The extension cord is made of copper wire, which is a good conductor of electricity; however, it is covered with plastic, an insulator, which does not allow the electrical current to flow to you (C)
Genus represents taxonomic rank above species and below family. When organisms belong to the same genus, they must be of the same phyla, but may be in different species. In binomial nomenclature it is the generic name shared by the group of close relative.