load, high or low voltage, or short-circuit conditions
that the entire installation is not shown in figure 3-34.
and is sometimes substituted for the entrance switch
The diagram shows the splices, support, and insulator
in small building electrical installations. No fuses are
arrangements used. Note that this is a physical
used in the circuit breaker. The breaker is generally
drawing rather than symbolic one, so each line
operated automatically although manual operation is
represents a single wire rather than a pair of
provided for. As a rule, no detailed wiring diagram
conductors as in the plan. A note calls out a circuit
for a circuit breaker is shown on construction prints
breaker installation detail at the point where the wires
since such diagrams are to be found on the outside of
are down to the circuit-breaker panel, and the
the circuit breaker box cover.
arrowheads on the leader from the note show the
direction from which the circuit breaker installation
detail is drawn. The circuit breaker panel installation
detail (figure 3-35) shows the installation
3-23. ELECTRICAL PLANS
arrangement for the circuit breakers, including
a. Electrical plans show what items are to be
grounding, splices, and connections to the incoming
installed, their approximate location, and the circuits
service. Note that the circuit breaker panels are
to which they are to be connected. A typical
placed 5 feet, 6 inches from the floor line. You can
electrical plan for a post exchange is shown in figure
also see that a 3/4-inch pipe driven 8 feet into the
3-33. The plan shows that the incoming service
ground is used for grounding the No. 8 ground wire.
consists of three No. 8 wires and that two circuit-
breaker panels are to be installed. Starting at the
b. In some installations alternate outlets are
upper left, the plan shows that nine ceiling lighting
connected to different circuits so that half the lighting
outlets and two duplex wall outlets are to be installed
may be turned on at one time and only part of the
in the bulk storage area. The arrow designated "B2"
service will be out if a circuit breaker is tripped. For
indicates that these outlets are to be connected to
these plans, the circuit identification (Al, B1, etc.) is
circuit 2 of circuit-breaker panel B. Note that three
noted alongside each fixture.
wires are indicated from this point to the double
home-run arrows designated "B1, B2." These are the
c. Wiring plans are not usually provided for
hot wire from the bulk storage area to circuit 2 of
the fixtures themselves. If the connections are not
panel B, the hot wire from the administration area to
obvious, diagrams are normally supplied with the
circuit 1 of panel B, and a common neutral. From the
device. A three-way switch circuit, which enables
double arrowhead, these wires are run to the circuit
the control of a single outlet from two locations, is
breaker panel without additional connections. This
shown in figure 3-36. On an electrical plan you will
run is shown at the left side of figure 3-34, which is
find the three-way switch is indicated by the symbol
typical of the ceiling wiring diagrams provided for
S3.
open wiring of medium or extreme complexity. Note
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