Kidde · Hardwired smoke + CO alarm
Kidde KN-COSM-IBA: age, expiry and what replaces it
Quick answer
A wired-in Kidde alarm that senses both smoke (ionization) and carbon monoxide, speaks its warnings, and runs on two AA batteries when the power is out. Ten years after first power-up it double-beeps every 30 seconds, and the guide warns it no longer senses CO in that state. Kidde's page names the 30CUAR as its upgrade.
Last checked
At a glance
- Sensors
- Ionization for smoke, electrochemical for carbon monoxide1
- Power
- 120 V AC house wiring with two AA backup batteries, loaded through a front door without taking the alarm off its bracket1
- Backup batteries
- The guide names the AA cells it approves (for example Duracell MN1500 or Energizer E91) and warns against using others2
- Where the date is
- The date of manufacture and the model number are on the back of the alarm. The guide also asks you to write a "replace by" date, 10 years from first power-up, on the alarm2
- When to replace
- Ten years after first power-up it beeps twice every 30 seconds. The guide says to replace it at once, because it will not detect CO in that state2
- Snoozing the end-of-life signal
- The button silences the end-of-life chirp for about 3 days at a time, for no more than 30 days in total2
- Low-battery signal
- Once a minute: one chirp, a red LED flash and the spoken words "low battery", for at least seven days. A low-battery hush quiets it for about 10 hours while you get batteries2
- Voice warnings
- It announces "Fire!" or a carbon monoxide warning so you can tell the two alarms apart1
- Peak level memory
- It remembers if it has seen CO at 100 ppm or more since it was last reset1
- Interconnect
- Up to 24 Kidde devices on one loop, 18 of which can set off the rest1
- Other brands on the loop
- The guide approves it only with Kidde/Nighthawk products and says it is not approved with any other brand2
- Warranty
- 10-year limited1
Replacing it
- Replacement named by Kidde
- Kidde's KN-COSM-IBA page shows the 30CUAR, a hardwired smoke + CO alarm with AA battery backup, under "Upgrade to"1
- Keep the old wiring plug
- Kidde's 20-9003 adapter guide lists the KN-COSM-IBA among the older harnesses it can join to a new Kidde alarm with the newer connector3
- Check the pairing first
- Only connect alarms that Kidde lists as compatible; Kidde says unlisted equipment on the interconnect wire can cause nuisance alarms, a failure to alarm, or damage4
- Smoke + CO alarms in general
- Kidde's replacement guide gives CO and combination alarms 7–10 years depending on the model; this one's guide gives 105
- Recalls
- Search CPSC's recall list for your exact model before reusing or reselling an alarm6
Related models
Other models that cite the same adapter
Each link goes to another model page that cites the same adapter document. Whether two alarms can share a plug is answered in that document, on the model page.
- Firex i4618 20-9003
- First Alert ADK-12 20-9003
- Kidde i12010S 20-9003
- Kidde i12040 20-9003
- Kidde i12060 20-9003
Common questions
Where is the date on a Kidde KN-COSM-IBA?
The date of manufacture and the model number are on the back of the alarm. The guide also asks you to write a "replace by" date, 10 years from first power-up, on the alarm2
When should a Kidde KN-COSM-IBA be replaced?
Ten years after first power-up it beeps twice every 30 seconds. The guide says to replace it at once, because it will not detect CO in that state2
What replaces the Kidde KN-COSM-IBA?
Kidde's KN-COSM-IBA page shows the 30CUAR, a hardwired smoke + CO alarm with AA battery backup, under "Upgrade to"1
Which adapter guide lists the Kidde KN-COSM-IBA?
Kidde's 20-9003 adapter guide lists the KN-COSM-IBA among the older harnesses it can join to a new Kidde alarm with the newer connector3
Sources
- Kidde — Hardwired Combination CO & Smoke Alarm KN-COSM-IBA (product page) checked 2026-11-04
- Kidde — KN-COSM-IBA Smoke & CO Alarm User Guide (PDF) checked 2026-11-04
- Kidde — 20-9003 Wiring Adapter User Guide (PDF) checked 2026-11-04
- Kidde — What Other Products Will Kidde Alarms Interconnect With? checked 2026-11-04
- Kidde — Alarm Replacement Guide checked 2026-11-04
- CPSC — Recalls & Product Safety Warnings checked 2026-11-04
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 November 4, 2026. Part of the Kidde brand hub.