'Oxygen free' is a necessary condition to draw copper into wire. If it's an electrically conducting copper wire it's by definition ALWAYS oxygen free.
Copper ore is crushed, floated and reduced to crude plates. These are then electrolically replated producing high purity metal. This must be further processed to get rid of the oxygen impurities left in by the plating process. After this the copper is sold as 'WIRE BAR' ie extrudable/drawable copper suitable for conductor usage. Wire bar is a quoted commodity and is the feed stock for Belden et al.
