Abstract: An electrical fire protection system including a plurality of extinguishant filled suppressor units activatable by explosive squibs connected in series. In response to the detection of an abnormal condition associated with fires, a control circuit initiates an activating current flow that detonates the explosive squibs and induces release of the extinguishant from the suppressor units. A supervisory current supply establishes through the series connected squibs, a constant level of supervisory current flow that is insufficient to induce detonation of the squibs but establishes a detectable voltage drop thereacross. In response to the detection of an abnormally high voltage level across the series connected squibs, a switching circuit switches the squibs from a series to a parallel circuit relationship.

Abstract: A fire protection system including a plurality of suppressor units activatable to suppress a detected fire; a plurality of electrical current responsive activators, one associated with each of the suppressor units and adapted to induce activation thereof; a control circuit connecting the activators in series and including an actuator for initiating activating current flow to the activators; and an auxiliary circuit for connecting the activators parallel in response to the initiation of activating current flow by the actuator, the auxiliary circuit including a plurality of electronic switches, one connected between the supply and each of the junctions between each pair of series connected activators.