Kidde Hardwired Smoke and Carbon Monoxide Detector
- Power Source: Corded Electric
- Sensor Type: Ionization
- Alarm: Audible
- Operating Humidity: 10 to 95% Relative Humidity, Non-Condensing
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A solid pick for extending an existing hardwired Kidde interconnect system, less useful as a first, standalone alarm in an unwired home.
As an Amazon Associate I earn from qualifying purchases. ProductDome earns a commission when you buy through links on this page.
ASIN: B086S4Y9H5Category: Carbon Monoxide Detectors
Overview
Hardwired combination smoke and carbon monoxide alarm from Kidde with ionization sensing, spoken voice alerts, and 2-AA battery backup for power outages. Built for whole-house interconnected systems rather than a single stand-alone unit.
The category listing files this under carbon monoxide detectors alone, but the title and specs describe a combined smoke and CO alarm on ionization sensing. It runs on 120VAC household wiring with battery backup, and its interconnect is specific to other KN-COSM-IBA models rather than any Kidde alarm.
- Ionization sensor for fast-flaming fire detection
- Voice alerts spoken for fire, CO, or low battery
- 2-AA battery backup during power outages
- Interconnects up to 24 Kidde devices, 18 initiating
Who it's for
Homeowners or electricians expanding or replacing a hardwired, interconnected Kidde KN-COSM-IBA alarm system. Not a fit for anyone who wants a battery-only unit with no wiring.
Pros and cons
- Combines smoke and CO detection in one hardwired unit
- Spoken voice alerts identify fire, CO or low battery by name
- 2-AA battery backup keeps it running through outages
- Interconnects with up to 24 Kidde devices, 18 of them able to initiate
- Requires 120VAC wiring, not a drop-in for unwired homes
- Interconnect is limited to matching KN-COSM-IBA models
- No digital CO ppm readout, LED and voice only
Performance notes
Ionization sensing picks up fast-flaming fires, and the unit announces which hazard triggered it by voice: fire, carbon monoxide, or low battery, rather than a single generic tone. The test-hush button silences a false alarm for about 9 minutes, and tamper-resistant mounting discourages someone from pulling the unit off the wall.
Specifications
| Brand | Kidde |
|---|---|
| Dimensions & fit | |
| Item Weight | 1 pound |
| Item Dimensions D X W X H | 1.8 × 5.6 × 5.6 inches |
| Capacity & performance | |
| Upper Temperature Rating | 100 °F |
| Power & efficiency | |
| Power Source | Corded Electric |
| Construction & materials | |
| Color | White |
| Compatibility & installation | |
| Compatible Devices | Up To 24 Kidde Devices |
| Included components | |
| Unit Count | 1 |
| Warranty & support | |
| Manufacturer Warranty Description | 10 Year Limited |
| Other details | |
| Sensor Type | Ionization |
| Alarm | Audible |
| Operating Humidity | 10 to 95% Relative Humidity, Non-Condensing |
| Number Of Items | 1 |
| Product Style | Previous Model |
| Mfr Part Number | 21026041 |
| Builtin Media | Alarm |
| Item Type Name | Combination Smoke & Carbon Monoxide Detector |
Frequently asked questions
Does the Kidde KN-COSM-IBA need to be hardwired?
Yes, it runs on a 120VAC household power source with 2-AA battery backup for outages, so it is installed as a wired unit rather than a plug-in or battery-only alarm.
Can this Kidde detector interconnect with alarms I already own?
It interconnects with other KN-COSM-IBA models, up to 24 devices total, with as many as 18 able to initiate the alarm.
What does the voice alert actually say?
It announces "Fire! Fire!", "Warning! Carbon Monoxide!" or "Low Battery!" depending on which condition triggers it.