California’s Carbon Monoxide Poisoning Prevention Act of 2010 requires that all residential property be equipped with a carbon monoxide alarm when the property has a “fossil fuel” burning heater or appliance, fireplace, or an attached garage. The law requires that: All single-family detached homes (owner or tenant occupied) must be equipped with an alarm on or before July 1, 2011. All other residential units must be equipped with an alarm on or before January 1, 2013. Outlined below and with specific exceptions, a carbon monoxide alarm may be battery powered, a plug-in device with battery backup, or hard-wired into the dwelling unit with a battery backup.