This standard applies to the materials@ constructions@ and testing of single conductor cables and assemblies of completed single conductor thermoset insulated cables@ with an insulated or bare copper or an insulated aluminum neutral@ used for the distribution of electrical energy at phase-to-phase voltages not exceeding 600 volts@ or phase-to-ground voltage not exceeding 480 volts@ 60 Hz@ and at conductor temperatures not exceeding 90 ??f or use in direct burial and underground ducts.