Electrical/Electronic Drawings, Continued
Zone control
numbers
Larger ships are numbered according to a zone control system. This system
generally coincides with the fire zones prescribed by the ship’s damage
control plan. Load center switchboards distribute electrical power within
each zone. Load center switchboards and miscellaneous switchboards on
ships with zone control distribution are given identification numbers.
The
first number represents the zone, and the second number represents the
switchboard within the zone.
Cable markings
Cable labels are metal tags embossed with identification numbers attached to
cable wire as close as practical to each point of connection on both sides of
decks, bulkheads, and barriers. There are two systems for marking electrical
cables on ships. The old system of cable markings appear on ships built
before 1949. The tags are red (vital), yellow (semivital), and grey (nonvital).
Letter designators identify power and lighting cables for different services.
The new cable tag system appears on ships built after 1949. The new system
consists of three parts in sequence: source, voltage, and service. When
practical, destination may also appear on the tag.
Figure 4-23 is an example of a marked cable tag.
Figure 4-23.—A cable tag.
Continued on next page
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