We have one site that is super-safety concious and in the design for the new site fire alarm duct smoke detection was specified (by others). However,it was over egged and they installed them on the intake ducts as well as the outlets (which we pointed out!).This caused numerous false alarms and,as the system was tied into the main H & V,led to downtime because the enviroment was all off (the material made is sensitive to humidy or temperature changes). Two hours down is a lot of money lost so the intake detectors were removed.
In another part of the site the extinguishing system shuts down the computers ,originally via a standard key switch.During one maintenance someone decided to remove the key which coincided with me testing the manual releases,with the result that two computers burnt out and thet had four hours downtime (estimated production loss of £100000). After the stewards enquiry (which we got the all clear as it was their keyswitch) the switch was changed to removable key with visual indication,along with a review and modification to their lockout procedures.
Mostly,false alarms can be stopped before they occur with full consultation at the design stage to establish locations and nature of likely instances of false alarms. Getting a reputable fire company to design,install and commission a system should also help.
Our systems are installed to guarantee no false alarms (system uses algorythmns) but we have to be involved from consultation through to maintenance so we have no one to blame!