NB-138 Water Leak Detector is an electronic device designed to detect the presence of water in places that need to be protected in order to give timely warning against water leaks. In general, it is a device that gives warning after contact of two contact terminals with water according to the principle of electrical conductivity of water, lying flat on the ground and connected to a small cable. The device then gives an audible alarm, providing a forward signal when there is enough water to bridge the contacts. They are placed near any potentially water-leaking area, such as HVAC, water pipes, drainpipes, water tanks, living quarters, and summer houses.