Hello,
Please review the current density definition at Wikipedia -
en.wikipedia.org/wiki/Current_density
Generally speaking there are standards in each country for the maximum amount of current that can be safely carried on any particular gauge size, cable design (Say the number and positioning of the conductors.) and insulation type (In your case "Heat Resisting Polyvinyl Chloride".) It holds true for the maximum applied voltage.
Electrical Utilities however usually have their own standards for HV and EHV conductors and ACSR.
Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com
519 641-3212
