the invention relates to a disconnecting switch assembly for disconnecting air - insulated electrical lines , which have one or more phases , with at least one grounded housing that is filled with protective gas , with open air ducts , which are attached to the housing in a gastight manner and which each have an open - air connection for connecting the lines , and with gas - insulated disconnecting switches , which are placed inside the open - air ducts . at least three open air ducts are provided for each phase whose open - air connections can be electrically connected to one another by means of the disconnecting switch over current path piece mounted inside the housing .