Daily Lesson

1
Daily Lesson

• Electrical Conductors
• Prepared by
• Brian Alexander
• This lesson is from Virginia Tech and has not
  been edited by the Georgia Curriculum Office.

2
Electrical Conductors

• Performance Objectives
• Student will be able to (SWBAT)
• 1. Describe the basic types of electrical
  conductors.
• 2. Explain how electrical conductors are
  classified.
• 3. Explain the purpose of wire insulation.
• 4. Describe electrical cables.

3
Electrical Conductors

• Enabling Objectives
• SWBAT
• 1. Identify the different types of conductors.
• 2. Describe the pros and cons of different
  electrical conductors.
• 3. Explain how electrical conductors are sized.

4
Electrical Conductors

• Enabling Objectives (Continued)
• 4. Describe color coding used in electrical
  wiring.
• 5. Describe the types of insulators used to
  cover electrical conductors.
• 6. Identify the types of electrical cable used
  in Agriculture and residential applications.

5
Electrical Conductor

• Critical Thinking
• What is an Electrical Conductor?
• Anything that transmits electricity.

6
Warning

• Interest Approach
• Electricity is always looking for a conductor!

7
Common Electrical Conductors

• Silver-- Best
• Copper -- 2nd
• Gold-- 3rd
• Aluminum-- 4th
• Tungsten-- Poor

8
Silver

• Precious metal
• High cost
• Not practical for wire
• Corrosive problems (such as silver tarnishes)

The Silver Nugget which was reputedly the largest
silver nugget ever mined came out in three pieces
from the Smuggler or the Molly Gibson
minesironically after silver prices had crashed
in 1893.
9
Copper

• Used in many wiring applications
• Reasonable cost
• Flexible
• Easy to make into wire
• Good corrosion resistance

10
Gold

• Precious Metal
• Very expensive
• Does not corrode
• Seldom used as a wire
• Used to plate (coat) connectors in electronic
  devices

11
Aluminum

• Abundant metal
• Reasonable cost
• Flexible
• Light weight
• Corrosion problems / reacts with other metals

12
Aluminum (continued)

• Used in large wire sizes - power lines and
  service entrance cable
• Electrical wire 4 and larger is usually
  aluminum and stranded.
• Pound for pound aluminum is a better conductor
  than copper.

13
Tungsten

• Rare metal
• Used to make light-bulb filaments
• High melting point
• Poor conductor
• Electrodes for TIG Welding

14
Electrical Wire Size

• the larger the wire, the more electricity it can
  carry
• wire size is expressed by numbers from the
  American Wire Gauge system (AWG)
• the larger the wire size, the smaller the AWG
  number

15
Wire Size Chart
16
Wire Sizing

• Sizing conductors according to load
• Need to know the desired voltage drop
• Need to know the load in amps on the circuit
• Need to know the length of circuit in feet
• Need to know the Voltage of the circuit
• Use the wire sizing tables to determine what size
  conductor to use.

17
Wire Identification (examples)

• 12/3 G or 12-3 w/G
• 12 is the gauge of the conductor wire
• 3 is the number of conductors
• G or w/G means there is a safety ground wire also

18
Color Code for Wires

• Individual wires are color coded to identify
  their function.

19
Wire Color Code Chart
20
Wire Insulation

• Prevents electricity from jumping from one
  conductor to another (prevents short circuits)
• Most wires are insulated with plastic vinyl
• Individual wires have color coded insulation

21
Types of Insulation

• R Rubber Insulation
• RH Heat Resistant Rubber
• RW Moisture Resistant Rubber
• Ru Latex Rubber
• RuA Latex Rubber with Asbestos
• sub.

22
Electrical Cables

• A group of two or more wires enclosed in a metal,
  rubber, or plastic sheath is called a cable.
• The sheath protects the wire from damage.
• Metal conduit also protects wires, but is not
  considered a cable.

23
Common Types of Cables
24
Electrical Conductors

• Summary
• Many materials have the ability to conduct
  electricity.
• Wire size is important for proper and safe
  electrical conduction.
• The color code on wires is used to identify the
  wires purpose.

25
Electrical Conductors

• The insulation on a wire prevents electricity
  from jumping from one conductor to another.
• Electrical cables are use extensively in
  agricultural, industrial, business and
  residential applications.