A switch is disclosed, in particular a switch disconnector for low voltages, including at least one cuboid pole housing; a switching shaft which runs transversely with respect to the side walls and disconnects contact elements which are resting on one another in order to open the switch; and an aperture opening formed in one wall of the pole housing. In order to prevent the risk of an electrical flashover to the rear wall, it is proposed in at least one embodiment, that the aperture opening is formed in a side wall, to which a channel is connected, which dissipates any overpressure that occurs in the pole housing in an end-face outlet direction.