ELECTRICAL
CURRENT &
CIRCUITS
ATOMIC STRUCTURE
- Electrons bounce from one atom to
another when energy or force is applied.
- This jumping of electrons is what
electricity is!!!
- How do us humans apply a force
to start the electrons movement
(electricity)???
ELECTRICITY
• Static Electricity: build up of charges that pass
QUICKLY to another object
• Electric Current: continuous flow of charges through a
conductor
Electric Currents
are
like roller coasters.
They follow a
fixed pathway.
VOLTAGE
Voltage/electricity is created by…
• a chemical cell (battery) when it changes chemical energy to
electrical energy
• by a generator when it changes mechanical energy to electrical
energy
• by a solar cell when it changes light energy to electrical energy.
Electrical
Distribution
1. Power Plant
110 kV >
2. Electricity
Travels through
the Grid
3. Substations
4. Distribution
System
33-69 kV
33 kV
Service Diagram
Service Lines
Transformer
•Step Down
12 feet off
the ground
•Step Up
•Isolation
Water Service
KWH
Meter
Ground
Branch Wires
Panel Box
The Panel Box
Purpose:
1. Distributes electricity to separate circuits
2. Prevents electrical overload which may lead
to fire
Overloads:
Too much power is drawing
from a circuit
Types of Overloads
• Simple Overload – Unplug something
• Short – Must remove and replace bad
device
Ground Fault Circuit Protection (GFCI)
What is it?
• Protects you from shock, not
overload
Where is a GFCI found?
Anywhere water and electrical items are close to
each other
•
•
•
•
•
Kitchen
Bathroom
Basement
Outside Outlets
Pool Side
Electric Circuits
• Circuits control the
movement of electric current
by providing paths for
electrons to follow.
• The path of an electric circuit
is a closed loop.
Electric Circuits
An electric circuit allows electrons to flow
from a negative pole (excess electrons) to a
positive pole (deficient in electrons)
Electric Circuits
All circuits need four basic parts: an energy source,
wires, a switch and the object that is going to change
the electrical energy into another form of energy
(load).
Energy
Source
Wire
Load
Switch
Electric Circuits
Different Types of
Circuits
Circuits are distinguished based on
the way in which loads are
connected.
Series Circuit
In a Series Circuit there is only one
path for the electric current or
electricity to flow.
Series
Circuit
• All of the loads in a
series circuit share
the same current.
• If there is any
break
in the circuit, the
charges will stop
Series Circuit
Imagine if your refrigerator and a lamp were
in a series circuit together. Your refrigerator
would run only when the lamp was on. And
when the bulb burns out, the refrigerator
would stop working.
Parallel Circuit
In a Parallel Circuit there is more
than one path for the electric current
or electricity to flow.
Parallel
Circuit
• The electric current
branches so that electrons
flow through each of the
paths
• If one path is broken,
electrons continue to flow to
the other paths
Wiring Techniques
1. Cable (Romex)
2. Conduit
– Used for protection
and routing of
electrical wiring
Types of Cables
• NMB
– Used in a house
• UF
– Used Outside and/or Underground
– Sun will not deteriorate the sheath around the wires
Ampacity
• Number of Amps the wire can handle
• 14 Gauge Wire
– Smallest Wire we can get
– Rated for 15 Amps
• 12 Gauge Wire
– Rated at 20 Amps
Smaller the gauge the larger the diameter
Reading Romex
NMB 14-2 w/g
•
•
•
•
Indoor Cable
Size 14 Gauge
2 Wires/Cables/Colors
Cable has a Ground Wire
Wire Colors and Voltages
Black
Hot
110v
Red
Hot
110v
White
Neutral
0v
Bare
Ground
0v
WHAT AFFECTS RESISTANCE?
Cable Placement
1. In a Wall
2. Along a Wall
3. Above/Along a Ceiling
18”