Regency's single conductor UF/TWU Irrigation Wire is manufactured for the purpose of direct burial power wire applications in accordance with Article 339 of the National Electric Code NFPA-70. Conductor construction is soft drawn bare copper meeting the requirements of ASTM Specification B-3 and B-8. Gauge sizes 18 thru 8 are solid conductors. Sizes 6 thru 4/0 are stranded conductors. The insulation is a high quality polyvinylchloride (PVC) for systems applications of up to 600 volts and conductor temperatures up to 60 C. The UF/TWU Irrigation Wire is constructed in accordance with Underwriters Laboratories, Inc. standard 493 and 83, as well as CSA 22.2 No. 75