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Basic Electricity
Basic Electrical
Circuit
+ Pos
Electromotive Force
Neg
-
Resistance Load
= Electrons
= Conductor
Voltage is applied to a circuit or load. It
is present and does not flow.
Voltage transfers along a conductor.
Current flows through a conductor.
The same amount flows throughout.
Current is not lost. Whatever leaves
the source must return to the source.
Basic Electric Safety
 Electrical Fire
• Do not use water or touch the burning object.
Why? ______________________________________
• If possible, disconnect or turn off the power. Use an
ABC Fire extinguisher and notify the Fire Department.
Call 911.
 Burns
• For a serious burn, seek immediate medical attention.
Call 911.
1st degree burn – red inflamed
2nd degree burn - Blistering
3rd degree burn - Charred
Lockout Devices
Lockout devices are commonly used on circuit breaker panels,
switches, and disconnects. They should be brightly colored and
easily visible.
The following are typical devices:
1. A circuit breaker lockout
2. A padlock
3. A lockout for an electrical cord
Types of Circuits
• Series circuit: Voltage drops but amperage stays the same.
• Parallel circuit: Amperage drops but voltage stays the same.
Illustration of Ohm’s Law
E
I
E (Voltage)
P
R
I
E
=
______________ X ______________
=
______________ X ______________
=
______________ X ______________
=
______________ X ______________
Volts
I (Current)
Amps
R (Resistance)
Ohms
P (Power)
Watts
Test Breaker Illustration
• How many volts does a single pole breaker
120
supply? _______________________________
It only touches one Bus Bar
• Why? _______________________________
• How many volts does a double pole breaker
240
supply? ____________________________
It Touches Two Bus Bars
• Why? ______________________________
• What are two ways to test a circuit breaker?
Voltage
Continuity
___________and
____________
Good
• So, continuity means the breaker is _______
• If a double pole breaker has 120 to ground on
each leg but when measured together reads
Bad
zero is the breaker good or bad? ___________
Types of Wires
Single
• A wire is a _________
conductive strand
• Cable contains __________strands
of wire
Multiple
Wire ampacity must be matched to the
specific load of its circuit.
• Why is it important to use the correct size
wire? _____________________________
• Why must aluminum wire only use devices
labeled CU/AL or CO/ALR?
• As the gauge increases the actual size of
Decreases
the wire _______________?
Wire Size
Amp Rating
Breaker Size
Voltage
#6
60
65
240
#8
40
45
240
#10
30
30
240
#12
20
20
120
#14
15
15
120
#16
Light
Extension
Cord
#18-22
T-stats
Doorbells
Types of Switches
• The purpose of a switch is to complete or break a
desired path in a circuit.
• Most switches used in residential applications are
toggle switches.
• By far the most common is the single pole switch. It
usually breaks an incoming hot wire that is connected
to one screw.
• The three-way switch has three terminals and is used
to control a circuit from two locations. One terminal is
marked COM or COMMON and that terminal is
attached to the hot wire.
• The other two terminals are switch leads.
• The double pole switch is typically used with 240 volts.
• EVERYTHING you need to know is already on the
switch!
• UL means underwriters laboratory.
• A/C means it will only handle A/C.
• CO/ALR for used with aluminum or copper.
• 15a-120v it is rated for 15 amps and 120 V.