relationship of parts. Electrical diagrams are
usually used to show how the parts of a piece of
equipment or several pieces of equipment are
wired together. These diagrams are similar to each
other. Their names are sometimes used inter-
changeably, but they do have differences.
The types of diagrams with which you will be
working are covered below. The short description
of each should enable you to recognize the dif-
ISOMETRIC WIRING DIAGRAMS
The isometric wiring diagram is not used very
often in electrical work. When used, it shows the
electrical relationship in multilevel buildings, be-
tween floors, or the total electrical system. In the
isometric diagram, the cable and fixtures are
shown only in their general location. Their exact
locations are given in the electrical prints.
(See fig. 4-4.)
Figure 4-4.Schematic wiring diagram of side-by-side
refrigerator with automatic ice maker.
Figure 4-5.Block diagram.
A block diagram is a simple drawing show-
ing the relationship of major parts of a system.
Figure 4-5 shows a block diagram of a motor con-
trol system. You can easily see why it is called a
block diagram. The parts or components in any
block diagram will be shown just as they appear
in this drawing, as blocks. They are then con-
nected by a line or lines that show the relation-
ship of the parts. The internal connections of the
components are not shown in these drawings. The
blocks are simply labeled to show what each
represents. These drawings would be of little help
The wiring diagram, which is like a picture
drawing, shows the wiring between components
and the relative position of the components.