CHAPTER 10 Wire, Cable, and Raceway General Electrical conductor materials can be classified in three groups based on their resistivity (ohm-centimeter) properties. They include: Conductors ­ 1.59 Â 10 À6 to 400 Â 10 À6 ohm-centimeters Semiconductors ­ 10 À3 to 10 9 ohm-centimeters Dielectrics (Insulators) ­ 10 10 to <10 20 ohm-centimeters Electrical wiring is generally composed of two of those components, i.e. a conductor (#1) plus insulator (#3) in the above list.