat detectors respond to temperature changes, not water flow. That’s why the best answer recognizes that signals can come from either opening or closing, depending on the detector’s design.