Smoke detector chirping every minute — Zaandam, North Holland

A smoke detector that chirps once every 30–60 seconds is signaling a low battery, end-of-life status, or sensor contamination. Replace the battery first — even hardwired detectors have a backup 9V or lithium cell that needs replacement every 6–12 months. If chirping continues with a fresh battery, check the manufacture date printed on the back: smoke detectors expire after 10 years (the radioactive sensor element degrades), and they will chirp continuously when expired. Dust and cobwebs inside the detector also trigger false low-battery chirps — vacuum the unit gently with a brush attachment. If you have multiple hardwired interconnected detectors that all chirp together, the issue is usually one bad unit on the circuit. An electrician charges $75–$200 to replace a hardwired smoke detector, or $300–$600 to replace a full set of 4–6 interconnected units. Never disable a chirping detector by removing the battery — it's a serious fire safety risk.