Has anyone encountered a very old fire alarm system that has a seperate 2 wire circuit with an EOL at each device? I am working on an existing fire alarm system that runs 2 wires in(red and black) and 2 wires out to next pull station or to the end of line resistor...but it also has a second circuit ( 2 blue wires) to each pull station with a different eol resistor at each pull station.

Does anyone know what the 2 blue wire circuit is and why there is a EOL at each device?




[This message has been edited by Cinner (edited 08-23-2006).]

Is it a 2 stage Fire Alarm? Are there key switches at the pull stations in addition to the regular switch?

Maybe some auxilliary control for FA initiation by Pull station like a door holder or lock?

Secure the control cabinet and bell circuits. arrange a time to pull a breakglass and see what happens.

it may be a supervisory circuit, but I am not certain...might be used to pinpoint which station is in alarm alarm

The blue wires are probably for the glass break feature. If you break the glass rod you get a trouble. I haven't seen one in a few years but used to deal with them weekly.
Dave