Abstract: Stresses are relieved in elongated extruded plastic members by passing electric currents through electrical conductors embedded in the reinforcing bars. The reinforcing bars are manufactured according to a pultrusion process in which 1/16 inch diameter MIG wire is introduced into a roving bundle of impregnated fibers and drawn through a curing and shaping die. The resulting product is a rigid reinforcing bar having a longitudinal wire extending its entire length. The reinforcing bars are cut to lengths corresponding to the desired lengths of the elongated members to be extruded. The elongated member is manufactured using an extrusion process in which molten plastic surrounds a plurality of reinforcing bars to form a continuously extruded member. The member is cooled, cut at the reinforcing bar joints, and prepared for electrical resistance heating. Electrical contacts are inserted into bores provided in the ends of each reinforcing bar and are placed in electrical contact with the embedded wire.