Is this smoke detector safely connected


I recently bought this house (built in 2000), so it went through inspection. I assumed everything was fine. I realized the smoke detector in one of the rooms was not showing the green light that the others were showing. I pressed the "test" button and it beeped just like the others, so I thought it may be okay.

More recently I decided to actually take a look at it, and figured out the black wire is completely disconnected. Googling what that wire means gave me different results, but most of the results suggeste the detector would not be connected to the power, which would mean its battery would end very quickly, but I don't see the detector complaining about the battery (it's been a few months since we moved in).

Now I'm completely confused and have no idea if this is actually safe (especially since the home inspector was supposed to have checked this).

Am I safe? Would it be easy to fix this in case there's a problem? The other detectors in the house are not connected like this one.

See the picture here


Best Answer

This is a Firex 4618, interconnected smoke alarm with backup battery. Here is the manual which explains Green Light means its operating on A/C (hardwired) power. Otherwise, its running off the backup battery. It can run on the backup for several years like a battery operated smoke alarm, but the manual states a standard battery should last for 1 year, then when it drops under voltage it will chirp at you.

The black wire (hot) can be connected to a black wire up in the box to run on A/C power again. Often it can pop off especially if someone removed the smoke detector that strained the wires. Those stranded core wires and cheap wire nuts that come with the smoke detector often don't result in a very strong connection.

The fix is to first switch off the power. Hard wired smoke alarms usually share the lighting circuit. Then you can reconnect the black wire on the pigtail to the black wire in the box. When you power it back on, there will be a green light like the others.