Would EVAC systems not be grandfathered in because they can be easily programmed with the the 520hz square tone? I don’t know, and am hoping someone with experience could tell me. All of this is out of curiosity.
they’re always grandfathered.
the sound file and amp have to be ul listed with the speakers to produce a proper 520hz tone, which is a harmonic pattern, not just a simple frequency. so it’s not as straight forward as it sounds since hardware would likely need to be replaced. 520hz devices also use more power, so existing circuits and equipment may not be able to handle the extra load. not to mention someone would have to pay a fire alarm company to come out and change it the programming, and the frequency response of a lot of older speakers weren’t designed to deal with 520hz, so field devices may need to be replaced…
you’re simply not going to run into 520hz in many places for years to come. no existing systems in existing buildings will ever be forced to upgrade to them, and most new construction right now don’t fall under the latest codes that require 520hz so very few new systems being installed as we speak have the requirement.
the most i’ve done is 520hz audible bases on military bases which are about the only ones who are quick to adopt the latest codes. i work in some cities still using nfpa 101 -2000 edition, and a LOT of cities have stuck with nfpa 72-2007 to avoid a lot of the mass notification requirements.
most evac systems are also in places where the occupants aren’t sleeping, so 520hz isn’t needed to wake anyone up.