An electrical insulating device for a linear component forming part of a fuel system subjected to risks of possible external electrical discharges formed by a part (13) made of insulating material attached to two metal flanges (15, 17) that allow inserting the device (11) between two parts of said linear component, said part (13) being formed by a cylindrical body (21) with a castellated crown (23) on its outer side, formed by longitudinal (25) and transverse (27) segments, and said metal flanges (15, 17) having transverse projections (31, 33) facing the transverse segments (27) of the castellated crown (23) for facilitating their attachment by suitable means (39).