What is one of the first actions to take when a testing failure occurs in a fire detection system?

When a testing failure occurs in a fire detection system, replacing the defective detector is a critical action because it directly addresses the potential source of the failure. Fire detection systems are designed to promptly identify smoke, heat, or flame, and a malfunctioning detector not only undermines the effectiveness of the system but may also pose a safety risk. By replacing the defective detector, you ensure that the system can correctly perform its function of detecting fires and alerting personnel to potential hazards.

While other actions like conducting an electrical survey, reviewing service records, and documenting the incident are important steps in maintenance and troubleshooting, their purpose is typically to identify the broader issues or to understand the context of the failure, rather than immediately resolving the malfunction. Replacing the defective detector is a proactive step to restore the system's reliability and ensure safety is maintained.