Why Is the Green Light Blinking on My Smoke Detector: LED Alarm Tips

Not so long ago, homes didn’t typically have smoke detectors installed. Every residence has one these days, and it’s vital to know where it is and details like why the green light is blinking on your smoke detector.

It may seem like a small and virtually insignificant piece of equipment until it starts screaming at you. However, those little smoke detectors are crucial warning systems. In 2019 alone, there were three-hundred-sixty-three-thousand house fires.

That’s a lot of damage, and you can bet that tens or hundreds of thousands of lives were saved by these clever, compact warning systems. However, your fire alarm will not work if the batteries are low, or the power is gone. Hence paying attention to blinks and beeps is a necessity plus it could indicate power status problems.

I will explain how most smoke detectors work and what the blinking lights signify so you’ll know what to do to stay safe. Forewarning is everything when fires happen. 

Why is the green light blinking on my smoke detector? A blinking green light on your smoke detector means your batteries are low. The green light will flash off and on at different intervals depending on the model of the smoke detector.

Here is a chart that was derived from a manual by First Alert showing the different green led lights flash intervals for specific models of First Alarm smoke detectors when the battery needs to be changed:

First Alert Model NumberIntervals of Flashing Green Light
3120Bflashing every 2 seconds
SC7010Bblinking on and off
SC9120Brapidly flashing green light
SC05CNblinking on and off

Honeywell Smoke Detector Flashing Green

If you have a Honeywell smoke and heat detector, here are the situations where the green will blink:

  1. when the unit is first powered up, such as when you install the battery.
  2. the green light will flash every 10 seconds when it is in the standby or normal mode.

BRK Detector Green Led Lights Turns off and on

For the BRK models 9120 and 9120B, the green light will go off for 2 seconds, and the on for 2 seconds once the smoke level has decreased to the point where the alarm stops. Nevertheless, it does mean that you still have a working smoke detector.

Are Smoke Detectors Supposed to Blink

When you see the green light blinking on your smoke detector, it’s normal to wonder why. Are smoke detectors even supposed to blink? More importantly, should you be worried? Blinking isn’t a sign of a fire, nor is it an indicator of CO2 gas, so why would it even matter?

Smoke detectors have two ways to warn you that something is wrong, other than a fire or carbon dioxide warning


  1. Most smoke detectors are designed to give off a single beep every thirty to forty seconds. You can often hear these things going off in the background of calls and even videos on social media. It means the person on the other end doesn’t realize there’s a problem. 
  2. The second way a smoke alarm warns you is by blinking when it beeps. This helps people identify the source of the problem and makes it easier for people with hearing impairments to see that the alarm is out of power. All it means is that you need to change the battery so it is a warning that your battery is getting low. 

I recommend that First Alert Dual-Power Carbon Monoxide Detector Alarm that is available at Amazon. 

New Smoke Alarm Blinking or Flashing

When you first install some models of smoke alarm, they blink in rapid succession. Just like the low battery warning, this is supposed to happen. However, those blinks are not a sign of trouble, nor should you worry about them.

A new smoke alarm blinks to indicate it is connected to power. Even an older smoke alarm may do this if you disconnect and reconnect it or put new batteries inside. Those blinks are like the boot-up noise on your desktop computer, an indication that all is well, and things are functioning the way they should. 

What Color Should the Light Be on a Carbon Monoxide Detector

Newer carbon monoxide detectors have a separate set of led lights than standard smoke alarms. Even those models that do both jobs (smoke and CO2) should have green, yellow and red lights. When the green light is blinking on your carbon monoxide detector, it means all is well, and the device is working. Your CO2 monitor light should always be green.

Also, if the carbon monoxide detector’s green light stays on, it also means that the detector is fine.

Alternately, when you see a flashing yellow light, it indicates some type of trouble. Either it’s time to change a battery, as indicated by a battery logo on the LED screen, or it means there’s a low but noticeably higher than normal amount of CO2 in your home. The latter case may mean you need to open a window and air things out, or it can be a warning that something is in the process of going wrong. 

The red light on a carbon monoxide detector means big trouble. If your CO2 device is flashing, you need to get out of there. It doesn’t take a lot of carbon dioxide to cause sickness, dizziness, fatigue, and other symptoms. More importantly, too much carbon dioxide can kill you. 

When you inhale CO2, it fills the same spots that regular oxygen would in your circulatory system. However, it does not give you the oxygen you need to survive. By blocking necessary oxygen uptake and refusing to give up the oxygen molecules, carbon dioxide becomes deadly quickly.

You can breathe in all the CO2-filled air you want and still suffocate slowly because it stops your body from getting the oxygen-rich air you need to survive. 


Why Is The Red Light Flashing On My Smoke Detector

Now you’ve installed your smoke alarm, the batteries are new, and yet that little red light is going off every minute. It’s not a green light, so should this be blinking on your smoke detector.

The simple answer is yes. If your smoke alarm has new batteries or is wired into running power, and all else seems fine, then your model uses a red light to indicate it’s working correctly.

So long as you do not hear a beep with flashes, you are simply fine. The light will flash once per minute to let you know it is doing the job for which it was designed. 

The X-sense Smoke and Carbon Monoxide Alarm from Amazon has a ten-year battery and a ten-year sensor. Since it’s not hardwired, this is incredibly useful. The LCD is easy to read and gives you the practical information you need. Best of all, the easy to install X-sense is certified to meet the UL 217 & UL 2034 safety standards. Read the exceptional reviews by clicking here. 

Why Is My Smoke Detector Blinking Red Every 10 Seconds

A smoke detector that is blinking red every ten seconds has detected smoke. Usually, by the time this occurs, it has already sent an alarm and stopped ringing. What this means is that the smoke is not very dense. If you burned dinner, then it’s nothing to worry about. Open a window and let the fresh air in.

Otherwise, you may have a small fire somewhere in the house. Smoke detectors rarely, if ever, send false signal flashes. There will always be some source of smoke. In dual fire and CO2 alarms, it could be a carbon dioxide warning, but there is a problem, albeit the alarm doesn’t think it is quite as serious as a ‘get out right now’ warning. 

Why Is The Green Light Off on My Smoke Detector

As alarming as a light going on, when your smoke detector’s light goes and the flashes disappear, it can indicate an issue. Why is the green light not blinking on your smoke detector? More importantly, does it mean you’re in danger or that you need to replace the smoke detector? 

First, take a deep breath. It’s going to be fine. Your smoke detector has a problem, but it’s not an immediate danger to you. According to Universal Security, ” The AC power has been interrupted. Check the circuit breaker and AC wiring to correct the problem.” 

Also, if the power goes out in the hardwired smoke detector, at the online store for First Alarm, it is stated that the backup battery will ensure that the alarm will go off if there is a fire or smoke. Nevertheless, if the battery is weak, it will only be monitoring for problems for about a week.

Typically, this only happens on wired-in smoke alarms. A wire came loose or broke. It could also mean the power is out, and the device isn’t getting the power it needs. The simple solution is to check for detached, bent, stripped, or broken wires and replace them. 

There is a Kidde Photoelectric Smoke Detector is hardwired. To learn all about Kidde, click here. 

Final Thoughts on Flashes of Green On Smoke Detectors

Although they’re easy to forget when they sit silently on the wall for months or years, your smoke alarm and CO2 detector is one piece of lifesaving equipment you should never ignore. If your smoke detector has flashing lights, you need to change the battery. However, it is always wise to look up the instruction manual for your model. 

A simple battery change is nothing until you don’t do it. Every year thousands of people die in house fires. Most upsetting of all is that many of those deaths could have been avoided with a good smoke detector with fresh batteries. 

Always pay attention to your smoke alarm. Whether it’s blinking, beeping, or screaming an alarm at you, this is one little round plastic device that should never be ignored. 

Related Topics

first alert smoke detector green light blinking

Aron Blake

I am the lead copywriter on Homezesty and the Webmaster. I have a lot of experience in home renovations and the creation of style. I enjoy writing and sharing my tips on how to create the best living environment. My Linkedin Profile, My Twitter Account

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