An alarm system for a smoke or fire barrier, including alarm circuits have a normally closed switch position. A control circuit connected to the alarm circuits applies a voltage to create a non-activation situation or remove a voltage to create an activation situation when the switch is open. The alarm circuit further including either a series connected resistance or a normally open switch position in parallel to the normally closed switch position, to create a “fault” condition in the absence of detection of the resistance, or an open switch position and a closed switch position.