Abstract: A low water cutoff (LWCO) device having a probe features a signal processor or processing module configured to receive signaling containing information about a difference in conductance between samples of a foam/unstable fluid line for a predetermined foam difference count that are measured on at least one test channel and sensed by the probe arranged inside a boiler, including a steam or hot water boiler or burner; and provide corresponding signaling containing information to turn OFF the boiler, based upon the signaling received.