ANSWER TO REVIEW QUESTION 7
The power system is generally considered to be a combination of two sections - the transmission system
and the distribution system. (para 3-16)
ANSWER TO REVIEW QUESTION 8
Using table 3-4, a bare stranded copper wire with a resistance of .12617 ohm per 1,000 feet at 20 degrees C
and a current capacity of 186 amps is an AWG size #1. (para 3-18) (table 3-4)
Section V. Electrical Wiring
a. Conductors. A conductor is any wire bar,
3-20. DEFINITION
or ribbon, with or without insulation. It is usually
The electrical wiring system in a building is the
made of copper because of the good electrical
installation which distributes electrical energy. It is
characteristics of that metal. The smallest size wire
frequently referred to as the "interior wiring system"
permitted for use in interior wiring systems is 14
to distinguish it from the "electric distribution
AWG. The determination of the wire size to be used
system" which includes outside power lines and
in circuits is dependent on the voltage drop
equipment for multibuilding installations.
coincident with each size. The size of the conductor
used as feeder to each circuit is also based on voltage
drop. You would select the wire size so that the
3-21. NOMENCLATURE
voltage drop from the branch circuit supply to the
The nomenclature of a building wiring system is
outlets will not be more than 3 percent. Table 3-9,
divided into two principal parts according to function
which is based on an allowable 3-percent voltage
as follows:
drop, lists the wire sizes required for various
distances between supply and load, at different load
a. Building Feeders and Subfeeders. A
currents. Table 3-9 also lists the service-wire
building feeder is a set of conductors supplying
requirements and capacities. The minimum size for
electricity to the building. A subfeeder is an
service-wire installation shall not be smaller than the
extension of the feeder through a cutout, or switch,
conductors of a branch circuit and in no case smaller
from one interior distribution center to anther without
than No. 12. Service-wires must not only meet the
branch circuits between.
voltage-drop requirements but also be inherently
strong enough to support their own weight, plus any
b. Branch or Branch Circuits. A branch
additional loading caused by nature (ice, branches,
circuit is a set of conductors, feeding through an
etc.). Symbols are used on electrical plans to show
automatic cutout, or fuse, and supplying one or more
the routing and interconnection of wiring. The
energy-consuming devices such as lights or motors.
symbols that you will most frequently encounter are
shown in figure 3-31. Wiring may be divided into
four classes according to type of installation or the
materials used.
3-22. MATERIALS AND FITTINGS
A variety of materials and fittings are used in the
(1) Expedient wiring. There are many
installation of electrical wiring. Some common items
applications where electrical wiring installations are
you use in theater of operations type construction are
needed for temporary use. One example is a forward
described in the following paragraphs.
area installation. A complete installation including
knobs, tubes, cleats, and damage protection would
require
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