Chapter 9 Electrical Wiring Diagram Basics 203
Copyright Goodheart-Willcox Co., Inc.
9.2.1 Pictorial Wiring Diagrams
A pictorial wiring diagram is an illustration of a circuit that shows
the location of electrical components and all electrical connections.
A technician uses this diagram to see each wire connection between
devices. Pictorial diagrams can contain renderings that resemble the
components in the actual circuit. See Figure 9-3. These diagrams often
include details, such as the device ratings, wire gage, wire colors, num-
ber of phases, voltage rating, and amperage rating.
Pictorial diagrams look similar to schematic diagrams, but show more
exact physical locations of the components in the device. See Figure 9-4.
Goodheart-Willcox Publisher
Figure 9-3. A traditional pictorial wiring diagram.
115 V, 15 A,
one-phase
75-watt
(typical)
14-gage
(stranded)
BLK
WHT
Motorized vent damper
To transformer
primary
Thermostat Limit switch
Legend
Factory line voltage Y -Yellow BK -Black
Factory low voltage P -Purple BL -Blue
Field low voltage W -White O -Orange
BR -Brown G -Green
Notes
1. Optional safety switches such as a roll out, stack switch, or fusble link.
BL BL
BL
BLOBK
BK W
BK R BK P
BK BK
Y
Y Y
Gas valve
W
W
W W
BR
BR R
R
1
Circulator pump
G
Neutral
Hot
120 VAC
R C
W G
R W
Coil Coil
4
1
6
3
Jason Obrzut
Figure 9-4. Another version of a pictorial wiring diagram.