Smoke detectors must be installed within ____ feet of a door to a sleeping room.

Smoke detectors are critical for early fire detection, especially in residential settings. The standard recommendation is that smoke detectors should be installed within a certain distance from any sleeping areas to ensure they can effectively alert occupants if there is a fire, particularly while they are asleep. The requirement that smoke detectors be installed within 21 feet of a door to a sleeping room ensures that the devices are close enough to be effective in providing an audible alarm that can wake sleeping individuals. This distance is based on research regarding how sound travels and how quickly people can respond in emergencies. When smoke detectors are positioned within this range, it minimizes the risk of smoke or fire going undetected during the night, thereby enhancing safety.