A base plate and/or a sensor assembly part for an ostomy appliance and related method is disclosed, the base plate and/or the sensor assembly part comprising: a first adhesive layer with a proximal side configured for attachment of the base plate and/or the sensor assembly part to the skin surface of a user, the first adhesive layer having a stomal opening with a center point; and a plurality of electrodes including a first leakage electrode, a second leakage electrode, and a third leakage electrode, wherein the plurality of electrodes is configured to detect presence of fluid on the proximal side of the first adhesive layer in a primary sensing zone and a secondary sensing zone, the primary sensing zone arranged in a primary angle space from the center point of the first adhesive layer and the secondary sensing zone arranged in a secondary angle space from the center point of the first adhesive layer.