Which type of maintenance should be conducted on smoke detectors at least once every six months?

The appropriate type of maintenance that should be conducted on smoke detectors at least once every six months is cleaning by a COF holder. Regular maintenance, including cleaning, is essential for the proper functioning of smoke detectors, as dust, debris, and other contaminants can accumulate and impair the detector's sensitivity or even prevent it from functioning correctly.

Cleaning ensures that the smoke detector can accurately detect smoke particles, which is critical for the safety of the environment in which they are installed. A Certificate of Fitness (COF) holder must perform this maintenance, as they are trained to properly clean the detectors according to the manufacturer’s guidelines and local regulations.

While visual inspection is important, it generally does not involve the thorough cleaning required to maintain optimal detector performance. Replacement, while necessary at some point, is not a periodic requirement every six months. Configuration testing is also crucial but is conducted less frequently than biannually and focuses on the operational aspects of the system rather than the physical condition of the detectors themselves. Thus, cleaning by a COF holder is the necessary maintenance activity required every six months.