As an EM, you will work on electric cables.
The proper installation and maintenance of the
To do this, you must be able to recognize the
various electrical systems aboard ship are the
purpose and identify various types, sizes, capacities,
Electrician's Mate (EM) job. The repair of battle
damage, alterations, and some electrical repairs may
and uses of shipboard electrical cables. Also,
require changes or additions to the ship's cables and
you must be able to select, install, and maintain
control and protective devices. You may be required to
cables so they will be functional. To maintain an
inspect, test, and approve new installations during
electrical system in proper operating condition,
shipyard overhaul or tender availabilities.
you must know the purpose, construction, installation,
and required testing procedures for electrical
An important reference for you is the Cable
Comparison Handbook, MIL-HDBK-299 (SH). It
Upon completion of this chapter, you should be able
contains information and current data for the new
to do the following:
family of low-smoke (LS) cables authorized for
shipboard use. This handbook provides information to
1. ldentify electrical cables by classification, type
supply and installation activities on the procurement and
a n d s i z e d e s i g n a t i o n , ratings, and
use of electrical shipboard cables, particular y the
selection of suitable substitute cables for use if the
2. Recognize the different types of deck risers,
specified types and sizes aren't immediately available.
wireways, cable supports, and installations.
[t also contains information so you can select currently
available items suitable for replacement of obsolete
3. Identify the various protective devices that
include relays and circuit breakers.
4. Recognize the purpose of and identify control
For many years most of the shipboard power and
devices, to include manually and electrically
lighting cables for fixed installation had silicone-
operated contacts, limit and float switches, and
glass insulation, a polyvinyl chloride jacket, and
pilot control devices.
aluminum armor. The construction was watertight.
The determination was made that cables with all
5. Recognize the purpose for ground cables and
these features were not necessary for many
identify their requirements.
applications, especially within watertight
6. Identify various plugs and cords and their safe
compartments and noncritical areas above the
Cables jacketed with polyvinyl chloride give off
toxic fumes and dense, impenetrable smoke when
on fire. These hazards were noticed when an
electrical fire smoldered through the cable ways aboard
Shipboard electrical and electronic systems require
a large variety of electrical cables. Some circuits require
a naval ship. Because of the overwhelming amount of
only a few conductors having a high current-carrying
smoke and fumes, fire fighters were unable to
capacity. Other circuits require many conductors
effectively control the fire, which caused a lot of
having a low current-carrying capacity. Other types of
circuits may require cables with a special type of
A new family of cable was designed to replace the
insulation; for example, the conductors may have to be
silicone-glass insulation with polyvinyl chloride jacket.
shielded, or, in some cases, the conductors may have to
The new cable is constructed with a polyolefin jacket.
be of a metal other than copper.