NFPA 72 Household Smoke, Heat and CO Alarms
Where They Go, How They Are Powered and Interconnected (Chapter 29)
NFPA 72-2019 National Fire Alarm and Signaling Code (DBPR CIB reference list); read in the NFPA free-access viewer 2026-09-21 · Reviewed 2026-09-21
Chapter 29 is the residential electrician's chapter: where smoke and CO alarms go in a dwelling, how they are powered, and how they interconnect. The Residential exam tests it under "Residential Life Safety and ADA". Numbers: 21 ft, 1000 sq ft / 30 ft / 500 sq ft, 85 dBA at 10 ft, 7 days + 4 min, 10 years, 24 h + 4 min, 10 ft / 20 ft / 6 ft, 36 in., 12 in., 4 in., 18 / 12 and 64 / 42, 20 s, 80 min, 100 ft.
1. Required locations — 29.8.1, 29.7.1
- Smoke alarms (or system smoke detectors): in every sleeping room and guest room; outside each separate sleeping area, in the immediate vicinity, within 21 ft of any sleeping-room door measured along the path of travel; on every level including basements, excluding crawl spaces and unfinished attics.
- Where a level exceeds 1000 sq ft, add alarms so every ceiling point is within 30 ft travel distance of one, or one alarm per 500 sq ft.
- In new construction, alarms are interconnected so all sound together.
- CO alarms (29.7.1.1, where required): outside each sleeping area within 21 ft of a sleeping-room door, on every occupiable level including basements (not attics/crawl spaces), in sleeping rooms with fuel-burning appliances, and where other codes require; two or more CO alarms in a unit are interconnected (29.7.2).
- Heat alarms (29.10.4) are the choice for kitchens, garages and attics where smoke alarms would nuisance trip — listed at 50 ft spacing, rated at least 25 °F above the normal ambient and not more than 50 °F above the maximum anticipated ambient.
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