Does Smoke alarms expire?
The sensing element degrades: ionisation chambers accumulate dust and their radioactive source decays slowly, and photoelectric sensors drift as their optical surfaces age. Neither failure announces itself, and the test button checks the sounder and the battery rather than the sensor. The date is printed on the back of the unit, and a house bought second-hand very often has alarms older than the owner realises. Carbon monoxide alarms have shorter lives still, typically seven years, and are a separate device from a smoke alarm even when the two are combined.
How to store it
- Not applicable — but replace all of them at once, since they were almost certainly installed together.
How to tell it has gone
- None. The date on the back is the only guide.
- Chirping usually means a low battery, not end of life; some units chirp differently at end of life.
"Use by" and "best before" are legally different. Use-by is a safety date and should be respected; best-before is about quality, and food is usually fine well past it. Where the two diverge matters, the page above says which applies.
Common questions
- Does Smoke alarms expire?
- Ten years from manufacture, then the whole unit — not just the battery.
- How long does Smoke alarms last?
- 10 years from the manufacture date on the back
Related pages
- Does Sunscreen expire? No. Sunscreen is regulated as a drug and must hold its stated SPF for three years — after that, assume it does not.
- Does Condoms expire? No. Latex degrades, the date is regulated, and there is no visible warning before failure.
- Does Infant formula expire? No — this is the one supermarket product whose date is legally binding and should be obeyed exactly.
- Does Mascara and eye makeup expire? Three months after opening, and this is one of the cosmetic rules worth taking seriously.
- Does Child car seats expire? Yes, genuinely — six to ten years from manufacture, moulded into the shell.
- Does Cycle and motorcycle helmets expire? Five years is the usual manufacturer figure, and any single significant impact ends it immediately.
- Does Contact lens solution expire? No. The date is real, and the opened bottle has a much shorter life than the printed date suggests.
- Does Plasters and sterile dressings expire? The adhesive fails and, more importantly, the sterile seal is only guaranteed to the date.
- Does Honey expire? Does not expire
- Does Eggs expire? Degrades in quality
- Does Medicines expire? Degrades in quality
- Does Milk expire? Has a real expiry date
- Does Salt expire? Does not expire
- Does Frozen food expire? Indefinite if stored properly
Sources
- Official vendor product documentation — At One Place