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 OCC-ECC, 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:
1. Recall the definitions of unit size, mil-foot, square mil, and circular mil and the mathematical
equations and calculations for each.
2. Define specific resistance and recall the three factors used to calculate it in ohms.
3. Describe the proper use of the American Wire Gauge when making wire measurements.
4. Recall the factors required in selecting proper size wire.
5. State the advantages and disadvantages of copper or aluminum as conductors.
6. Define insulation resistance and dielectric strength including how the dielectric strength of an
insulator is determined.
7. Identify the safety precautions to be taken when working with insulating materials.
8. Recall the most common insulators used for extremely high voltages.
9. State the type of conductor protection normally used for shipboard wiring.
10. Recall the design and use of coaxial cable.
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
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.
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 one-thousandth of an inch). A convenient unit of conductor length is the foot. The standard unit of size
in most cases is the MIL-FOOT. A wire will have a unit size if it has a diameter of 1 mil and a length of 1