Electrical Estimating Methods, 4th Edition

CHAPTER 13 Conductors and Grounding

A conductor is a wire or metal bar with a low resistance to the flow of electric current. Grounding is accomplished by a conductor connected between electrical equipment or a circuit and the earth. In this chapter, there are 11 sections on various types of wiring and terminations, and a section on grounding. Each section begins with a definition of the component, followed by units of measure, material and labor requirements, and a takeoff procedure.

WIRE

Wire is used to conduct current from an electrical source to an electrical use. Wire is made of either copper or aluminum conductors with an insulating jacket. Copper is normally used for sizes smaller than #6, while copper or aluminum is used on #6 and larger. Wire comes with various voltage ratings and insulation materials. Some types of insulation are thicker than others and require a larger-size conduit. Aluminum conductors of equal ampacity, or ampere capacity, are generally larger in diameter than copper and may require larger diameter conduit.

The cost impact of using different types of wire goes beyond the cost of the wire itself. Labor productivities, and ultimately the cost for pulling various sizes and types of wire must also be considered. Another factor is that because of the composition of the wire (copper versus aluminum), the same size (gauge) wire will have different capacity ratings. Consider the following: #6 copper wire is rated at 65A, and #6 aluminum is rated at 50A. ...