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Electrical Conductors
A.
Bhatia
Overview
A conductor is a
piece of metal used to conduct electricity, known colloquially as an electrical
wire. Wires are
very good conductors, which mean that they have very little resistance. In fact,
their resistance is so small that often we consider it to be zero. (In other
words, we often treat wires as perfect conductors).
In the United
States, conductors are measured by American wire gauge
(abbreviated
AWG)
for smaller ones,
and circular mils for larger ones.
To give you some idea how
thick these wires are; AWG 0000 wire is about 11.7 millimeters in diameter (a
little less than one-half inch thick) and at the opposite end of the scale, AWG
40 is less than 0.1 millimeters in diameter (about as thick as a strand of hair
from your head). The wiring inside the walls of your home is usually AWG 10 or
AWG 12 wire.
Of the metals
commonly used for conductors, copper, has a high conductivity. Silver is more
conductive, but due to cost it is not practical in most cases. Compared to
copper, aluminum has worse conductivity per unit volume, but better
conductivity per unit weight. In many cases, weight is more important
than volume making aluminium the 'best' conductor material for certain
applications. For example, it is commonly used for large-scale power
distribution conductors such as overhead power lines.
Conductors are
usually surrounded by and/or supported by insulators and the insulation
determines the maximum voltage that can be applied to any given conductor. The
ampacity of a conductor, that is, the amount of current it can carry, is related
to its electrical resistance; a lower-resistance conductor can carry more
current. The resistance, in turn, is determined by the material of the conductor
and its size. For a given material, conductors with a larger cross-sectional
area have less resistance than conductors with a smaller cross-sectional area.
This 3-hr
course provides general requirements, classifications and application
information for electrical conductors. The course is
based entirely on Naval
Education and Training Materials (NAVEDTRA
14176), Electricity and
Electronic Training Series;
Module-4 and covers Chapter 1 titled
“Electrical Conductors”.
The student must take a multiple-choice quiz consisting of
fifteen (15) questions at the end of
this course to obtain PDH credits.
Specific Knowledge or Skill Attained
This course teaches the following specific knowledge and
skills:
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The
definitions of unit size, mil-foot, square mil, and circular mil.
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Specific resistance, including the three factors used to
calculate it in ohms.
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The
proper use of the American Wire Gauge when making wire measurements.
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The factors required in selecting proper size wire.
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The advantages and disadvantages of copper or aluminum as
conductors.
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Insulation resistance and dielectric strength.
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The safety precautions to be taken when working with insulating
materials.
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The most common insulators used for extremely high voltages.
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The design and use of coaxial cable
Course
Click on the following PDF attachment and review the document prior to taking
a quiz for credit.
Electrical Conductors (396 KB)
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credit. Click on the link below.
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