wire which has been coated with a polymeric material is useful in a wide variety of applications . one such application is as a winding for electrical equipment such as motors , transformers , magnetic coils , relays and the like . generally , coated wires of this type have been prepared by coating the wire with multiple layers of a solution of the coating material . it has been determined that metal wires can be satisfactorily coated with a specific type of thermoplastic composition in a single layer without using solvents . this process utilizes a tubing type cross - head die with the thermoplastic composition comprising a mixture of 80 % to 99 % by weight polyethylene terephthalate and from 1 % to 20 % by weight of polyethylene , polypropylene , or a mixture thereof .