In the last few weeks I’ve learned more about leak sensors then i care to know. We have been dealing with nagging sensors that have different things going on with them. So what i know about sensors is they talk about “PNP” type and “NPN” type this sounds a lot like transistor logic. This logic could be referring to the profiling in typical fashion that a transistor would be drawn electrically. Also from what i was told the sensor would be profiled to be a short and close on sensing moisture. Or the digital would be a zero and go to one upon sensing. The other type sensors are the “NPN”, these sensors work opposite of the way the PNP sensors work. They are closed and alarm open if sensing moisture, or are high and go low on the sense, or another way to say it, are signaling one and go to zero with water… more on this subject later when i understand more about them.