Basic Electricity

Basic Electrical Circuit

+ PosElectromotive Force

Neg -

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.

= Electrons

= Conductor

Resistance Load

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 DevicesLockout 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 (Voltage) = ______________ X ______________

I (Current) = ______________ X ______________

R (Resistance) = ______________ X ______________

P (Power) = ______________ X ______________

Volts

Amps

Ohms

Watts

E

RI

P

EI

Test Breaker Illustration• How many volts does a single pole breaker

supply? _______________________________• Why? _______________________________

• How many volts does a double pole breaker supply? ____________________________

• Why? ______________________________• What are two ways to test a circuit breaker?

___________and ____________• So, continuity means the breaker is _______• If a double pole breaker has 120 to ground on

each leg but when measured together reads zero is the breaker good or bad? ___________ 

It only touches one Bus Bar

120

240It Touches Two Bus Bars

Voltage Continuity

Good

Bad

Types of Wires• A wire is a _________ conductive strand• Cable contains __________strands of wire

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 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

SingleMultiple

Decreases

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.