How to Install Hard Wired Smoke Detector - Easy Installation First Alert Smoke Detector Model 9120B

How to Install Hard Wired Smoke Detector - Easy Installation First Alert Smoke Detector Model 9120B

Replacing a smoke detector can be really easy, especially with units like the one shown in this video from First Alert. What makes installation of these First Alert detectors easy is because they include wiring adapters for existing Kidde and FireX smoke detectors. That means if you have one of those two brands already in your home, this job is going to be a snap! But if you have to use the bare wire connector for your installation, stay till the end and I'll show you how connect the raw wires. So let's get started!

First, I'll turn off the power to the smoke detector in the room I'm working in. To remove this old Kidde unit, all I need is a quick clockwise turn to detach it from the ceiling. To remove the wiring harness, squeeze the side tabs and pull it straight out.

I won't be able to use the existing ceiling plate so just loosen the 2 screws holding it in and slide it off. Then separate the First Alert mounting plate and install this new one on the ceiling. The screw positions in the ceiling box are universal so this will slip on very easily. Then just tighten the 2 screws to secure it. But don't over-tighten them!

Wiring is really easy with the Kidde brand wiring adapter. It simply plugs into the existing connector coming out of the ceiling! If this was a FireX detector, I'd just use the other wire harness that came with the package. Before the new smoke detector goes on the ceiling, I need to insert the included 9 volt battery for backup. And I made sure I had the polarity correct before closing the battery tray.

The wiring harness now plugs into the back of the First Alert unit. Just make sure it's good and tight. Now align the detector with the ceiling plate and twist clockwise until it's secure. And that's pretty much it! Hopefully you're able to see how the installation with the included adapters made this super easy!

And if for some reason neither of those adapters work for you, here's how to connect this First Alert smoke detector by hard wiring it. I have to start by removing the old wire harness. And it's connected with wirenuts. Start by untwisting the wirenut on the black set of wires. And I'm just going to go one wire at a time starting with the black wires. Connecting this is easy by holding the bare ends of the wires together and attaching the wire nut. Be sure it's good and tight.

And then continue just like before with the white wire. The color coding on these wires are pretty easy to match up but I'm still going to detach and reattach these one at a time. And finally, connect the red wire. It's the same process on all the wires and it's safe to do when the power is shut off. When the red wire is detached I'm able to completely remove the old wiring harness. Then pull off the rubber cap and then connect it to the red wires coming out of the ceiling.

Last step is to stuff the wires into the ceiling box and connect the new smoke detector like I did before. Don't worry if you don't have any experience replacing a smoke detector! With the help of my instructions, I'm really confident you can do this yourself! Now just flip the breaker back on and it's good to go! I've also listed the exact First Alert smoke detector here in the description so it's easy for you to find!

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[MimisFoodieLife]

Your instructions were very clear. I think I will try to do it myself.

[ShereeBoley]

Great video-really appreciated the step by step to switch out the First Alert detector, especially the detail on connecting the wires at the end. We ended up making several trips up/downstairs to get all the tools we needed: extension cord to plug in a light, 2 different screwdrivers & plyers -couldn't get the caps off the original wiring. Don't think we could have handled this without your video! Thanks!

[qure]

Great video. This helped alot. I bought same brand smoke alarms from Costco and installed them using the very last method.

[mammacoal]

Thank you so much for this video! I'll be trying to replace and rewire 6 of these this week. I'll come back to let you know how I do :)

[m.p.]

Thank you!!! I needed exactly this video - especially the end with the rewiring part! Really appreciate this!

[eml]

THANK YOU!! Best Video on this smoke detector!! I've watch 3 other videos and the other ones, Ignored the Orange wire. A++

[D.Frasure]

Thanks for the schooling. I didn't know they come with adaptors, great!

[victoriamaile]

Thank you for your video. Watched a few wasn’t helpful, but yours was right on point. 👌🏽😅

[traceym]

what does it mean if the red light is flashing but the green power lightest degree

[bobpourri]

I suggest looking at a video showing the RIGHT way to connect wire nuts if you need to do that step. Also, the video does not explain how the red wire is used, and why it has a cap on it. HINT: When used, the red wires allow all the smoke detectors in the house to communicate with each other in the event any alarm goes off.

[dannygreen]

How do you remove the mounting bracket?? It doe snot just come off like in the video!

[johndbender]

uh, yeah...that little cap on the ORANGE wire does not just pull off like it does in the video. I had to cut it off, , , , PIA

[MarvinLindroth]

The orange wire tip did not slip off. I had to clip it off.

[dknc]

If you like me bought the dual package with the 2 in 1 CO alarm also, the adaptor is only packaged with one side of the alarm, so make sure you unpackaged both frustration packages and the adapters are on the left alarm side. I almost thought I don't have that adaptor at all. Also, mine has a 9V battery back up with a battery door locked as "DEFAULT" and was taped behind the factory label and a transparent film blocking the connection. It instructed to pull the transparent film off before use, but it's stuck in there so hard that you have to UNLOCK the stupid battery lock, open up the battery door and still struggle to pull that piece of transparent plastic out. What a stupid design and instructions. They should have highlighted that the door lock is LOCKED by default. Anyways.

[helenachase]

The battery set up for this alarm is c*** pure c***

[procellsearchlightpictures]

Smoke alarms (depending on the type) last 10 years. Not seven