AlarmSwap

Guide

How to find your smoke alarm's date and when it expires, by brand

Quick answer

NFPA says every smoke alarm has to be replaced 10 years after the date it was made.1

USFA's 'Check the Date' handout says to take the alarm down and read the manufacture date on its back, then put it back up only if it is under 10 years old.2

NFPA says chirping that carries on after a fresh battery means the alarm has reached the end of its life and the whole unit needs replacing.1

Last checked

Check the date

  1. Turn off power before you take a hardwired alarm down. Kidde says to switch off the circuit breaker (or pull the fuse) before removing an installed alarm from its bracket, and to restore power only after every alarm is back up.3
  2. Read the manufacture date on the alarm. USFA's 'Check the Date' handout says to take the alarm down and read the manufacture date on its back, then put it back up only if it is under 10 years old.2
  3. Count the years from that date. NFPA says every smoke alarm has to be replaced 10 years after the date it was made.1
  4. If the date is missing, replace the alarm. X-Sense says to throw out and replace an alarm that shows no manufacturing date.9
  5. On an interconnected loop, stay with models the maker lists. Kidde warns that putting unlisted brands or models on its interconnect wire could cause nuisance alarms, failure to alarm, or damage.3

Before you take a wired alarm down

Hardwired alarms run on household power, so the order matters.

  • Kidde says to switch off the circuit breaker (or pull the fuse) before removing an installed alarm from its bracket, and to restore power only after every alarm is back up.3
  • NFPA advises that only qualified electricians install hardwired smoke alarms.1

By brand

Find the logo on the front of the alarm, then look at its row.

Kidde

Where the date is
Stamped on the label on the back of the alarm.4
How long it lasts
Smoke and heat alarms: replace every 10 years. CO and combination smoke/CO alarms: every 7–10 years, depending on the model.5

Model pages: i12060, i12040

First Alert

Where the date is
The manufacture date is on the back of the smoke or CO alarm.6
How long it lasts
Replace once it is 10 years old or older, and right away if it fails its test.6

Google Nest Protect

How long it lasts
2nd-generation Nest Protect: 10 years from the date it was made. 1st generation: 7 years.7
Where the date is
In the Nest or Google Home app: open the Protect's settings and look for the 'Replace by' date under its technical information.7
When it has expired
It double-chirps once a minute until it is replaced.8

X-Sense

How long it lasts
X-Sense's FAQ gives smoke alarms a life of 8 to 10 years, then says to replace the whole unit.9
No date on it?
X-Sense says to throw out and replace an alarm that shows no manufacturing date.9

Universal Security Instruments (USI)

How long it lasts
USI recommends replacing smoke, CO and natural-gas alarms at least every 10 years, or sooner if they act up.10
Sealed batteries
Many USI alarms have a sealed 10-year battery that is never replaced during the alarm's life; batteries in other models should be changed at least yearly.10

Firex

What Kidde says
Kidde, which bought the maker of Firex alarms in 2009, says Firex owners should replace them with a current Kidde model.3

Model pages: i4618

Can't read the date?

Labels fade, get painted over, or were never printed. A fresh battery does not change how old the alarm is.

  • X-Sense: an alarm with no manufacturing date should be discarded and replaced.9
  • NFPA: test every alarm monthly with its button; if it stays silent, change the battery, or replace the whole unit if it is over 10 years old.1

Replacing one alarm in a linked set

If your alarms all go off together, they share an interconnect wire, and not every new alarm can join an old loop.

  • Kidde warns that putting unlisted brands or models on its interconnect wire could cause nuisance alarms, failure to alarm, or damage.3
  • Before reusing or giving away an old alarm, search CPSC's recall list for its model.11

Common questions

When does NFPA say a smoke alarm has to be replaced?

NFPA says every smoke alarm has to be replaced 10 years after the date it was made.1

Where do you look for a smoke alarm's manufacture date?

USFA's 'Check the Date' handout says to take the alarm down and read the manufacture date on its back, then put it back up only if it is under 10 years old.2

What does chirping that continues after a new battery mean?

NFPA says chirping that carries on after a fresh battery means the alarm has reached the end of its life and the whole unit needs replacing.1

What should you do if a smoke alarm shows no manufacture date?

X-Sense says to throw out and replace an alarm that shows no manufacturing date.9

Can you add any brand to a Kidde interconnect loop?

Kidde warns that putting unlisted brands or models on its interconnect wire could cause nuisance alarms, failure to alarm, or damage.3

Can't read the date?

X-Sense: an alarm with no manufacturing date should be discarded and replaced.9 NFPA: test every alarm monthly with its button; if it stays silent, change the battery, or replace the whole unit if it is over 10 years old.1

Sources

  1. NFPA — Smoke Alarm Information checked 2026-10-31
  2. USFA — Don't Wait, Check the Date! (PDF handout) checked 2026-10-31
  3. Kidde — What Other Products Will Kidde Alarms Interconnect With? checked 2026-10-31
  4. Kidde — How to Find the Date of Manufacture on an Alarm checked 2026-10-31
  5. Kidde — Alarm Replacement Guide checked 2026-10-31
  6. First Alert — 10-Year Battery Alarms (How to check your alarms) checked 2026-10-31
  7. Google Nest Help — When to replace your Nest Protect checked 2026-10-31
  8. Google Nest Help — Nest Protect lights and sounds checked 2026-10-31
  9. X-Sense — Smoke Detector Fire Alarms FAQ checked 2026-10-31
  10. Universal Security Instruments — Smoke & Fire Safety FAQs checked 2026-10-31
  11. CPSC — Recalls & Product Safety Warnings checked 2026-10-31

Facts are restated in our own words. If a source page changes, the "checked" date tells you how fresh our reading is. Spot something out of date? Open an issue on GitHub.

Published October 31, 2026.