Mesa, AZ Building Safety: Carbon Monoxide Detectors (2026)

6 of the Mesa Residential Code (Title 4, Chapter 3) sets the power requirement for carbon monoxide alarms: 'Carbon monoxide alarms shall receive their primary power from the building wiring where such wiring is served from a commercial power source and, where primary power is interrupted, shall receive power from a battery. ' That means CO alarms installed under new construction or covered alterations must be hardwired into the branch circuit, with battery power reserved for outages rather than serving as the primary source. 6: CO alarms may run on battery power alone in a building without commercial power, and alarms added during an alteration or repair may stay battery-powered if the work doesn't remove interior wall or ceiling finishes and there's no accessible attic, crawl space, or basement to route wiring through.

The section is part of the city's local amendments to the adopted residential code, layered onto the base International Residential Code provisions Mesa enforces for one- and two-family dwelling construction, and is checked at the same inspections that verify smoke alarm wiring.