An electrical appliance including at least one sheet-shaped electrode and a connecting device for electrically connecting the at least one electrode to a voltage source. The connecting device includes a casing having two or more tubular casing parts. Each casing part enclosing a channel filled with a dielectric medium, and an elongated conductor for feeding electric power from the voltage source to the at least one electrode. The conductor extends through the channels of the casing parts and is surrounded by the dielectric medium therein. The conductor extends through a hole in an electrically conductive member of each individual electrode. The conductor is electrically connected to the conductive members of the electrodes and each individual electrode has a part arranged between two of the casing parts with the two casing parts clamped against opposite sides of the intermediate electrode part.