Whole House Smoke Alarm Integration

Anybody done this? I have a whole house smoke alarm system it is hard wired 120v with 9v back up. They are wired using 14-3… the red wire is what is used to signal the other alarms to go off.

Does anybody know if the switch leg uses 9v or 120v? I am thinking that it should be easy to tie a mini relay to the common and switch leg combined with and everspring window sensor this should be able to allow your smoke alarm system to show up as a sensor.

In theory you could also use a relay to trigger the alarms if someone breaks in.

probably uses 9v but to make sure you’re better off taking a multimeter and measure the voltage. good idea using this for alarm sirene. could also attach a electric magnet to it and have this trigger the window sensor.

Kidde has a relay module for their wired smoke alarms… This might be the better solution than rigging something into the system…

I used the Kidde SM120x and did exactly this. I followed these instructions and it works perfectly:


The Kidde relay can be configured to trigger the alarms although I didn’t set mine up this way.

Use a device to interface to the RED wire … If you put a 9 volt relay on that line … and it draws to much current … it will not signal all of the other detectors. A sink device should NOT sink much current.

When you put a 9 volt signal ON the red (White wire is 9 Volt Common) wire it will provide the signalling power to trip the other sensors.