Abstract: High temperature insulated electrical wiring products suitable for use under service temperature classifications of at least 90.degree. C. The product comprises an electrical conductor and a polyvinyl chloride insulation covering on the conductor. The insulation comprises polyvinyl chloride resin having an inherent viscosity within the range of 1.0-1.1 and a polybasic aromatic ester plasticizing system in which the predominant ester component is a dialkyl phthalate ester. Each of the alkyl groups of the ester contains at least 11 carbon atoms. In addition, the insulation contains a higher than normal amount of antioxidant. The insulation should contain at least about 1.5 percent bisphenol A based upon the dialkyl phthalate ester. The plasticizer system may contain only dialkyl phthalate ester or it may contain minor amounts of trimellitate ester.