Replacing a Hardwired Smoke Detector with a Battery Powered Detector

I’d like to replace the smoke detectors in my home with models that I can see in SmartThings (that is, the First Alert ZSmoke). I didn’t realize until I went to put the unit up that the existing smoke detectors are hardwired. I guess I never thought about it because the backup battery needed to be replaced once a year, anyway.

Are there any disadvantages to going to a battery-only unit? Could I just cut the power, cap and tape the wires, and put them in the ceiling? I read in the installation instructions that one shouldn’t replaced a wired thermostat with a battery thermostat because the air flow can cause it to not detect smoke properly… could I simply cut a piece of cardboard to put between the thermostat and the hole?

Would it be best to return these smoke detectors and wait for a wired version to come out?

Hey Kenneth,

I have the same issue, and am waiting for a wired one as well. Ill be curious if one ever exists though…

The nest protect has a wired version and they just released their API last week.

I would just cap the wires and put them in. I dont think youll have a detection problem. I definitely wouldnt put cardboard in there.

When in doubt test with some canned smoke

yes!! as soon as someone gets a device type for it, ill jump on two of them!

Eh, I’m not so much interested in the Nest products, or sharing all the data that it collects about my personal habits with Google. But, you definitely don’t think there’s a problem with just capping/stuffing the wires and putting the thermostats up as is, without trying to patch over the hole with something?

Frustrating enough, I’m reading now that hardwired is required by code in many areas. That’s a real shame if so, because it seems like the battery operated detector that connects to my phone via smartthings, reporting battery status, is as safe as if not safer than the hardwired detector.

I suppose there’s no harm with just installing the ZSMOKE alongside the hardwired smoke detectors in at least the two main hallways of our home. That’ll mean extra batteries to change every year, but that way, with only the added annoyance of a couple of extra screw holes in the ceiling, I could have the Z-Wave protected benefit and not risk falling out of compliance. Then, if and when there is a hardwired Z-Wave enabled smoke detector, I can replace all six in the house, proper.

I wrote some code for turning a MIMOlite into a hardwired smoke detector monitor.

heres my thread

You can also do it with an RS100HC.

Nick bailey did a device type for it;

Ive recently added some to it like consolidating the smoke and co into a single alert plus some cosmetic changes and more battery info and test report. I can post the code if interested.


My house is about 7 years old and all my smoke detectors are hardwired. I was able to contact the manufacturer (USI Electric) and purchase a relay module so that if any of the smoke detectors alarm, I can send a signal to an external device. Now I just need to find some code for the MIMOlite so it will appear as a smoke detector.