Codes, Standards, and Regulatory Requirements
The four layers of authority
A fire alarm installer answers to four overlapping layers: (1) NFPA 72, the National Fire Alarm and Signaling Code, which governs design, installation, inspection, testing, and maintenance; (2) NFPA 70 (NEC) Article 760, which governs circuit wiring methods, conductor types, and the power source; (3) occupancy codes - NFPA 101 and the International Building Code - which decide whether detection, notification, and voice evacuation are required and where; and (4) state and local fire codes plus amendments, enforced by the authority having jurisdiction (AHJ).
The edition in force is the one your jurisdiction has adopted, not necessarily the newest published edition. NFPA 72 is generally not retroactive: an existing, legally installed system must be maintained as approved unless a renovation, change of occupancy, or local ordinance triggers an upgrade.
Listing is part of the requirement
Products must be listed for the purpose - control units to UL 864, smoke detectors to UL 268, heat detectors to UL 521, visible appliances to UL 1971, audible appliances to UL 464, and power supplies to UL 1481. Installation must satisfy the code, the listing, and the manufacturer's published instructions simultaneously.
Traps: questions that hinge on the newest edition instead of the adopted one; treating NFPA 72 as a retrofit mandate; and ignoring that a listed device used outside its listing (e.g., a detector installed beyond its listed spacing or temperature range) is a violation even if the drawing shows it.
Rule of thumb: when documents conflict, the most restrictive applicable requirement wins, and the AHJ interprets it.