Testing, Inspection, and Maintenance
Three different verbs
Inspect means look (visual condition, labeling, obstruction). Test means operate the device and confirm the response at the panel and at the appliances. Maintain means correct what you found. Exams exploit the overlap: "the technician visually confirmed the detector was undamaged" is an inspection, not a test.
Acceptance testing is not sampling
At acceptance, test 100% of initiating devices and verify every alarm, supervisory, and trouble function, including primary and secondary power, remote annunciation, and audibility. Sampling a percentage of devices is not permitted at acceptance. Smoke detector sensitivity must be checked within one year after installation and every alternate year thereafter unless a different schedule is approved. Periodic inspection and testing frequencies come from a table in NFPA 72 - commonly cited values include annual for smoke and heat detectors, semiannual for manual fire alarm boxes and notification appliances, and quarterly-or-semiannual for waterflow and valve-supervisory devices depending on edition. Confirm against the adopted edition rather than memory.
Test methods and records
Smoke detectors are tested with listed aerosol or a manufacturer-approved method, heat detectors with a listed heat source, and pull stations by operating the mechanism. Record results on the record of inspection and testing, retain them, and note deficiencies, impairments, and the date the system was returned to service. Never leave a system impaired without notifying the owner and, where required, the supervising station.
Diagnostic rule of thumb
Trouble on an entire circuit: suspect the panel, the circuit card, or primary power first. Trouble on part of a circuit: suspect a field device, a loose terminal, or a cut conductor - and if a device in the middle of a Class B circuit can still be operated and report, the break is downstream of it.