Smoke detectors in one- and two-family dwellings must be replaced every

• A. Every 10 years
• B. Every 5 years
• C. Every 15 years
• D. Every 20 years

Answer: (A)

Ten years is the practical service life for residential smoke alarms. Over time the sensor components, electronics, and housing can degrade from exposure to dust, humidity, and temperature changes, which lowers the detector’s reliability and sensitivity. A lot of models use a sealed 10-year battery, so the entire unit is replaced at the end of that period. Even when batteries are replaceable, aging can weaken performance, so reaching about ten years is the established point to ensure the alarm will still respond reliably in a real fire. Replacing sooner isn’t necessary for most units, but waiting longer than ten years increases the risk of failing to detect smoke or delaying an alarm. That’s why the ten-year replacement interval is the correct guideline.