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The First Alert SA521CN-3ST Interconnected Smoke Alarm allows owners to create an interconnected fire alarm system without the cost and hassle of wiring. Use this smoke detector to replace an existing hardwired smoke alarm and then install additional First Alert Wireless alarms for an interconnected safety network (additional alarms sold separately). This hardwired smoke detector can connect and communicate with up to 18 compatible alarms, so when one alarm is triggered, the entire system reacts. An integrated battery backup ensures the smoke alarm continues to work even during power outages.
Photoelectric Sensor Warns of Smoldering Fires
The First Alert Wireless Interconnect Smoke Alarm comes equipped with a photoelectric sensor to provide the earliest possible warning of fire. The sensor is optimized to detect larger smoke particles produced by smoldering fires, such as those caused by unextinguished cigarettes. It also distinguishes between real threats and smoke/vapor produced during showering, cooking, and other everyday activities, helping minimize the number of false alarms. A patented smoke entry system helps ensures reliable detection by providing a direct air pathway to the sensor.
Interconnectivity for Larger Areas
The hardwired smoke alarm can be connected to other compatible BRK and First Alert hardwired alarms for larger buildings such as dormitories, office buildings, and apartments. Connect up to 18 compatible devices: up to 12 smoke alarms and six compatible devices like horns and repeaters. The communication distance (range) between any two First Alert Wireless Interconnect Alarms is typically 50 ft. (15 meters) inside of a home. Some features of a home, such as the number of floors, number/size of rooms, furniture and types of building materials used may reduce the range of wireless interconnect alarms. First Alert helps you create a comprehensive warning system for you and your property.
Battery Backup for Continuous Coverage
In the event of a power outage, the smoke alarm is still able to function thanks to its two AA backup batteries. An indicator sound is emitted when the batteries need to be replaced. The inclusion of an optional drawer and mounting bracket lock will discourage tampering.
Test and Silence Button
Mute Button has been included to serve the dual purpose of silencing nuisance alarms and testing the functionality of your alarm.
EZ-Access Battery Door
The addition of an EZ Access Battery Door removes the hassles and burdens associated with changing your alarm's batteries.
First Alert Wireless Interconnect Hardwired Smoke Alarm SA521CN-3ST
In this guide, we'll be showing you how to install First Alert Hardwired Smoke and Carbon Monoxide Alarms. Here are a few items you'll need before starting the installation process: Needle-nose pliers or utility knife, screwdriver, wire stripper, wire nuts and a ladder.
Hardwired Smoke or Carbon Monoxide Alarm Requirements:
To begin, turn off power at the junction box and connect your alarm to the building's electrical wiring.
|Attach to black wire on power connector|
|Attach to white wire on power connector|
Standalone (single-station) alarm: This wire is not needed; tuck the orange wire into the junction box.
If you are installing more smoke or carbon monoxide alarms, you'll want to repeat the process throughout the building. Interconnected smoke and co alarms must meet all requirements:
The same fuse or circuit breaker must power all interconnected alarms.
Up to 18 compatible detectors can interconnect, with a limit of 12 smoke alarms.
The total length of wire interconnecting the alarms should be less than 1,000 ft. (300 meters). This type of wire is commonly available at hardware and electrical supply stores.
All wiring must conform to all local electrical codes and NFPA 70 (NEC). Refer to NFPA 72, NFPA 101, and your local building code for more information.
Interconnect wiring diagram:
If you have any doubts or reservations about these interconnect requirements, please contact an experienced electrician to install your wiring and hardwired alarms.
Once you've installed your hardwired alarms, you'll want to restore power to the junction box. Under regular operation, the power indicator light on the alarm will shine/blink to indicate that it is receiving AC power.
Here's how you can test standalone or interconnected alarms:
Standalone Alarms: Press and hold the Test/Silence button until the unit triggers an alarm.
Interconnected Alarms: Press and hold the Test/Silence button until the first unit triggers an alarm. All interconnected detectors should sound off. Repeat this process to test each alarm in the interconnected series.
Other reasons include: It could be a different device or appliance such as a security system, monitor, carbon monoxide alarm, or other device which has a similar low battery or alert signal. Some of the same factors that cause unwanted alarms can cause intermittent alarms: dust and insects in the alarm or power interruptions in hardwired alarms. Improper wiring on AC or AC/DC smoke alarms. AC alarms will chirp every 5 seconds if the interconnect wire is grounded. The orange interconnect wire should NEVER be grounded; it should only be used to interconnect other smoke alarms or compatible devices.
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Average score based on 48 reviews
- Reviewed: 05/06/2022 by Patrick K
Devices arrived promptly and in good order the day after they were ordered. Installation was easy using the web site and the included instructions. Thanks First Alert.
- Reviewed: 04/26/2022 by Kenneth J
They work great easy set up only downside is that they are bulky seem huge
- Reviewed: 04/28/2021 by Francis M
The product was put into operation this past weekend. The system puts together two separate buildings into one . A quick sinking with the help of a technician , was a breeze. Thank You ! Frank MCQUADE. a combo, a Smoke & CO system would be great
- Reviewed: 05/19/2020 by Tom Bijak
Works as advertised. Shipped as promised.
- Reviewed: 12/20/2019 by Shirley Hufford
This item did what was expected. It allowed us to connect all of our wireless smoke and carbon monoxide detectors together.
- Reviewed: 09/25/2018 by Alan Del Rossa
Tested good. Synced to other smoke alarm.
- Reviewed: 05/31/2018 by Bryan
It was easy to install since we had older BRK / First Alert units. Connected with the other units flawlessly.
- Reviewed: 01/05/2018 by William Rogers
This product installation is quick and easy. The set up is very labor efficient. This product is loud and will notify you immediately. This is a very good system and needs to be put out to people to let those know about it without alarm systems. Pricing is very reasonable.
- Reviewed: 05/15/2017 by Thomas Piorkowski
Expanded Home System
I had old smoke alarms that I wanted to replace: 2 upstairs, 1 main floor and 1 in the basement. Three I replaced with combo smoke/CO2, the 2nd upstairs unit I purchased a bridge unit to connect the old hard wired to the 4 new battery units. The hardest part was the wired units because the old connectors didn't match any brand of new unit. The detectors came with easy directions and it wasn't that hard. Once set up, all work perfectly together. I like the voice indication, telling you where the fire or co2 issue is located. I am very pleased with the purchase and feel more comfortable with my expanded zone. No extra cost for wiring so although the units are a little more expensive it doesn't cost as much as an electrician!
- Reviewed: 05/15/2017 by rick christoffersen
Hardwired systems seamlessly integrated with the multiple First Alert wireless smoke alarms we installed. Now all alarms are integrated throughout our home. Awesome!