Abstract: A fail-safe relay system for use in infrared security barriers or other apparatus producing a sensing signal so as to control the de-activation and permit the re-activation of an interconnected device; such as a machine press. The relay system uses two relays with contacts in series in conjunction with electronic circuitry. Safe-start operation for preventing reactivation of the interconnected device if any unsafe condition exists, including failure of either pair of relay contacts to open when an unsafe condition is sensed, is also accomplished.