Two story building, first floor contains a Subway resturant and used furniture shop. Second floor is a three bedroom appartment. I have been requested to install smoke detectors in all three spaces with the requirement that all sound if any one unit "smells" smoke.

I have used three wire smokes many times, no sweat in a single residence where one circuit powers the entire loop.

Can I tie three different circuits to a single alarm loop using "conventional" three wire smokes? I can't see how and would appreciate some help.

Thanks, Takideezy