First Alert SMCO100V-AC Plug-In Smoke and Carbon Monoxide Alarm with Voice Alert and Battery Backup
$61.23
$79.99
Final price set by Amazon · may vary
EDITORIAL REVIEW: 4.5/5 WC Safety Review — First Alert SMCO100V-AC Plug-In Smoke and CO Alarm Editorial assessment by the WC Safety Editorial Team, based on published First Alert specifications and category fit. W...
Key Features
- First Alert's Precision Detection advanced sensing technology complies with new industry standards to reduce cooking nuisance alarms and provides early warning in the event of a home fire emergency
- Voice & location alerts tell you what the danger is and its location to help you escape safely
- Through early warning interconnect, when one alarm sounds, all compatible alarms* will sound
- Battery backup provides continuous protection during power outages
- Quick Connect Plug allows for easy installation with no need to rewire
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EDITORIAL REVIEW: 4.5/5 WC Safety Review — First Alert SMCO100V-AC Plug-In Smoke and CO Alarm
Editorial assessment by the WC Safety Editorial Team, based on published First Alert specifications and category fit. We did not laboratory-test this product.
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First Alert SMCO100V-AC Plug-In Smoke and Carbon Monoxide Alarm with Voice Alert and Battery Backup Overview
The First Alert SMCO100V-AC is a plug-in combination alarm that monitors for both smoke and carbon monoxide (CO) in one device, so a single unit guards against fire and the colorless, odorless gas you can't detect on your own. When it senses a threat, the built-in voice alert announces whether the danger is smoke or carbon monoxide, helping you respond faster than a generic beep.
It plugs into a standard wall outlet for continuous AC power and carries battery backup, so it keeps watching during a blackout. Because it combines two detectors, it's a space-saving choice for bedrooms, hallways outside sleeping areas, and finished basements. Smoke alarms are built to the UL 217 standard and CO alarms to UL 2034; a combination unit like this addresses both. For whole-home coverage, pair it with additional units on every level and browse our combination smoke/CO alarms, dedicated smoke detectors, and carbon monoxide alarms. New buyers can compare top picks in our best CO detectors and best smoke detectors guides.
What It Is Built For
| Use case | Fit | Buyer guidance |
|---|---|---|
| Bedrooms and hallways near sleeping areas | Excellent | Combination smoke + CO with voice alert wakes sleepers and names the hazard; install inside or just outside each bedroom near an outlet. |
| Living rooms, dens, and finished basements with an outlet | Excellent | Plug-in power with battery backup gives continuous coverage; place on every level of the home per the CO detector placement guide. |
| Replacing an aging single-function alarm | Strong | One unit covers both fire and CO, freeing an outlet and simplifying maintenance versus running separate smoke and CO devices. |
| Whole-home interconnected fire system | Limited | This is a standalone plug-in alarm, not a hardwired interconnect unit; if you need linked alarms, choose a hardwired interconnectable model instead. |
| Garage, attic, or unconditioned spaces | Poor | Temperature and humidity extremes are outside the rated range for residential alarms; use only in living spaces. |
A smoke alarm and a carbon-monoxide alarm detect different hazards — install both (or a combination unit) on every level and near each sleeping area, and interconnect them where possible. Test monthly and replace at the unit's end-of-life date (CO sensors typically last 5–10 years; smoke alarms about 10). Carbon monoxide is colorless and odorless, so a working alarm is your only warning — look for UL 2034 (CO) / UL 217 (smoke) listing. See how to test a smoke & CO alarm and the CO detector placement guide.
Pros & Cons
Pros
- One unit detects both smoke and carbon monoxide, covering two hazards at once
- Voice alert announces whether the threat is smoke or CO instead of an ambiguous beep
- Plug-in AC power with battery backup keeps it running during outages
- Simple outlet install with no hardwiring or electrician required
- Carbon monoxide is colorless and odorless, so a dedicated CO sensor adds protection a smoke alarm alone can't
Cons
- Standalone plug-in design is not hardwired or interconnectable with other alarms
- Occupies a wall outlet, which may be a constraint in tight rooms
- Combination sensors reach end of life and the whole unit must be replaced (CO sensors typically last about 5-10 years, smoke up to 10)
- Requires periodic battery-backup changes and monthly testing
How It Compares
Within First Alert's combination and CO lineup, the SMCO100V-AC is the plug-in, voice-alert pick. Step up to the First Alert CO511 wireless interconnect carbon monoxide alarm with voice alert if you want linked alarms that sound together, though that unit is CO-only. For a battery-powered CO alarm with a digital readout, the First Alert CO250 battery carbon monoxide alarm is a tamper-resistant single-function option. If you only need fire detection, see our smoke detectors; for gas-specific monitoring, browse gas detectors. The SMCO100V-AC's advantage is covering both smoke and CO on one plug-in device.
Specifications
| Detects | Smoke and carbon monoxide (combination alarm) |
| Alert type | Voice alert announcing hazard type plus alarm horn |
| Power | Plug-in (AC outlet) with battery backup |
| Interconnect | No - standalone alarm (not interconnectable) |
| Applicable standards | Smoke per UL 217; CO per UL 2034 (combination) |
| Mounting | Plugs directly into a standard wall outlet |
| Brand / model | First Alert SMCO100V-AC |
Related Resources
CO detectors smoke detectors carbon monoxide alarms combination smoke/CO alarms gas detectors best CO detectors best smoke detectors CO detector placement guide how to test a smoke & CO alarm kidde kn copp b lpm battery carbon monox
Frequently Asked Questions
Does the First Alert SMCO100V-AC detect both smoke and carbon monoxide?
Yes. It is a combination alarm that monitors for both smoke and carbon monoxide on a single unit, so one device guards against fire and CO. Combination alarms meet smoke (UL 217) and CO (UL 2034) requirements.
How does the SMCO100V-AC get power?
It plugs into a standard AC wall outlet for continuous power and includes battery backup, so it keeps monitoring during a power outage. No hardwiring or electrician is needed.
Does it have a voice alert?
Yes. The 'V' in SMCO100V indicates the voice-alert feature, which announces whether the detected hazard is smoke or carbon monoxide rather than sounding a generic beep, helping you react faster.
Is the SMCO100V-AC interconnectable with my other alarms?
No. This is a standalone plug-in alarm and does not interconnect with other units. If you need alarms that sound together throughout the home, choose a hardwired interconnectable model or a wireless-interconnect alarm such as the First Alert CO511.
Where should I install a combination smoke and CO alarm?
Place alarms on every level of the home and near sleeping areas. Carbon monoxide mixes evenly with air, so CO mounting height is flexible. See our CO detector placement guide for room-by-room recommendations.
How is this different from the First Alert CO511?
The SMCO100V-AC is a plug-in combination smoke and CO alarm. The First Alert CO511 wireless interconnect carbon monoxide alarm is CO-only but links wirelessly with other CO511 units. Choose this model if you want both smoke and CO in one device.
How is this different from the First Alert CO250?
The CO250 is a battery-powered, CO-only alarm with a tamper-resistant cover. The SMCO100V-AC adds smoke detection and plugs into an outlet with battery backup. Pick the SMCO100V-AC for combined fire and CO coverage.
How long does a combination smoke and CO alarm last?
Sensors have a finite life: CO sensors typically last about 5-10 years and smoke sensors up to 10 years. When the unit reaches end of life, replace the entire alarm rather than just the battery.
Why do I need a CO alarm if I already have a smoke alarm?
Carbon monoxide is colorless and odorless, and a standard smoke alarm cannot detect it. A combination unit like the SMCO100V-AC adds a dedicated CO sensor so you're protected from both fire and CO poisoning.
Does the battery backup need to be replaced?
Yes. The backup battery should be changed periodically per the product instructions so protection continues during outages. Test the alarm monthly; our guide on how to test a smoke and CO alarm walks through the steps.
Can I use the SMCO100V-AC in a garage or attic?
No. Residential alarms are rated for living spaces. Garages, attics, and other unconditioned areas can hit temperature and humidity extremes outside the alarm's rated range, which can cause false alarms or missed events.
What other smoke and CO options does WC Safety carry?
Browse our full range of combination smoke/CO alarms, dedicated smoke detectors, and carbon monoxide alarms. For buying help, see our best CO detectors and best smoke detectors guides to compare models before you buy.
Written by Steven Eaton, WC Safety Editorial. Specifications sourced from First Alert published data. Compare the range in carbon monoxide & smoke alarms.
WC Safety is an independent PPE retailer and Amazon Associate; no paid placement. Match the product to your specific hazard and follow your site PPE program.
Brand / Vendor
First Alert
Model / SKU
SMCO100V-AC
Product Type
Smoke Detector
Condition
New
MPN
SMCO100V-AC
Price
$61.23 (Amazon)
Rating
4.38 / 5 — 8 reviews
Availability
✓ In Stock on Amazon
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Verified Buyer Reviews
Customer Reviews
★★★★☆4.4 / 5· 8 verified reviews
★★★★★
5.0 out of 5 stars
The installation of these was really easy with the plug adapters that came with it. I was replacing Kidde and FireX alarms that were in my place. One of the Kidde alarms was malfunctioning after I pressed the test button, so I don't trust that brand anymore. These are really loud, so I won't miss them if there ever is a real fire. I like the way you can select which part of the home the alarm is in during setup and it says that while the alarm is going off. I saw another reviewer saying that you're not going to be able to hear the name of the home announced in a real fire scenario. And meh, maybe maybe not. I like that these take the more common AA batteries over 9 volt. These seem to connect fine with the other First Alert alarms I installed. When testing, most of the other alarms sound as well, but not all. I'm not sure if that's because of wiring in the home or the alarms themselves. But I'm not too worried about that because even if two go off there is no way I am not hearing these, even behind closed doors. Now I haven't tested these with a real fire. I imagine smoke alarm manufacturers know that reviewers usually will not, so it behooves them to just make sure the setup process is really good, which it is with these alarms. If there ever is a real fire in my home I'll see about updating my review.
Anonymous · 2026-04-30 · ✓ Verified Buyer
★★★★☆
4.0 out of 5 stars
1 is defective but I only needed 5 of the 6. Those that operate, seem to work well. Troubleshooting included with the units did not help and was not accurate. Customer support, however, was very good.
Anonymous · 2026-04-30 · ✓ Verified Buyer
★★★★★
5.0 out of 5 stars
My old CO/smoke detectors were SC7010BV. These are the perfect match/replacement! Same base, same plug. At a bit over 10 yrs old the old ones started doing 5 chirps…end of life. BEFORE ordering these bought SC7010B on Amazon. I got shipped a substitute different detector that was smaller with a different plug! THIS is the right one to replace SC7010-BV! Also, easy to program the location before installing them. If/when they alarm or test, the voice on ALL say which one detected, which is great.
Anonymous · 2026-04-30 · ✓ Verified Buyer
★★★★★
5.0 out of 5 stars
Good updated replacement for my older units. Easy to plugin and put the new plastic brackets on. Wish they were less expensive on Amazon. Bought here due to overnight delivery .
Anonymous · 2026-04-30 · ✓ Verified Buyer
★★★★★
5.0 out of 5 stars
Having just moved into a new house with a finicky fire alarm in the kitchen? I did research, bought this one, and never looked back. The price was worth not hearing 15 false alarms while making a chili. The batteries have been stable between standard tests, and the one time someone decided to maybe accidentally let something kinda burn down too low and start smoldering? This alarm leapt into action, detecting the fault before the rest of the 'sensitive' system. The installation is dead simple. Switch out the collar or use it if you already have FA hardware made this century. The only way install could have been easier was sending someone.
Anonymous · 2026-04-30 · ✓ Verified Buyer
★☆☆☆☆
1.0 out of 5 stars
After 1.5 years, 2 of 6 have died with flashing lights indicating sensor failure. We also had numerous false alarms related to those two that failed. False alarms are traumatic for two reasons. One, these are insanely loud - you can't think straight when they go off and your ears are going to ring for hours afterwards - keep earplugs available so you can think better and troubleshoot a false alarm. Two, being interconnected, all alarms go off during a false alarm but its hard to tell which one is actually alarming. During a false alarm you have to go around and find the one that's flashing red, but if like me you have one in each bedroom and hallway then you have 4-5 going off all at once in a small area while they're all blaring at you. Hitting the silent button never worked maybe it silenced one alarm but all the others were still going off. One night during a false alarm I couldnt get them to stop and just started removing them from the ceiling and disconnecting power. So we have 2 of 6 that are dead and I don't want to use the warranty to replace them. I'd rather replace with a different brand that isn't so loud, and possibly with fewer false alarms and issues related to them. I'll never purchase First Alert alarms again. Update: Just before 2 years and a 3rd unit has failed with constant false alarms, even with brand new duracell batteries. That's a 50% failure rate, so far. These First Alert smoke alarms have made it so that I no longer trust these types of devices. I'd rather run with with nothing than play roulette with 2am false alarms that cause my ears to still ring with tinnitus a day later. First Alert makes absolute junk.
Anonymous · 2026-04-30 · ✓ Verified Buyer
★★★★★
5.0 out of 5 stars
We bought these to update our hardwired, interconnected system. This one especially for the laundry room, where our furnace and water heater are located. Works well with the 'regular' First Alert hardwired, interconnected smoke alarms. Easy to install, the base plate accommodates just about every form factor of ceiling mount. READ THE DIRECTIONS!
Anonymous · 2026-04-30 · ✓ Verified Buyer
★★★★★
5.0 out of 5 stars
I smoke and carbon monoxide detector worked as described by the manufacturer.
Anonymous · 2026-04-30 · ✓ Verified Buyer
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