An electric pole unit for a MV gas-insulated circuit breaker comprising: - an insulating housing defining an internal volume, in which a dielectric gas is contained; - a first pole terminal and a second pole terminal; - an interruption unit, which is positioned in the internal volume of said electric pole unit, said interruption unit comprising: - a fixed contact assembly, which is electrically coupled to said first pole terminal; - a moving contact assembly, which is adapted to be coupled with or separated from said fixed contact assembly during a switching operation of said circuit breaker, said moving contact assembly comprising a moving contact main portion, formed by an external wall of the moving contact assembly, and a moving contact arcing portion which are made of conductive material and are electrically coupled to each other, a base portion and a nozzle portion, which define a blasting chamber; - a compression cylinder defining at least partially a gas compression chamber of said interruption unit, said moving contact assembly being operatively coupled with said compression cylinder so as to move along said compression chamber during a switching operation of said circuit breaker;, wherein said compression cylinder being at least partially made of conductive material and is electrically coupled with said second pole terminal, wherein said electric pole unit comprises sliding contact means electrically coupling said moving contact assembly and said compression cylinder, characterised in that said sliding contact means comprise a conductive spring mechanically coupled with said moving contact main portion, said conductive spring being accommodated in a fixed manner in a groove obtained at the external surface of the external wall of said moving contact main portion. - an insulating housing defining an internal volume, in which a dielectric gas is contained; - a first pole terminal and a second pole terminal; - an interruption unit, which is positioned in the internal volume of said electric pole unit, said interruption unit comprising: - a fixed contact assembly, which is electrically coupled to said first pole terminal; - a moving contact assembly, which is adapted to be coupled with or separated from said fixed contact assembly during a switching operation of said circuit breaker, said moving contact assembly comprising a moving contact main portion, formed by an external wall of the moving contact assembly, and a moving contact arcing portion which are made of conductive material and are electrically coupled to each other, a base portion and a nozzle portion, which define a blasting chamber; - a compression cylinder defining at least partially a gas compression chamber of said interruption unit, said moving contact assembly being operatively coupled with said compression cylinder so as to move along said compression chamber during a switching operation of said circuit breaker;, wherein said compression cylinder being at least partially made of conductive material and is electrically coupled with said second pole terminal, wherein said electric pole unit comprises sliding contact means electrically coupling said moving contact assembly and said compression cylinder, characterised in that said sliding contact means comprise a conductive spring mechanically coupled with said moving contact main portion, said conductive spring being accommodated in a fixed manner in a groove obtained at the external surface of the external wall of said moving contact main portion. - a fixed contact assembly, which is electrically coupled to said first pole terminal; - a moving contact assembly, which is adapted to be coupled with or separated from said fixed contact assembly during a switching operation of said circuit breaker, said moving contact assembly comprising a moving contact main portion, formed by an external wall of the moving contact assembly, and a moving contact arcing portion which are made of conductive material and are electrically coupled to each other, a base portion and a nozzle portion, which define a blasting chamber; - a compression cylinder defining at least partially a gas compression chamber of said interruption unit, said moving contact assembly being operatively coupled with said compression cylinder so as to move along said compression chamber during a switching operation of said circuit breaker;, wherein said compression cylinder being at least partially made of conductive material and is electrically coupled with said second pole terminal, wherein said electric pole unit comprises sliding contact means electrically coupling said moving contact assembly and said compression cylinder, characterised in that said sliding contact means comprise a conductive spring mechanically coupled with said moving contact main portion, said conductive spring being accommodated in a fixed manner in a groove obtained at the external surface of the external wall of said moving contact main portion.