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.
Through early warning interconnect, when one alarm sounds, all compatible alarms will sound
Battery backup provides continuous protection during power outages
Alarm indicator visually identifies the unit that initiated the alarm
Quick Connect Plug included allows for easy installation with no need to rewire
Specification: First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack
Brand
First Alert
Style
Precision Detection
Power Source
Battery Powered
Color
White
Product Dimensions
5.6"D x 5.6"W x 1"H
Item Weight
9.6 ounces
Alarm
Smoke Alarm
Sensor Type
Ionization
Global Trade Identification Number
10029054022469
Number of Items
1
Manufacturer
Resideo
UPC
029054022462
Part Number
SMI100-AC
Item model number
SMI100-AC
Size
1-Pack
Pattern
SMI100-AC
Item Package Quantity
1
Included Components
Easy Adapter Plug, 9V Alkaline Battery
Batteries Included
Yes
Batteries Required
Yes
Battery Cell Type
Alkaline
Date First Available
September 22, 2023
6543 reviews for First Alert SMI100-AC, Hardwire Interconnect Smoke Alarm with Battery Backup, 1-Pack
4.6out of 5
★★★★★
★★★★★
8
★★★★★
1
★★★★★
0
★★★★★
0
★★★★★
0
Write a review
Show allMost HelpfulHighest RatingLowest Rating
★★★★★
RBNetEngr –
Smoke alarms should be replaced after ten years. My home was built with First Alert smoke detectors, a total of EIGHT! I purchased these and the electrical connector they use is the same as my original smoke detectors. I just had to disconnect the old detector, then replace the plastic trim ring and the detector. It took less than five minutes per detector, including moving and climbing the ladder.
These detectors work exactly as the old ones did, and if one detector alerts all of the others will alert as well. When they are powered up they emit a soft green glow so you know they are powered up.
Buying them on Amazon saved me over $100 versus purchasing the same product at Lowes or Home Depot.
Helpful(0)Unhelpful(0)You have already voted this
★★★★★
ROCCO C –
I recently installed the First Alert SMI100-AC Hardwire Interconnect Smoke Alarm throughout my home, and I’m really impressed with its performance and ease of use.
Installation was straightforward. The unit is designed to be hardwired, and it also includes a battery backup, which gives added peace of mind during power outages. It integrates well with other First Alert alarms, so if one goes off, they all do — exactly what I was looking for in an interconnected system.
The alarm is loud and clear, which is essential for ensuring everyone in the home is alerted quickly in an emergency. The test and silence buttons work as expected, and the indicator lights are easy to understand (green for power, red for alarm/test).
What I particularly appreciate is the build quality. It feels solid and well-made, not flimsy like some other brands I’ve tried in the past. If I had one minor critique, it would be that the instructions could be a bit more detailed for first-time installers. If you have older Wired Smoke Detectors you may need an electrician to connect the new connector if you are not comfortable do that work yourself
Overall, this is a reliable and well-built smoke alarm that offers great protection for your home. I highly recommend it!
Helpful(0)Unhelpful(0)You have already voted this
★★★★★
steve –
Easy to replace the Kidde.
Looks new and modern and is very easy to install especially if you’re familiar with wire nuts and have some at home.
If not, they’re cheap at your hardware store. Use orange color wire nuts for the wires leading to the smoke alarm.
Watch YouTube video on how they work. Very simple.
Helpful(0)Unhelpful(0)You have already voted this
★★★★★
Mark –
Good as replacement or new smoke/carbon monoxide alarms. I’ve been slowly replacing mine as my original ones are 10 years old and are slowly going out (end of lifespan) and the fit right in where the original ones were. Easy to connect and mount with a loud alarm. Simple but effective functionality.
Helpful(0)Unhelpful(0)You have already voted this
★★★★★
Juan Diego Rojas –
I purchased the First Alert SA9120BPCN smoke detectors to replace older ones in my home, and I’m extremely happy with the results. Installation was quick and easy—they connected perfectly to the existing wiring and mounting brackets, which saved a lot of time.
What I love most is the interconnect feature—when one alarm goes off, all of them sound. This adds an extra layer of safety, especially in multi-room or multi-level homes. The alarm is loud and clear, and the test button works perfectly. It’s also great to know that this product comes from a trusted brand like First Alert.
If you’re looking for dependable smoke detectors that are easy to install and provide peace of mind, this is a great choice. Highly recommended.
Helpful(0)Unhelpful(0)You have already voted this
★★★★★
Joseph Belanto –
Easy to install. However, the 3-pack did not include any quick connect plugs, which is how I was planning to install them. However, a set of connectors can be purchased separately, which is what I did. They seem to be working great. The constant green light indicating proper AC connectivity might be annoying depending on placement, but it doesn’t bother me.
Helpful(0)Unhelpful(0)You have already voted this
★★★★★
CSApopka –
Bought these to replace the original smoke detectors because they were over 10 years. Good value for the money, easy to install and offers a peace of mind.
Helpful(0)Unhelpful(0)You have already voted this
★★★★★
pellethead –
Why did you pick this product vs others?: competitive price, value and compatible with other first alert alarms on interconnection. easy to install. disconnect the breaker for the smoke alarm circuit in your main electrical box. next simply connect the color of each wire to the same in the ceiling receptacle. then pull out the plastic tab to energize the backup battery. finally return to the main box and turn on the breaker. all the installed alarms will display a green LED.
Functionality: interconnects with my other first alert alarms.
Helpful(0)Unhelpful(0)You have already voted this
★★★★★
Frank P. –
installed and has been working fine, no problems or issues
Hybzone
RBNetEngr –
Smoke alarms should be replaced after ten years. My home was built with First Alert smoke detectors, a total of EIGHT! I purchased these and the electrical connector they use is the same as my original smoke detectors. I just had to disconnect the old detector, then replace the plastic trim ring and the detector. It took less than five minutes per detector, including moving and climbing the ladder.
These detectors work exactly as the old ones did, and if one detector alerts all of the others will alert as well. When they are powered up they emit a soft green glow so you know they are powered up.
Buying them on Amazon saved me over $100 versus purchasing the same product at Lowes or Home Depot.
ROCCO C –
I recently installed the First Alert SMI100-AC Hardwire Interconnect Smoke Alarm throughout my home, and I’m really impressed with its performance and ease of use.
Installation was straightforward. The unit is designed to be hardwired, and it also includes a battery backup, which gives added peace of mind during power outages. It integrates well with other First Alert alarms, so if one goes off, they all do — exactly what I was looking for in an interconnected system.
The alarm is loud and clear, which is essential for ensuring everyone in the home is alerted quickly in an emergency. The test and silence buttons work as expected, and the indicator lights are easy to understand (green for power, red for alarm/test).
What I particularly appreciate is the build quality. It feels solid and well-made, not flimsy like some other brands I’ve tried in the past.
If I had one minor critique, it would be that the instructions could be a bit more detailed for first-time installers. If you have older Wired Smoke Detectors you may need an electrician to connect the new connector if you are not comfortable do that work yourself
Overall, this is a reliable and well-built smoke alarm that offers great protection for your home. I highly recommend it!
steve –
Easy to replace the Kidde.
Looks new and modern and is very easy to install especially if you’re familiar with wire nuts and have some at home.
If not, they’re cheap at your hardware store. Use orange color wire nuts for the wires leading to the smoke alarm.
Watch YouTube video on how they work. Very simple.
Mark –
Good as replacement or new smoke/carbon monoxide alarms. I’ve been slowly replacing mine as my original ones are 10 years old and are slowly going out (end of lifespan) and the fit right in where the original ones were. Easy to connect and mount with a loud alarm. Simple but effective functionality.
Juan Diego Rojas –
I purchased the First Alert SA9120BPCN smoke detectors to replace older ones in my home, and I’m extremely happy with the results. Installation was quick and easy—they connected perfectly to the existing wiring and mounting brackets, which saved a lot of time.
What I love most is the interconnect feature—when one alarm goes off, all of them sound. This adds an extra layer of safety, especially in multi-room or multi-level homes. The alarm is loud and clear, and the test button works perfectly. It’s also great to know that this product comes from a trusted brand like First Alert.
If you’re looking for dependable smoke detectors that are easy to install and provide peace of mind, this is a great choice. Highly recommended.
Joseph Belanto –
Easy to install. However, the 3-pack did not include any quick connect plugs, which is how I was planning to install them. However, a set of connectors can be purchased separately, which is what I did. They seem to be working great. The constant green light indicating proper AC connectivity might be annoying depending on placement, but it doesn’t bother me.
CSApopka –
Bought these to replace the original smoke detectors because they were over 10 years. Good value for the money, easy to install and offers a peace of mind.
pellethead –
Why did you pick this product vs others?:
competitive price, value and compatible with other first alert alarms on interconnection. easy to install. disconnect the breaker for the smoke alarm circuit in your main electrical box. next simply connect the color of each wire to the same in the ceiling receptacle. then pull out the plastic tab to energize the backup battery. finally return to the main box and turn on the breaker. all the installed alarms will display a green LED.
Functionality:
interconnects with my other first alert alarms.
Frank P. –
installed and has been working fine, no problems or issues