This depends on the type of sensor being deployed. For example, capacitive level sensors react to conductive materials and non-conductive materials with a dielectrically constant Epsilon >1. The switching point depends on the material. When the sensor-tip is immersed in a fluid, a switching command inside the device is triggered. This trigger is set between contact with the liquid and some mm more into the liquid. This distance between the tip of the sensor and the trigger is the nominal switching point. The immersion-distance has a negative sign, e. g. -8 mm. The water content of an object or a liquid has a decisive influence on the switching point. A high humidity content increases the switching point considerably. If the sensor is moistened with conductive materials, its function can be impaired when a conductive film builds up, that electrically connects the sensor electrode with a metallic conducting side. For an ultrasonic sensor the switching point is the distance from the sensor face at which the output is switched on or off.