Page 221 - Electromechanical Devices and Components Illustrated Sourcebook

Chapter 10 Wire and Conductors 183

Through Hole

Braided Cable
Panel Groove

Figure 10-45 Rubber Grommet
Molded

Rubber grommets, as shown in Figure 10-45, are the clas-
sic wire strain relief. The chassis is punched with a hole,
which matches the ID of the panel groove, and the grommet Rubber Hose
is inserted. Although it is not a generally recommended prac- Figure 10-48 Common Bend Reliefs
tice, many companies simply tie a knot in the cord to prevent
it from being pulled through.
Tab style cable clamps can be used as strain reliefs or as
internal cable supports. They are an inexpensive and effective Insulators
method to provide moderate service in this regard. Figure 10-46
shows an example of a table style cable clamp.
Electrical isolation is imperative to minimize losses and main-
tain a high degree of safety. There are a variety of insulators
on the market that are designed to accomplish just that. An
insulator is a piece of nonconductive material shaped in a
Screw
fashion that makes it convenient for electrical isolation appli-
cations.
Cable Clamp Figure 10-49 shows a basic wire and post ceramic insula-
tor. These insulators were very common in the early days of
Cable
electrification. They are still available; however, they become
less and less common as time goes on.

Flat Washer
Nut
Figure 10-46 Tab Type Cable Clamp

Romex cable clamps are very versatile devices. They are Nail
designed to clamp Romex cable in home and office wiring
systems; however, they are useful in a variety of other appli-
cations. Figure 10-47 shows a typical Romex cable clamp.
To extend the service life of a cable in heavy use, a bend
relief is applied to the cable at the clamp. Figure 10-48 shows
a few common bend reliefs. Simply adding a length of rubber Cap
hose to a cable and Romex clamp provides an excellent, low
Wire Sockets
cost solution for the problem. Many manufactured cables
come with a molded bend relief as an integral part of the
assembly. For industrial applications a braided cable bend
Base
relief is generally preferred.
Figure 10-49 Wire and Post Insulator

Clamp Screw
Body
Also used in conjunction with the wire and post insulators
Clamp Plate
are ceramic feedthrough insulators, as shown in Figure 10-50.
A hole is drilled through a joist and the insulator is pushed in.
Mount Nut
The wire is then fed through the insulator.
Insulators used on early telegraph and power poles were
Figure 10-47 Romex Cable Clamp made of soda lime glass. These insulators were clear green