If a fire alarm goes off how does it alert the fire department?

Answer 1

Dial-up link to the fire department, or to a central office that monitors burglar alarm, and then they contact the fire department.

Now, if the alarm has been turned "off" then that's a different matter.

Some systems, like mine, have the ability to monitor the fire / smoke sensors even though the burglar system isn't activated.
Excessive cooking smoke or a closed damper in the fireplace can still trigger an alarm condition and set things in motion. They call the house to verify the situation. If I answer and give the password I can cancel the alarm. If no answer, they call the fire department.

If yours is a system that literally is either "on" or "off" for all functions, and you leave it "off" and a fire breaks out, then your only hope is that someone sees it and notifies the fire department.

Answer 2

The alarm is hooked up to a phone line (ONLY if you are signed-up with an alarm company for monitoring. Otherwise, your alarm only sounds. It does not send a signal.)

The alarm dials out to an alarm company's "monitoring center". The monitoring station receives the signal through the phone line, it is interpreted by a "receiver" (which decodes which account the alarm is coming from, which type of alarm and which "zone" is alarming) and sent to a queue on a dispatcher's screen. The dispatcher calls the fire department and alerts them to the fire. The whole process usually takes less than a minute! The same is true for burglar alarms, panic alarms, etc.

I used to work at an "alarm center" as a dispatch operator.

Answer 3

Not all fire alarms alert the fire dept. In a fire situation, a call should also always be made to 911 from a safe location.

When they do alert the fire dept., it usually takes place by calling out on a phone line and reporting to a monitoring service, just as livysmom27 described very accurately.

Answer 4

unless you have a security system, those little circlular alarms you buy aren't connected to the fire department. You or your neighbor have to call in the fire.

Answer 5

Telephone