Hey guys...hows it going, been on vacation
I agree with Active 1 and his statement regarding the rules pertaining to hard wired smoke detectors that are not supervised. NFPA 72 1999 edition, section 8-1.4.4 specifically limits the number to 18 initiating devices (of which 12 can be smoke detectors)
Wirenuttt...it is not practical to interconnect the smoke detectors of one dwelling unit to another dwelling unit.Every time the occupant of one unit overcooks something in the kitchen, other people in the building would be be disturbed by the nuisance alarm.
Electricmanscott pointed out how Massachusetts requires a heat detector to be installed not more than 6 feet from a exit in each seperate dwelling unit of a multifamily building. This heat detector would be connected to the common area fire detection system which is connected to the public electric supply.This way when there is a real fire in any unit hopefully the heat detector will set off the buildings common fire alarm system.
Larry Fine...I haven't ever seen a 120volt hard wired smoke detector that allows more than 12 smokes to be interconnected. Sure the front of the box might say 20 detectors interconnected...but read those instructions carefully and you will see that they all limit the number of smokes to 12 maximum. This is because of the rules in NFPA 72...which is adopted by most local goverments.