A base plate of an ostomy appliance includes a first adhesive layer and a masking element. The first adhesive layer includes a stomal opening with a center point and a proximal surface configured to be attached to a skin surface of a user. The masking element is arranged on a distal surface of the first adhesive layer and is more insulative than the first adhesive layer. A plurality of electrodes is arranged on the distal surface of the first adhesive layer, where each electrode includes a sensing part and a conductor part. The masking element is arranged between the conductor part of each electrode and the first adhesive layer. The electrodes are formed on a proximal surface of a support layer.