SWITCHES, PROTECTIVE DEVICES, AND CABLES
Upon completion of this chapter, you will be able to do the following:
Describe the characteristics, construction features, applications, and mainte-
nance procedures of the various types of switches, relays, and solenoids.
Identify the characteristics, functions, and maintenance procedures of the
various types of protective devices on IC equipment.
Identify electrical cables by classification, type and size designation, ratings,
Describe the proper procedures for installing and connecting cables.
Identify the purpose and the installation and maintenance procedures of
radio-frequency coaxial cable.
maximum allowable voltage and current of the circuit
in which the switch is to be used. Since it is placed in
As an Interior Communications (IC) Electrician,
series, all the circuit current will pass through the
you will be working with sophisticated circuitry
switch; because it opens the circuit, the applied
consisting of complex equipment, multiconductor
voltage will appear across the switch in the open
cables and connectors, and a variety of switching and
circuit position. Switch contacts should be opened and
protective devices. This chapter will give you a basic
closed quickly to minimize arcing; therefore, switches
understanding of the hardware that is in general use
normally use a snap action.
with interior communications systems. You will be
able to recognize installations and, with limited
TYPES OF SWITCHES
supervision, you will be able to install this hardware
aboard ship. It should be understood that, due to the
There are many types and classifications of
vast numbers of components used, not every
switches. A common designation is by the number of
component is discussed, but rather the common
poles, throws, and positions. The number of poles
installations. For more detailed information
indicates the number of terminals at which current can
concerning the operation and theory of circuit
enter the switch. The throw of a switch signifies the
switching and protective devices, consult NEETS,
number of circuits each blade or contactor can
Module 3, NAVEDTRA 172-03-00-85.
complete through the switch. The number of positions
indicates the number of places at which the operating
device (toggle, plunger, and so on) will come to rest.
Another means of classifying switches is the
A basic understanding of switches and their uses
method of actuation; that is, knife, toggle, push button,
is a necessity for the IC Electrician. The Navy uses
or rotary. Further classification includes a description
hundreds of different types of switches.
of switch action, such as on-off, momentary on-off,
A switch is a device used for making, breaking, or
and on-momentary off. Momentary contact switches
changing connections in an electrical circuit. Switches
hold a circuit closed or open only as long as the
are rated in amperes and volts; the rating refers to the
operator deflects the actuating control.