How frequently do sprinklers discharge accidentally?

Accidental operation of a fire sprinkler is extraordinarily rare. Sprinkler failure due to mechanical or manufacturing failure is commonly estimated at approximately one occurrence per 16 million sprinklers per year. A sprinkler head is more than ten times less likely to fail in a given year than you are to be struck by lightning. Most unintended discharges result from physical damage, freezing, or overheating rather than a sprinkler activating on its own – and those are rare as well. The homebuilders cite NFPA's own count of non-fire activations, and that number is worth putting in context: It describes a few thousand events a year across tens of millions of sprinklers in service.