Electrical Installation-I
Module 3:
Electrical Installation Drawings
PREPARED BY
IAT Curriculum Unit
Jan 2010
© Institute of Applied Technology, 2010
ATE312 – Electrical Installation-I
Module 3:
Electrical Installation Drawings
Module Objectives
Upon successful completion of this module, students will be able to:
•
state the purpose of electrical installation drawings.
•
differentiate
between
circuit/schematic diagrams
•
identify the symbols and terminology used in installation and
schematic diagrams.
•
implement electrical installation drawings.
installation/wiring
diagrams
and
Module Contents:
Topic
Page No.
3.1
Introduction
3
3.2
Electrical Installation Drawing Types
4
3.2.1 Installation/Wiring Diagram Symbols
5
3.2.2 Terminology
6
3.3
Schematic Diagram
8
3.4
Electrical Installation Drawing Examples
10
3.5
Lab Activity 1
11
3.6
Lab Activity 2
12
3.7
Lab Activity 3
13
3.8
Module Exercise
14
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Module 3: Electrical Installation Drawings
ATE312–Electrical Installation-I
3.1 Introduction
In the field of electrical installation, the ability to read and understand
schematics and drawings is an absolute must. Electrical installation
drawings provide an electrician with the technical information needed to
install the wiring system in apartments or buildings. Figure 3.1 below is
a typical electrical installation in an apartment which has a DB, two
switches, two sockets and bulb.
Figure 3.1: Wiring in buildings
Several
types
of
electrical
drawings
technicians. This module explains
are
used
by
engineers
and
two different types of installation
drawings which are as follows:
1. Installation or Wiring Diagrams
2. Schematic or Circuit Diagrams
The differences between these drawings will be emphasized and the
purpose of each type will be clarified.
Module 3: Electrical Installation Drawings
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ATE312 – Electrical Installation-I
3.2 Electrical Installation Drawing Types
The Installation diagram or Wiring diagram is a detailed diagram that
shows the electrical or electronic components, connectors, connecting
wires. It also identifies the wires by wire numbers or color coding.
Figure 3.2 shows a typical example of an installation drawing used in the
construction industry. The drawing shows the wiring in different rooms,
number of wires, type of load such as switches, lamps, sockets etc.
Figure 3.2: Installation diagram in the architectural plan
The wiring diagram in the architectural plan shown in figure 3.2 however,
does not show the functional details of the electrical installation. Details
such as the interconnection of various components like switches, junction
boxes, light fittings etc. will not be shown. An electrician requires the
above details in order to link and connect the components and connecting
lines of an installation. These details are shown on the Schematic
diagram or Circuit diagram of an electrical installation explained under
section 3.3.
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Module 3: Electrical Installation Drawings
ATE312–Electrical Installation-I
3.2.1 Installation/Wiring Diagram Symbols
The Wiring Diagram uses a number of symbols to indicate the wiring
system components. The commonly used symbols are given below:
Symbol Name
Symbol
Connection line
Protective earth line
Signal line
Distribution device
Number of wires in the
cable
(n:number of wires)
Or
(a cable with 3 wires)
Junction box
Lamp
One gang one way switch
Module 3: Electrical Installation Drawings
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ATE312 – Electrical Installation-I
Symbol Name
Symbol
Socket outlet, single
phase
Pushbutton
Two gang one way switch
One gang two way switch
Intermediate switch
3.3.2 Terminology:
1. One gang one way switch: One light operated by one switch
2. One gang two way switch: One light operated by two switches
3. Two gang one way switch: Two one way switches in a single module
4. Intermediate switch: Switch of 4 terminals used to control devices
from more than two locations.
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Module 3: Electrical Installation Drawings
ATE312–Electrical Installation-I
Skill 1
Identify the different component symbols, draw them, and write their
symbol names in the table given below:
Symbol
Symbol Name
Module 3: Electrical Installation Drawings
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ATE312 – Electrical Installation-I
3.3 Schematic Diagram
Schematic diagrams show the electrical systems, and are used for
understanding the electrical functions of a wiring system. The schematic
is a representation of how the circuit works. Regardless of how the
components are physically laid out, the schematic shows the logical order
of how they are used together.
Symbol Name
Schematic Diagram
Symbol
Connection line
Protective earth line
Signal line
Line to indicate
component housing
Fixed connection
Movable connection
Terminal connection
strip
Junction box
Earth connection
Electric fuse
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Module 3: Electrical Installation Drawings
ATE312–Electrical Installation-I
Electric lamp
MCB
Socket outlet, single
phase
Pushbutton
One gang one way switch
Two gang one way switch
One gang two way switch
Intermediate switch
One gang one way two
pole switch
Module 3: Electrical Installation Drawings
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ATE312 – Electrical Installation-I
3.4
Electrical Installation Drawing Examples:
The following examples demonstrate the comparisons between a Wiring
diagram and a Schematic diagram:
Example 1: Installation drawing of a simple room
Wiring diagram: The wiring Schematic diagram: In this schematic
diagram shows that one lamp in diagram, each individual connection line
this room is operated by one is shown and more detailed graphical
switch.
symbols
are
used
to
indicate
the
electrical details of the wiring.
Example 2: Installation drawing of a room with two doors.
Wiring diagram: In this case, the Schematic
diagram:
The
room has two doors for entry, and schematic diagram for the circuit is
therefore the ceiling lamp is as shown.
operated by two switches.
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Module 3: Electrical Installation Drawings
ATE312–Electrical Installation-I
3.5 Lab Activity 1
Objective: Draw the installation/wiring diagram for the represented
physical arrangement of safety plug sockets for a workbench. Indicate the
number of wires, and use proper symbols.
Module 3: Electrical Installation Drawings
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ATE312 – Electrical Installation-I
3.6 Lab Activity 2
Objective:
Draw
the
Schematic
diagram
for
the
following
arrangement.The protective conductor is to be connected with the lamp
housing
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Module 3: Electrical Installation Drawings
ATE312–Electrical Installation-I
3.7 Lab Activity 3
Objective:
Draw the Schematic diagram for the following TWO-WAY
switching circuit.
Module 3: Electrical Installation Drawings
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ATE312 – Electrical Installation-I
3.6 Module Exercise
1. Compare between schematic diagrams and wiring diagrams:
Schematic diagram
Wiring diagram
2.Draw the Installation/Wiring diagram for the following schematic:
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Module 3: Electrical Installation Drawings
ATE312–Electrical Installation-I
Notes
Module 3: Electrical Installation Drawings
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ATE312 – Electrical Installation-I
Notes
16
Module 3: Electrical Installation Drawings