What is the life span of residential smoke detectors, after which they should be replaced?

• A. Ten years
• B. Five years
• C. Fifteen years
• D. Twenty years

Answer: (A)

Residential smoke detectors have a limited service life because the sensors age and their ability to detect smoke can drift over time. After about ten years, the chance that the alarm will reliably detect smoke increases, so replacing the unit helps ensure it will work when needed. Many standards and manufacturers set ten years as the typical replacement interval, and devices with sealed 10-year batteries are designed to be retired after a decade, with the entire unit replaced. Even if a unit still seems to operate, its sensing components and electronics may no longer be dependable after ten years.

Five years is sooner than necessary for most homes, while fifteen or twenty years surpasses the recommended lifespan and increases the risk of undetected fires due to degraded sensitivity. Replacing at ten years keeps your protection consistent and reduces the chance of a failed alarm.