NT I put the same argument to CT and his response was,
Tam, if challenged in court is that what they will say. I have no idea what malfunctioned your honour but I know it malfunctioned. A false alarm is no a system malfunction, Tam, it is more commonly the case that the system functioned entirely correctly or as the technology was bound to perform , so there is nothing for the fire alarm engineer to work out.
Tam, the point is that very commonly it is not known if there was human intervention or an environmental cause or electromagnetic interference or steam that has long ago dispersed or someone having a cigarette illicitly, or an electrical storm in the area. Malfunctions of equipment causing false alarms are rare and often impossible to prove (unless you have been to lots of fires in England, and then you will be a world authority). But all these other causes such as human stupidity or lack of control of premises which is the cause of most false alarms cannot be charged for, so it is all so much hot air really.
and I think he has a strong point.