A quenching chamber in medium-voltage switch disconnectors includes a body made of a gassing material that is of a solid shape similar to a rectangular prism. The chamber includes an arcing knife channel and an arc chamber hollowed in the body and is fitted with an arcing contact unit located in a socket. The arc chamber extends directly along the arcing knife channel from a back wall of the chamber and is connected with the inside of the arcing knife channel through a gap that forms a flat funnel. The height of the funnel decreases with an increase in the distance to the arcing knife channel. The width of the gap is less than the width of the arcing knife channel measured in a plane perpendicular to the side walls of the body.