A to Z how to wire and install a first alert BRK smoke detector from a outlet using MC cable

[@Calico5string1962]

Smoke detectors should be located on a ceiling, preferably at the highest point in a room, as that's where the smoke, combustion products, and heat, go first. A foot or two down on a wall is NOT effective placement, particularly if this is a supposedly "commercial" installation. In some municipalities, the AHJ will fail such an installation. And why don't you use EMT conduit, for these surface-mounted installs? That MC looks so amateurish...