a volatile casing for the second shell during production application_number US 53023908 A description the section shown in the figure passes through a longitudinal axis 1 with respect to which a disconnecting switch device 2 is essentially rotationally symmetrical by way of example the disconnecting switch device 2 is used for surge arresters surge arresters are used for voltage dependent connection and disconnection of a current path which runs from a conductor which is live during operation to a ground potential switching is carried out for example by means of varistors in the surge arresters varistors are semiconductor elements which can fail for example when electrically overloaded when a surge arrester fails an undesirable ground fault can be formed in order to cope with a situation such as this a disconnecting switch device is additionally inserted in the current path the disconnecting switch device 2 shown in the figure has a first electrode piece 3 and a second electrode piece 4 the two electrode pieces 3 4 are rotationally symmetrical and are arranged opposite one another coaxially with respect to the longitudinal axis 1 an annular electrically insulating spacer 5 is arranged on the mutually opposite sides of the electrode pieces 3 4 and the electrode pieces 3 4 rest on this spacer 5 the spacer 5 surrounds an arc gap which is formed between the two electrode pieces 3 4 the first electrode piece 3 has a projecting plateau 6 in order to guide.