The present invention relates to a downhole line separation tool for submerging into a casing in a wellbore, the downhole line separation tool having a first tool end, a second tool end and a tool axis, comprising a tool housing having a first housing part and a second housing part, an electrical motor arranged within the first housing part and powered through a wireline connected to the first tool end, an annular separation element having an element end facing away from the first tool end and being rotatably connected within the second housing part, and a rotatable shaft arranged within the second housing part and rotated by the electrical motor for rotating the annular separation element, wherein the second housing part comprises a sleeve part having a sleeve end, at least part of the annular separation element projecting from the sleeve end further away from the first tool end than the sleeve, the second housing part comprising at least one projecting part extending further away from the first tool end than the annular separation element along the tool axis. Moreover, the present invention also relates to a downhole system comprising an upper casing connected to a lower casing and arranged in the wellbore.