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ELECTRICAL CONDUCTORS
LEARNING OBJECTIVES Learning objectives are stated at the beginning of each chapter. These learning objectives serve as a preview of the information you are expected to learn in the chapter. The comprehensive check questions are based on the objectives. By successfully completing the OCCECC, you indicate that you have met the objectives and have learned the information. The learning objectives are listed below. Upon completing this chapter, you should be able to:
ELECTRICAL CONDUCTORS In the previous modules of this training series, you have learned about various circuit components. These components provide the majority of the operating characteristics of any electrical circuit. They are useless, however, if they are not connected together. Conductors are the means used to tie these components together. Many factors determine the type of electrical conductor used to connect components. Some of these factors are the physical size of the conductor, its composition, and its electrical characteristics. Other factors that can determine the choice of a conductor are the weight, the cost, and the environment where the conductor will be used. CONDUCTOR SIZES To compare the resistance and size of one conductor with that of another, we need to establish a standard or unit size. A convenient unit of measurement of the diameter of a conductor is the mil (0.001, or onethousandth of an inch). A convenient unit of conductor length is the foot. The standard unit of size in most cases is the MILFOOT. A wire will have a unit size if it has a diameter of 1 mil and a length of 1 foot. SQUARE MIL The square mil is a unit of measurement used to determine the crosssectional area of a square or rectangular conductor (views A and B of figure 11). A square mil is defined as the area of a square, the sides of which are each 1 mil. To obtain the crosssectional area of a square conductor, multiply the dimension of any side of the square by itself. For example, assume that you have a square conductor with a side dimension of 3 mils. Multiply 3 mils by itself (3 mils X 3 mils). This gives you a crosssectional area of 9 square mils. Figure 11.  Crosssectional areas of conductors. Q.1 State the reason for the establishment of a "unit size" for conductors. To determine the crosssectional area of a rectangular conductor, multiply the length times the width of the end face of the conductor (side is expressed in mils). For example, assume that one side of the rectangular crosssectional area is 6 mils and the other side is 3 mils. Multiply 6 mils X 3 mils, which equals 18 square mils. Here is another example. Assume that a conductor is 3/8 inch thick and 4 inches wide. The 3/8 inch can be expressed in decimal form as 0.375 inch. Since 1 mil equals 0.001 inch, the thickness of the conductor will be 0.001 X 0.375, or 375 mils. Since the width is 4 inches and there are 1,000 mils per inch, the width will be 4 X 1,000, or 4,000 mils. To determine the crosssectional area, multiply the length by the width; or 375 mils X 4,000 mils. The area will be 1,500,000 square mils. Q.4 Define a square mil as it relates to a square conductor. 
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