Print Reading for HVACR, 1st Edition Page 202 (220 of 368)

202 Print Reading for HVACR
Copyright Goodheart-Willcox Co., Inc.
Abbreviations
CAP Capacitor
CB Circuit breaker
CC Compressor contactor
CC1, CC2 Contactor contacts 1, 2
CCH Crankcase heater
CFM Condenser fan motor
COMP Compressor
CR Cooling relay
CT Control transformer
DFT Defrost timer
DIM Draft inducer motor
EDH Electric duct heater
F Fuse
FLK Fusible link
FLO Flow switch
FLS Fan limit switch
FLT Float switch
GND Ground
GV Gas valve
HPS High pressure switch
HR Heating relay
HSI Hot surface igniter
IFM Indoor fan motor
IFR Indoor fan relay
L1, L2 Line 1, line 2
LIM Limit switch
LPS Low pressure switch
NC Normally closed
NO Normally open
ODT Outdoor thermostat
OL Overload
RC Run capacitor
ROS Roll-out switch
RV Reversing valve (coil)
SC Start capacitor
SAIL Sail switch
SEQ Sequencer
SS Spill switch
T-STAT Thermostat
T1, T2 Terminal 1, terminal 2
TM Timer motor
X-FRM Transformer
Goodheart-Willcox Publisher
Figure 9-2. Common abbreviations found on electrical wiring diagrams.
Switches Single-pole single-throw (SPST)
Single-pole double-throw (SPDT)
Double-pole single-throw (DPST)
Double-pole double-throw (DPDT)
Limit switch (normally open)
Limit switch (normally closed)
Float switch (open on level rise)
Float switch (closed on level rise)
Flow switch
Manual switch (normally open)
Manual switch (normally closed)
Sail switch
High-pressure switch
Low-pressure switch
Heating thermostat
Cooling thermostat
Transformers Control transformer
Overloads Overload
Goodheart-Willcox Publisher Figure 9-1. (continued )

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202 Print Reading for HVACR
Copyright Goodheart-Willcox Co., Inc.
Abbreviations
CAP Capacitor
CB Circuit breaker
CC Compressor contactor
CC1, CC2 Contactor contacts 1, 2
CCH Crankcase heater
CFM Condenser fan motor
COMP Compressor
CR Cooling relay
CT Control transformer
DFT Defrost timer
DIM Draft inducer motor
EDH Electric duct heater
F Fuse
FLK Fusible link
FLO Flow switch
FLS Fan limit switch
FLT Float switch
GND Ground
GV Gas valve
HPS High pressure switch
HR Heating relay
HSI Hot surface igniter
IFM Indoor fan motor
IFR Indoor fan relay
L1, L2 Line 1, line 2
LIM Limit switch
LPS Low pressure switch
NC Normally closed
NO Normally open
ODT Outdoor thermostat
OL Overload
RC Run capacitor
ROS Roll-out switch
RV Reversing valve (coil)
SC Start capacitor
SAIL Sail switch
SEQ Sequencer
SS Spill switch
T-STAT Thermostat
T1, T2 Terminal 1, terminal 2
TM Timer motor
X-FRM Transformer
Goodheart-Willcox Publisher
Figure 9-2. Common abbreviations found on electrical wiring diagrams.
Switches Single-pole single-throw (SPST)
Single-pole double-throw (SPDT)
Double-pole single-throw (DPST)
Double-pole double-throw (DPDT)
Limit switch (normally open)
Limit switch (normally closed)
Float switch (open on level rise)
Float switch (closed on level rise)
Flow switch
Manual switch (normally open)
Manual switch (normally closed)
Sail switch
High-pressure switch
Low-pressure switch
Heating thermostat
Cooling thermostat
Transformers Control transformer
Overloads Overload
Goodheart-Willcox Publisher Figure 9-1. (continued )

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Chapter 9 Electrical Wiring Diagram Basics 201
Copyright Goodheart-Willcox Co., Inc.
an electrical circuit. Sets of contacts are identifi ed as normally open (NO)
or normally closed (NC). Normally open (NO) indicates contacts that are
open in their de-energized state. Normally closed (NC) indicates contacts
that are closed in their de-energized state.
A relay is an electrical switch that is controlled by an external electri-
cal signal. Its electrical contacts are operated by electromagnets. When
an external electrical signal is applied, the relay’s coil becomes energized
and a magnetic fi eld is generated. This magnetic fi eld moves an armature
to change the contact’s positions. Relay contacts are either NO or NC.
A solenoid is an electromagnetic device that converts electric current to
mechanical movement by producing a magnetic fi eld. This device is com-
monly installed into a valve body and used to control the direction of fl ow
of refrigerant, gas, or water by opening, closing, or repositioning the valve.
9.2 Electrical Symbols and Wiring Diagrams
Many symbols used in wiring diagrams represent specifi c electrical com-
ponents and devices in a circuit. These symbols may vary based on who
creates the prints, but they typically follow a standard convention. A
separate reference document is sometimes used in completed diagrams
that identifi es the symbols employed in the diagram. Common electrical
symbols are shown in Figure 9-1. A list of abbreviations is often provided
with many electrical wiring diagrams and is shown in Figure 9-2.
An electrical wiring diagram is a representation of an electrical cir-
cuit and shows how electrical loads, switches, and other devices are con-
nected in an appliance or system. These diagrams provide information
that can be used by both installers and service personnel to install and
troubleshoot electrical systems. There are three common types of electri-
cal wiring diagrams: pictorial diagrams, schematic diagrams, and ladder
diagrams. Each is used for a specifi c purpose. Depending on the type of
wiring diagram being used, the information it contains may vary.
Goodheart-Willcox Publisher
Figure 9-1. Commonly used electrical symbols in wiring.
(continued on next page)
Electrical Symbols
Device Type Symbol
Contacts Normally open
Normally closed
Timed-controlled
Relays Relay coil
Motor starter
MS
Sensors Light-dependent resistor
Thermistor
Electric sensor

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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.

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