The vast majority of cables connected to electricity around your home will contain some copper. 

High grade cable

This cable is typically min. 40% copper. Without sampling the cable there is no way to know for sure, however if you cut the cable and look at the cross section and see a big and thick single solid strand of copper inside, or three thick solid strands with very little plastic it is unlikely to be low grade cable. 

Low grade cables

These are cables with a low copper content or cables that are “pluggy” meaning they still have plugs or adapters attached to them. 

Low copper content can be identified by either sampling the cable or rough estimate by looking at the cross section when you cut the cable in half. If you see lots of very thin strands of copper surrounded by a lot of plastic or steel, it is low grade cable.