Inspection, Testing, and Maintenance
Frequency table thinking
NFPA 72 Chapter 14 sets minimum inspection, testing, and maintenance intervals. Anchors worth memorizing: initiating devices (smoke, heat, duct, manual stations) - annually; notification appliances - semiannually; waterflow switches and valve tamper switches - quarterly; batteries - inspected semiannually with periodic load testing; smoke detector sensitivity - within one year of installation and every two years thereafter, or per the manufacturer's published instructions. In general, every device must be tested at its own interval; sampling shortcuts are not available except where the code explicitly provides them.
Process, not just frequency
Testing is a documented, coordinated activity: notify the monitoring company and the AHJ before disabling anything, use the fire watch while a system is impaired, restore and verify afterward, and record results on the appropriate forms. Records must be retained and made available to the AHJ. A system that has never been acceptance-tested is not "grandfathered" out of testing.
Worked example (planning rule of thumb): a 300-device addressable system tested annually, allowing roughly one minute per device for actuation plus documentation, needs about 5 hours of field time plus travel - not a one-hour walkthrough. Bid the labor to the test, not to the panel count.
Traps: confusing annual and semiannual requirements; testing a detector with a magnet and calling it a smoke test; forgetting the remote test method for duct detectors; failing to re-verify signal receipt at the supervising station after the test; and leaving a system in test mode or disabled at the end of the shift.