Automatic sprinklers are highly effective elements of total system designs for fire protection in
buildings. When sprinklers cover the area of fire origin, they operate in 95% of all reported structure fires large enough to activate sprinklers. When they operate, they are effective 96% of the time, resulting in a combined performance of operating effectively in 91% of reported fires where sprinklers were present in the fire area and fire was large enough to activate sprinklers. When wet-pipe sprinklers are present in structures that are not under construction and excluding cases of failure or ineffectiveness because of a lack of sprinklers in the fire area, the fire death rate per 1,000 reported structure fires is lower by 80% for home fires, where most structure fire deaths occur, and the rate of property damage per reported structure fire is lower by 45-70% for most property uses. Also, when sprinklers are present in structures that are not under construction and excluding cases of failure or ineffectiveness because of a lack of sprinklers in the fire area, 94% of reported structure fires have flame damage confined to the room of origin compared to 74% when no automatic extinguishing equipment is present. When sprinklers fail to operate, the reason most often given (63% of failures) is shutoff of the system before fire began. (All statistics are based on 2003-2006 fires reported to U.S. fire departments, excluding buildings under construction.)