The present invention relates to the process of extruding melt drawing fluoropolymer onto conductor to form insulated conductor at a line speed of at least 533 m/min and having no more than 10 sparks and no more than 2 lumps/13.7 km of insulated conductor under conditions that comprise an adequate process window to allow for these results to be obtained at different conditions within the process window. The invention identifies the critical parameters for achieving this process window, namely melt flow rate of the fluoropolymer, preferably being 30.+-.3 g/10 min, and the melt temperature of the extruding/melt-drawing step, preferably being 393.degree. C..+-.6.degree. C.