Tempe, AZ Fire Regulations: Smoke Detectors (2026)

6 controls how smoke alarms must be wired inside dwellings built or altered under the current code cycle, most recently amended by Ordinance No. 24, effective June 4, 2026. The rule requires that a smoke alarm draw its primary power from the building's electrical wiring wherever that wiring is fed from a commercial power source, and switch to a battery only when the primary circuit is interrupted. The wiring feeding the alarm must be permanent, with no disconnect switch other than the breaker or fuse protecting the circuit from overcurrent, so a homeowner cannot simply flip off power to a hardwired alarm.

Two exceptions apply. A smoke alarm can run on battery power alone if the building has no commercial electric service at all, which covers off-grid accessory structures. 2 can also keep an existing battery-only alarm if the work does not remove interior wall or ceiling finishes, unless an attic, crawl space or basement is open and available to run new wiring, in which case hardwiring is still required. The Tempe Building Safety Division checks compliance at the permit and final-inspection stage for new single-family homes, additions, and any remodel that opens up wall or ceiling cavities in bedrooms and hallways.

Because this provision sits in the residential building code rather than the fire code, it is a construction-permit requirement rather than a fire-inspection sweep of existing occupied homes, so most enforcement happens when a permit is pulled, not through door-to-door checks of already-occupied houses.