Other letters and numbers are used with these
basic letters to further identify the cable and complete
the designation. Common markings of a power sys-
tem for successive cables from a distribution switch-
board to load would be as follows: feeders, FB-411;
main, l-FB-411; submain, 1-FB-411A; branch,
1-FB-411A1; and sub-branch, l-FB-411-A1A. The
feeder number 411 in these examples shows the
system voltage. The feeder numbers for a 117- or
120-volt system range from 100 to 190; for a 220-volt
system, from 200 to 299; and for a 450-volt system,
from 400 to 499. The exact designation for each cable
is shown on the ship’s electrical wiring prints.
NEW CABLE TAG SYSTEM.—The new
system consists of three parts in sequence; source,
voltage, and service, and where practical, destination.
These parts are separated by hyphens. The following
letters are used to designate the different services:
C Interior communication
D Degaussing
G Fire control
K Control power
L Ship’s service lighting
N Navigational lighting
P Ship's service power
R Electronics
CP Casualty power
EL Emergency lighting
EP Emergency power
FL Night flight lights
MC Coolant pump power
MS Minesweeping
PP Propulsion power
SF Special frequency power
Voltages below 100 are designated by the actual
voltage; for example, 24 for a 24-volt circuit. For
voltages above 100, the number 1 shows voltages
between 100 and 199; 2, voltages between 200 and
299; 4, voltages between 400 and 499, and so on. For
a three-wire (120/240) dc system or a three-wire,
three-phase system, the number shows the higher
voltage.
The destination of cable beyond panels and
switchboards is not designated except that each circuit
alternately receives a letter, a number, a letter, and a
number progressively every time it is fused. The
destination of power cables to power-consuming
equipment is not designated except that each cable to
such equipment receives a single-letter alphabetical
designation beginning with the letter A.
Where two cables of the same power or lighting
circuit are connected in a distribution panel or
terminal box, the circuit classification is not changed.
However, the cable markings have a suffix number in
parentheses indicating the section. For example,
figure 6-1 shows that (4-168-1)-4P-A(1) identifies a
450-volt power cable supplied from a power
distribution panel on the fourth deck at frame 168
starboard. The letter A shows that this is the first cable
from the panel and the (1) shows that it is the first
section of a power main with more than one section.
The power cables between generators and
switchboards are labeled according to the generator
designation. When only one generator supplies a
switchboard, the generator will have the same number
as the switchboard plus the letter G. Thus, 1SG
identifies one ship’s service generator that supplies
the number 1 ship’s service switchboard. When more
than one ship’s service generator supplies a
switchboard, the first generator determined according
to the general rule for numbering machinery will have
the letter A immediately following the designation.
The second generator that supplies the same
switchboard will have the letter B. This procedure is
continued for all generators that supply the
switchboard, and then is repeated for succeeding
switchboards. Thus, 1SGA and 1SGB identify two
service generators that supply ship’s service
switchboard 1S.
Phase and Polarity Markings
Phase and polarity in ac and dc electrical systems
are designated by a wiring color code as shown in
6-3
