Fire alarm systems monitored by a central station are required to be connected to how many telephone lines?

Fire alarm systems monitored by a central station are required to be connected to how many telephone lines?

• A. Two
• B. One
• C. Three
• D. Four

Answer: (A)

The main idea is redundancy. Fire alarm systems that are monitored by a central station are required to have two separate telephone lines so that a signal can still reach the central station even if the first line fails. The primary line carries the alarm communication, while the secondary line serves as a backup path. If one line is out due to a fault, maintenance, or a disruption on that route, the second line still ensures the central station is notified. Using two lines greatly reduces the risk of a missed alarm compared to relying on a single line. Three or four lines would exceed the standard requirement for basic central-station monitoring, and a single line doesn’t provide any backup if that line fails. In practice, a system may also use a non-telephone backup (like cellular or radio) in addition to the two telephone lines, but the question specifically focuses on telephone lines, where two are required.

The main idea is redundancy. Fire alarm systems that are monitored by a central station are required to have two separate telephone lines so that a signal can still reach the central station even if the first line fails. The primary line carries the alarm communication, while the secondary line serves as a backup path. If one line is out due to a fault, maintenance, or a disruption on that route, the second line still ensures the central station is notified. Using two lines greatly reduces the risk of a missed alarm compared to relying on a single line.

Three or four lines would exceed the standard requirement for basic central-station monitoring, and a single line doesn’t provide any backup if that line fails. In practice, a system may also use a non-telephone backup (like cellular or radio) in addition to the two telephone lines, but the question specifically focuses on telephone lines, where two are required.