Kidde Hardwired Smoke and Carbon Monoxide Detector
- Combination ionization smoke and carbon monoxide alarm
- 120 volt AC wired, with **2 AA** battery backup
- Interconnects up to 24 Kidde devices
- Voice alert, Hush silences about 9 minutes
- 10 year limited warranty
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A hardwired Kidde smoke and carbon monoxide combination alarm with voice alerts and battery backup. Listed as a previous model, and it needs wiring.
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ASIN: B086S4Y9H5Category: Carbon Monoxide Detectors
Overview
Not a battery-only alarm, this Kidde unit is an AC wired combination detector that combines an ionization smoke sensor with a carbon monoxide sensor. A voice warning announces fire, carbon monoxide or a low battery.
A single hardwired unit saves a ceiling spot and links with others for whole-home alerts. Battery backup carries protection through outages. Hardwiring requires a household circuit, and the product style is listed as a previous model.
Who it's for
Homeowners with an existing hardwired alarm circuit get a combination replacement that interconnects with other Kidde devices. Anyone without wiring in place should consider a plug-in or battery model.
Pros and cons
- Smoke and carbon monoxide in one unit
- Voice alerts name the hazard
- Battery backup during outages
- Interconnects with other Kidde alarms
- Needs hardwired installation
- Ionization smoke sensing only
- Listed as a previous model
- Battery inclusion not stated
Performance notes
An ionization chamber senses fire particles and an electrochemical cell senses carbon monoxide. Alarms sound when either threshold is met and linked units sound together. The Hush feature silences nuisance alarms for a limited time.
Where it stands among carbon monoxide detectors
- #4 most-searched brand and model of the 17 carbon monoxide detectors lines we track (by search demand, not sales).
From the specs of the 30 carbon monoxide detectors we list; not a test result.
Specifications
| Brand | Kidde |
|---|---|
| Dimensions & fit | |
| Item Dimensions D X W X H | 1.8 x 5.6 x 5.6 inches |
| Item weight | 16 ounces |
| Capacity & performance | |
| Upper Temperature Rating | 37.8 °C |
| Power & efficiency | |
| Power Source | Corded Electric (120VAC) with 2 AA battery backup |
| Construction & materials | |
| Color | White |
| Compatibility & installation | |
| Compatible Devices | Up to 24 Kidde devices |
| Included components | |
| Unit Count | 1 Count |
| Warranty & support | |
| Manufacturer Warranty Description | 10 Year Limited |
| Other details | |
| Sensor Type | Ionization |
| Alarm | Audible |
| Product Style | Previous Model |
| Item Type Name | Combination Smoke & Carbon Monoxide Detector |
| BuiltIn Media | Alarm |
| Mfr Part Number | 21026041 |
| Operating Humidity | 10% to 95% relative humidity, non-condensing |
Frequently asked questions
How many Kidde alarms can interconnect with the KN-COSM-IBA?
Up to 24 Kidde devices, though the listing notes a limit of 18 initiating devices under NFPA rules.
How long does the Kidde KN-COSM-IBA last?
The listing recommends replacing carbon monoxide alarms every 5 to 7 years and gives a 10 year limited warranty.