The NFPA (National Fire Protection Association) recommends smoke detectors be installed in every bedroom, outside every bedroom, hallway, stairs, and on every level of the house. They should be hardwired and interconnected with a battery backup for emergencies. The on-time wireless smoke detectors are allowed in older homes built without a wired system. The NFPA recommends smoke detectors be replaced every ten years to ensure the reliability of all of the components.
McCurely Electric recommends updating old smoke detectors with 120v hardwired ones. These devices can save the lives of your entire family in a matter of seconds because it provides early warning to help prevent fire fatalities.
Carbon monoxide (CO) detectors should be installed in a central location outside each sleeping area, on every level of the home, and in other locations required by applicable laws, codes, or standards. For the best protection, interconnect all CO alarms throughout the house.