Q. When one sprinkler activates, do they all activate?
A. No.
Each sprinkler head works independently from the others and is activated by a heat only sensitive mechanism. Only the sprinkler over the fire will activate. Should the fire continue to spread, then and only then will another sprinkler activate. In most home fires, only one or two sprinklers are actually triggered. Burnt toast or smoke will not activate a sprinkler, only heat in excess of approximately 68°C/155°F.
 
Q. Can the sprinklers go off by accident?
A. The odds are 1 in 16 million.
According to the factory Mutual Research Corporation the odds of a sprinkler going off accidentally are 1 in 16 million. You have better odds of getting struck by lightning or winning the lottery than having a sprinkler activate accidentally. All new sprinkler systems use sprinklers and piping that are rated for normal system pressures to 175 psi. These components can withstand pressure far in excess of that for short periods of time. All systems are pressure tested at 200 psi for two (2) hours as is required by the manufacturer's and local fire codes.
 
Q. Will there be excessive water damage from the sprinklers going off in the event of a fire?
A. Consider this
A residential fire sprinkler puts out roughly 15 gallons of water per minute while a fire hose sprays about 150 gallons of water per minute. In comparison, water damage would be far less than the alternatives.
 
Q. Would my water damage insurance go up?
A. No.
In fact you should receive a discount for having a residential fire sprinkler system. If you do not receive a discount that you feel is adequate, then shop around.