There is an important distinction: the First Alert CO606 is a plug-in carbon monoxide (CO) alarm, not a smoke alarm. Its manual says it is not designed to detect smoke or fire. If you want smoke and CO protection with a plug-in component, pair a smoke alarm with a separate plug-in CO alarm; First Alert sells the SM210/CO606 package as one example. A single combination alarm is another route, but the cited First Alert combination model is battery-powered, not plug-in.
Which option covers the hazards you need?
The phrase “plug-in smoke and carbon monoxide detector” can describe either one device or a set of separate alarms. The researched products support the separate-device approach; they do not establish that a plug-in combination model is unavailable across the entire market.
| What you need | Researched option | What it detects and how it is powered |
|---|---|---|
| Plug-in CO detection | First Alert CO606 | Plug-in CO alarm with battery backup. Its manual says it does not detect smoke or fire. The manual is dated 2014, so check the current product documentation and availability before buying. Manufacturer product page; 2014 user manual. |
| Both hazards, with a plug-in component | First Alert SM210/CO606 package | Two devices: a battery-powered smoke alarm and a separate plug-in CO alarm with battery backup. It is not one plug-in combination alarm. Manufacturer package page. |
| One device for smoke and CO | A properly listed combination alarm | Check the exact model’s documentation for both functions and relevant standards. The cited PC1200 manual describes separate smoke and CO sensors and conformity to UL 217 and UL 2034; it is a battery alarm. The 2014 manual does not establish current availability. PC1200 manual. |
How to choose an alarm for a home or construction project
Compare the exact model documentation rather than relying on a product title or a retailer’s shorthand. A unit advertised as a CO detector may not provide smoke protection, and a smoke alarm does not necessarily detect CO.
- Hazards detected: Confirm whether the alarm detects smoke, CO, or both. The CO606 manual identifies it as a plug-in CO alarm and states: “It is NOT designed to detect smoke, fire, or any other gas.”
- Listing and standards: For a claimed smoke/CO combination alarm, verify that its documentation supports both functions and check for the relevant UL 217 and UL 2034 conformity. UL Solutions discusses CO alarm code considerations here.
- Power and backup: Determine whether the alarm is plug-in with battery backup, battery-only, or hardwired. Check what happens during a power interruption and follow the model’s instructions for backup batteries.
- Placement and local requirements: Confirm the permitted locations and installation method in the alarm’s manual and the requirements for the specific jurisdiction.
- Signals, testing and service life: Review the instructions for testing, alarm patterns, maintenance, battery replacement and end-of-life warnings before installation.
- Current model details: Product names and availability can change. Check the manufacturer’s current listing and documentation rather than assuming an older manual describes a current model or package.
Where to install smoke and CO alarms
The U.S. Consumer Product Safety Commission (CPSC) recommends smoke alarms on every level of a home, outside sleeping areas and inside each bedroom. For CO, it recommends alarms on every level and outside sleeping areas. Local requirements may add detail; consult the applicable code and the alarm’s model-specific instructions. CPSC CO alarm guidance.
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#1 Best Overall
- Keep your family safe with this easy to use plug in carbon monoxide alarm; It works with any standard outlet and also has a battery backup for continuous monitoring of Carbon Monoxide levels, even if there's a power failure
- Features an advanced electrochemical carbon monoxide sensor that accurately detects carbon monoxide levels, no matter where the detector is placed in the room
- Simple to use, with a single test/silence button; a loud 85 decibel alarm sounds when Carbon Monoxide levels reach dangerous levels. Low battery signal mute, quiets low battery signal for upto 8 hours
- To ensure complete protection make sure to place one on each level of your home and in each bedroom
- 7 year limited warranty; Equipped with end of life signal chirp, so you know when it’s time to replace the unit for safety
Do not treat “plug-in” as permission to use any convenient outlet. Follow the alarm manual’s location guidance, make sure the alarm can be heard, and avoid obstructing airflow. Smoke and combination alarms have smoke-specific placement instructions; CO-only placement guidance is not a substitute. First Alert’s placement guide describes smoke alarm positioning on walls and ceilings and advises following local codes and the individual alarm manual.
CO alarm figures in the CO606 manual: what they mean
The 2014 CO606 manual reproduces UL 2034 alarm points for specified CO concentrations and time ranges. These are alarm thresholds described in that manual, not recommended safe exposure limits:
Rank #2
- Easy Installation - simply plug-in to a standard, 120V outlet in your home
- 2-AA battery backup provides protection during a power outage
- 85-decibel alarm announces when carbon monoxide is detected
- Peak Level Memory records the last time carbon monoxide was detected or when the unit was last tested
- Test-Hush Button makes testing the detector or silencing false alarms easy
| CO concentration | Alarm time range stated in the 2014 CO606 manual |
|---|---|
| 70 ppm | 60 to 240 minutes |
| 150 ppm | 10 to 50 minutes |
| 400 ppm | 4 to 15 minutes |
Do not wait for an alarm to sound if you suspect CO. Leave the area and follow local emergency guidance. First Alert provides additional CO safety information.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.A model-specific plug-in detector warning
In September 2026, the CPSC warned consumers to stop using the KH158 4-in-1 plug-in natural gas/CO detector because it may fail to alert users to hazardous CO. The warning names that model; it is not evidence that all plug-in CO alarms are unsafe. The CPSC advises consumers to choose CO alarms that meet UL 2034. Read the CPSC warning.
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Best Value
- Easy Installation - simply plug-in to a standard, 120V outlet in your home
- 9-volt battery backup provides protection during a power outage
- Digital LED display shows the level of carbon monoxide the CO alarm is sensing
- 85-decibel alarm announces when carbon monoxide is detected
- Peak Level Memory records the last time carbon monoxide was detected or when the unit was last tested
Rank #4
- DETECTS CARBON MONOXIDE: Model COP monitors CO levels & sounds a loud 85 dB alarm to signal evacuation; sleep peacefully with no nighttime chirps; LED warning light indicates hazard; Test/Hush button for quick checks
- PLUG-IN POWER WITH BATTERY BACKUP: CO detector plug-in operates on 120V AC with 2 AA backup batteries (included) for detection during outages; rotating plug fits vertical or horizontal outlets; includes power surge immunity to help maintain performance
- TRAVEL-READY DESIGN*: Compact carbon monoxide detector is suitable for use at home or for travel; lightweight design allows you to take it on the go to use in hotels or vacation rentals when detection is needed away from home
- TESTED & TRUSTED: This carbon monoxide alarm is rigorously tested to meet UL 2034 5th Edition standards, and is ETL Listed; includes a 10-year limited warranty on alarm
- BUILT FOR EVERY HOUSEHOLD: Designed to help provide dependable carbon monoxide monitoring for everyday residential use; supports renters, homeowners, and pet owners seeking added awareness and protection from CO hazards in the home
Rank #3
- Easy Installation - simply plug-in to a standard, 120V outlet in your home
- 9-volt battery backup provides protection during a power outage
- Digital LED display shows the level of carbon monoxide the CO alarm is sensing or states "GAS" when explosive gas is present
- 85-decibel alarm announces when carbon monoxide or explosive gas is detected
- Peak Level Memory records the last time carbon monoxide was detected or when the unit was last tested
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