Onelink Wireless Hardwired Smoke Alarm
Wirelessly interconnect alarms. 120VAC hardwired wireless interconnect smoke alarm with battery backup. To expand protection to include both existing hardwired alarms and new wireless alarms, simply replace one existing hardwired alarm with Onelink, then add Onelink battery operated alarms elsewhere and when one alarm in either series alarms, all alarms will be notified. Easily link alarms together with the press of a button. When one alarm sounds, they all sound for maximum whole home protection. Photoelectric smoke sensor reduces nuisance alarms from cooking smoke or shower steam. Easy access battery drawer: no need to remove alarm from ceiling to change battery. 10-year limited warranty. Meets UL standards.
This ONELINK wireless alarm is for you if:
● You want to build a safety network of interconnected alarms in your home without the cost and hassle of wiring.
● You want to your existing hardwired alarms to communicate with new Onelink wireless alarms to expand protection.
Where To Place Smoke Alarms: One on every level of the home and one in each sleeping area.
First Alert Smoke Alarm SA521CN-3ST
Onelink Wireless Hardwired Smoke Alarm Features:
● Wireless interconnectivity, wirelessly connect up to 18 Onelink alarms in your home and when one sounds, they all sound for increased whole-home protection.
● 120v ac hardwired, easily replace one existing hardwired alarm with Onelink SA521 and then add Onelink battery operated alarms to connect wireless alarms with hardwired alarms--when one sounds, they all sound.
● Battery backup, provides consistent protection for added safety during power outages.
● Photoelectric smoke sensing, optimal protection from smoldering fires. plus, reduces false alarms like those caused by cooking fires and shower steam.
● Mute button, mutes unnecessary alarms immediately. also tests alarm function with same button.
● Eco-friendly, completely recyclable as an electronic device.
● EZ access battery door, no need to remove alarm from ceiling to change battery.
● Optional theft-prevention lock, when activated, batteries and/or alarm cannot be removed without proper tools.
● 2AA batteries included.
● Loud 85db alarm.
● 10-year limited warranty.
● Smoke alarms should be replaced every 10 years for maximum protection.
● Meets UL217 standard.
● FCC compliant.
Review this product




average customer rating based on 12 reviews




Intergrated System - 01/26/2012
Reviewer: James Dunkel
I just updated teh entire Smoke, Carbon Monoxide and Heat garage alarm system in my 90 year old house. Part of the total system is hard wired and part is not. The One Link system enabled me to have an intergrated system and provide a higher level of warning. I am very happy with the system. It is very important to watch the video on how to link the products.




Safe Family - 11/23/2011
Reviewer: Justin Slate
First Alert allowed me to put my familys safety first




Excellent Product - 11/22/2011
Reviewer: Jim
I would highly recommend this product to anyone with multiple floors. Never thought much about not being able to hear the one in the basement until I discovered this model of smoke detector. Now the one upstairs will go off as well.




Who designed this? - 11/20/2011
Reviewer: Dan Dobkin
First of all, we havent had a fire so I cant speak to whether this device performs its intended function well. But ... the backup batteries always die in the middle of the night when it is cold. Whoever thought of having something beep every minute has obviously never used the device. Once awakened, it is impossible to sleep so you have to fix it once you figure out which one it is--also a pain in the neck. Standing on a chair with the lights off because the rest of the family is still asleep at 2 AM, it is virtually impossible to open the battery compartment without removing the unit from the twist-on mount. In my case this caused a ground wire to come loose, whereupon all the alarms in the house decided they had to scream a non-silenceable alert at 85 dB. This is not entertaining at 2 in the morning. Spouse and child were not pleased.
REDESIGN THE ALERT: it should go off once an HOUR so you can ignore it at night but deal with it during the day, stay on long enough to be located, AND be associated with a flashing POWER light so you can be sure you got the right one.
It wouldnt hurt to make the battery compartment possible to open without a screwdriver. It doesnt slide for squat.
Just for the record I hold a PhD in applied physics and work as an electrical engineer, and no, that doesnt make it possible to guess what your one-button control is supposed to do.
eAccess Response:
We have relayed your concerns to First Alert. Thank you for posting this review.




GREAT PRODUCT - 08/01/2011
Reviewer: Partne Daugherty
I need to interlink 5 hardwired smoke detectors via wireless means in a mobile home to pass local code enforcement insoection. Being a doublewide mobile home, the electrician could not climb into the attic, so we used the ONE Line hardwired smoke detectors to accomplish the job.




- 07/05/2011
Reviewer: Sharon Church
Very easy to install.




One correction to my review above - 05/26/2011
Reviewer: Don M
In my review above, I mentioned that First Alert should offer a PDF version of the instruction manual. They do, in fact, offer a PDF version of the manual on the FirstAlertStore.com site - I was looking on the main FirstAlert.com site. It would be nice if you could get it from both sites though. Anyway, just click on the Manual tab and there is a link to the manual duh.




Easy to install and work great - 05/26/2011
Reviewer: Don M
I bought four Onelink Wireless Hardwired Smoke Alarms SA521CN-3ST to replace the original smoke detectors that were installed when our house was built 20 years ago. The Onelink units were easy to set up and easy to install. Once they were installed I tested all four detectors separately to be sure that they were communicating with the other three units and they all performed great in testing. I have two in the basement, one on the main floor and one on the upstairs floor and they have no problems communicating. I have had them installed for two weeks now and so far no false alarms. Hopefully I will never have to find out how they work during a real fire. I plan to add at least one more non-hardwired battery operated unit in our hot water heater room in the basement which did not originally have a smoke detector and also possibly add battery operated units to each bedroom as well. One small criticism I would give is that the printing in the instruction manual was very small - I have 20/20 vision, do not wear glasses, and had difficulty reading the printing. It would be nice if First Alert offered PDF versions of the instruction manuals online to make them easier to read. One extra piece of advice I would give for anyone installing a new smoke detector is to keep the screws to your old smoke detector handy - these units only come with drywall screws and anchors and my original detectors were connected to junction boxes since housing codes at the time my house was built required all smoke detectors be connected hardwired with a battery backup, so I had to re-use the original screws that were connecting the detector to the junction box, which was no problem at all - just thought Id give anyone else in the same situation a heads up to hang on to those screws.




Works Fine - 05/19/2011
Reviewer: Robin Corsiglia
Seems to work fine. It did link to my other smoke alarms.




- 04/21/2011
Reviewer: Robert Martin
Needed to be voice, simular to the wireless battery only detectors




Onelink - 04/13/2011
Reviewer: Kenneth Johnson
I have a hard wired system and wanted to add additional units to it. This unit enabled me to add additional battery operated Onelink units and interconnect all of our sensors




- 04/09/2011
Reviewer: Bill Pelino
very easy to install and connect with other devices