Fully insulated tip unit for a lightning protection system for a wind turbine blade and a wind turbine blade comprising the same

A fully insulated tip unit (1) for a lightning protection system for a wind turbine blade (2) is disclosed, comprising an electrically conducting tip (3), which tip consists of an external part (4) and an internal part (5), at least one side receptor base (6), an internal tip unit conductor (8), an insulated electric cable (9) for forming the outermost part of a down conductor (10), and a connection element (12) for establishing electrical connection between the insulated electric cable and the other conducting parts of the tip unit, wherein the internal part of the tip, the side receptor base(s), the internal tip conductor, the connection element and one end of the insulated electric cable are all embedded by casting in an insulating material (13) leaving only the external part of the tip and the other end of the insulated electric cable uncovered by the insulating material. Furthermore, a wind turbine blade comprising such a tip unit is disclosed.