A method includes coupling a core of a heating section to a core of an overburden section of an insulated conductor. A diameter of the core of the heating section is less than a diameter of the core of the overburden section. A first insulation layer is placed over the core of the heating section such that at least part of an end portion of the core of the heating section is exposed. A second insulation layer is placed over the core of the overburden section such that the second insulation layer extends over the exposed portion of the core of the heating section. A thickness of the second insulation layer is less than a thickness of the first insulation layer and an outer diameter of the overburden section is substantially the same as an outer diameter of the heating section.