Electrical/Electronic Drawings, Continued
Shipboard
To better understand electrical/electronic prints used on board Navy ships,
electrical prints
you should first familiarize yourself with the numbering system for electrical
units.
Numbering
All similar electrical units on a ship comprise a group. Each group has a
electrical units
separate series of consecutive numbers beginning with 1. Numbering begins
with units in the lowest foremost starboard compartment and continues with
the next compartment to port if it contains similar units; otherwise it
continues to the next aft compartment on the same level. Proceeding from
starboard to port and from forward to aft, the numbering system continues
until all similar units on the same level are numbered. It then begins again
on another level until all levels are numbered. Additional general rules for
numbering electrical units are as follow:
Within a given compartment, lower takes precedence over upper, forward
over aft, and starboard over port.
Electrical distribution panels, control panels, and so forth, are given
identification numbers made up of three numbers separated by hyphens.
The first number identifies the vertical level by deck or platform number
at which the panel is normally accessible. The second number identifies
the longitudinal location of the unit by frame number. The third number
identifies the transverse location by the assignment of consecutive odd
numbers for centerline and starboard locations and consecutive even
numbers for port locations.
Main switchboards or switch gear groups supplied directly from ship’s
service generators are designated with the suffix S. For example 1S, 2S,
and so forth.
Switchboards supplied directly by emergency generators are designated
1E, 2E and so on.
Switchboards for special frequencies (other than the frequency of the
ship’s service system) have alternating current (ac) generators designated
1SF, 2SF, and so on.
Continued on next page
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