a switchgear has an interrupter unit that includes an arc gap . a first and a second switching contact piece are movable relative to one another . a switching - gas duct originates in the arc gap and connects the arc gap to the surroundings of the interrupter unit . a hollow vessel arrangement delimits at least some sections of the switching - gas duct and is connected to one of the contact pieces . the hollow vessel arrangement includes an external outlet opening for the switching - gas duct .