Do you have 120 VAC Daisy Chain Smokes Alarms in your Home or Apartment Unit ? is your Home or Building Built Before 2004 ? THEY MAY NOT WORK - Better ? why is UL and NFPA still approving there use

It was all the rage back in the 80's when 120 Volt  AC  Powered Daisy Chain  Smoke Alarms came out then then with a 9 volt DC battery back up  in case you lost power  in your new home.
Considered the finest in new home fire safety technology every new home had them installed on every level .

http://www.handymanhowto.com/how-to-install-a-hardwired-smoke-alarm-part-2/

NFPA codes even allowed them to be used in small apartment buildings  and town homes under 6 units  a very big  and deadly mistake .

Because  there is one major problem If you have a home with 120 VAC smokes built before 2004
will the smokes even go into alarm?

This is because it has been found that smoke alarms which utilize Ionization technology can fail to operate after 10 years 

http://www.safelincs.co.uk/why-should-smoke-alarms-be-replaced-after-ten-years/

Personally I have never liked Ionization detector and alarms of any type I have always tried to install Photoelectric smokes which when properly maintained can last for decades.

But because Ionization units are cheaper thats what builders installed  by the millions  and many home and apartment owners have no idea the 120 VAC Daisy Chain units they installed over 10 years ago may no longer work ,because they mistakenly believe it only applies to stand alone 9 Volt Dc smokes not daisy chains.

The bigger problem to is it often takes the additional cost of an electrician to replace them because they utilize 120VAC 

There are hundreds of thousands of home owners who think they are being protected when they are not.  It still amazes me how many homes and  places I walk in and no smoke alarms period.

But to add to this deadly problem is all the small apartment houses and town homes where these 120 VAC units where used  that never get checked or inspected  . Because these small buildings do not have a fire alarm system .

It was seen as a burden to make small apartment buildings put in a fire system yet these typically have more fires than large buildings and are often built of much more flammable construction than a regular brick apartment building.

But as usual NFPA and UL has been short sighted in there thinking and have exposed millions of people to fire hazards because they allowed a less stringent code for small apartment buildings.

and have made it worse by not emphasizing that 120 VAC smoke alarms need changed after 10 years also.