Resistors in parallel in a fire alarm initiating circuits.

Open contact with parallel resistor
Normal State 







Closed contact with 1 parallel resistor
Alarm or Supervisory Condition


Alarm state - For analog fire initiating circuits; Smoke Detectors, Heat Detectors, Water Flow, Pull Stations and similar circuits. For tamper monitory of valves the FACP should provide a Supervisory signal only.  Supervisory signals should self restore once the circuit returns to a normal state




Open contact with 1 parallel resistor with break
Trouble Condition



A line break or disconnect should cause a trouble condition which requires acknowledgement and correction before manually resetting the system.




3 open contacts with 1 parallel resistor
Normal State of a 3 device circuit



This figure shows a typical analog fire circuit containing 3 devices. These devices can be any of the devices stated in figure 2. Smokes must be 2 wire type.

Product Type