First and foremost, whatever you install and/or connect to the FA system should be acceptable and approved by the FA manufacturer. There's a tremendous amount of liability involved with these systems and lawyers like to use the "shotgun" approach when bringing lawsuits shoud a fire occur.
Having said that, there are a couple of things you can do. A) If you only have N/O contacts available in the FA panel they should be rated for the load you are connecting. You can use an add'l SPDT relay and run the 120 volt FA relay output through the N/C side of the SPDT relay and the common out to the buzzer. To silence the buzzer use a N/O, momentary PB switch and connect it between the N/C side of the SPDT relay and the relay coil of the same relay. That way when you push the button the SPDT relay will lock-up and the buzzer will silence. When the FA is reset the relay will drop out and return to normal operation.
B) If you have SPDT contacts available in the FA panel you can use an external SPDT switch. Connect the phase leg to the common of the FA relay and connect the travelers as you would a 3-way switch. Connect the common of the switch to the buzzer. That way when the FA trips the buzzer wiill sound, moving the switch to the opposite position will silence it and when the FA is reset the buzzer will re-sound and remind you that you have to return the switch to the normal position.
Hope this helps.
Just curious, what is the buzzer for, alarm or trouble condition ?
