I am looking for a solution that would make the wired smoke detector in the apartment downstairs trigger an alarm. The purpose is to be alerted if there is smoke while the tenant is away/in the shower.

At the moment, the smoke detector downstairs is connected to another smoke detector in my own space. It works, but the detector downstairs also goes off if I burn toast, disturbing the tenant downstairs.

I am looking for a way to replace that wired detector in my place with a simple alarm, since it is it's actual purpose. A solution using a piezo is proposed in a comment here but there are no details on how to procede.

Another possibility would be to neuter the detector part in my unit and use it for its alarm only, but I don't know if that is doable.

1 Answer 1


It goes without saying you'll want to follow the manufacturer's instructions to the letter, as well as all relevant electrical, fire, and building codes that apply from both a safety perspective and a compliance / legal perspective. Fire alarms are no place to get creative.

With that said, you may be in luck - if your smoke detectors are compatible with it, Kidde makes a relay module that does exactly what you want:


This module is only activated by a smoke alarm interconnect signal. The relay portion of this module can be used to activate auxiliary warning devices such as external bells and sirens, hallway or stairwell lighting. It provides isolated, (no internal connection to 120 volts AC) normally open, and normally closed contacts.

It should be possible to replace the upstairs smoke detector with this module and a bell or siren.

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    There are also wireless units that talk to each other, we recently put a pair in an apartment for the same reason. (But that place did not have wired units) they were ~40 each but this provides a warning for the folks on the upstairs floor if there was a fire downstairs. They were photo electric & carbon monoxide. The voice alarm identify the triggered location. Photo electric do not trip as easily as an imbalanced ion chamber so there would less false alarms from cooking. The units we purchased were first alert we only purchased 2 for now but I think up to 16 can talk but don't remember.
    – Ed Beal
    Jan 28, 2019 at 14:56
  • I'm gonna go with the relay module + piezo, in an abs box fixed in a discrete spot. The relay module has very detailed documentation on how to do the connections.
    – GuillaumeL
    Jan 29, 2019 at 0:01

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