Which of the following is a likely cause of a repeated fault on an alarm phone line?

• A. Ground start malfunction
• B. Faulty modem
• C. Cable shield fault
• D. Improper termination

Answer: (A)

Ground start signaling relies on pulling the line to ground to seize the telephone circuit for dialing. If the grounding path has a fault—such as a loose connection, moisture, or a compromised ground—every time the panel tries to use the line it detects an abnormal condition and flags a fault. This makes a ground start malfunction a common cause of repeated faults on an alarm phone line, because the issue is tied to how the line is being activated and held in use.

A faulty modem would more likely cause data communication problems rather than a recurring line fault indication. A shield or cable fault can cause noise or intermittent disruptions, but it doesn’t typically produce the repeated fault condition seen with signaling and line seizure issues. Improper termination can create impedance-related problems and dialing issues, but again, it doesn’t specifically explain repeated fault notifications tied to line activation.