2. Introduction to Basic Electrical Circuit Materials
Chapter 3
Introduction to Basic Electrical Circuit Materials

3. Objectives Identify different conductor types.
Determine the cross-sectional area of a conductor.
List the factors affecting resistance.
Identify various insulation materials.
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4. Objectives List three special conductor pathways.
Explain the manufacture of printed circuit boards.
Identify various switching devices.
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5. Objectives Identify various lighting devices.
Identify different types of resistors.
Determine the value of color-coded resistors.
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6. Conductors Copper Silver Aluminum (high-voltage lines)
Brass (electrical-mechanical equipment)
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7. Conductors (Cont.)
Transfer electrons from one atom to another within the conductor
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8. Computing Electrical Conductance
G = 1/R
G: conductance in siemens
R: resistance in ohms
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9. Lesson in Safety Your body can conduct electricity
Electric current can flow into one hand, through your body, and out your other hand
Can be fatal
Keep one hand in a pocket to avoid shock
Stand on insulated materials when working with high voltage
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10. Conductor Sizes Gauged by cross-sectional area
Determine amount of current the conductor can handle before overheating
Circular mil system
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11. Circular Mils (cmils) 1 mil = 0.001 inches
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12. Conductor Insulation Insulators
Insulation on conductors as protective coating
Codings
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13. Insulation Codings Code letters Color coding R rubber H heat
HH high heat
A asbestos
T thermoplastic
M oil resistant
UF underground feeder
C corrosion resistant
Color coding
Used to trace the insulation through a building
Can represent certain voltages, polarities, or grounding conductors
Governed by building codes or manufacturing associations
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14. Types of Conductors © Goodheart-Willcox Co., Inc.
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15. Conductor Resistance Cross-sectional area of a conductor
Type of material
Length of conductor
Temperature of material
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16. Cross-Sectional Area of a Conductor
Larger diameter has a greater current and lower resistance
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17. Type of Material Affects conductance and resistance
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18. Length of Conductor
The longer the conductor is, the more resistance it has
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19. Temperature of Material
Metals increase in resistance as ambient temperature rises
Metals exposed to low temperatures become superconductors
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20. Safety Organizations and Standards
National Fire Protection Agency (NFPA)
National Electrical Code
Underwriters Laboratories Inc.
Occupational Safety and Health Administration
Conductor voltage drop standard
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21. National Fire Protection Agency
NFPA dedicated to fire protection
Provides information on how fires are started
Provides specific prevention methods
Produces National Electrical Code
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22. National Electrical Code
Regulations to ensure safety
Standards apply to design of electrical systems
Adopted by government agencies at city, county, state, and federal levels
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23. Underwriters Laboratories Inc.
Independent organization that conducts tests for public safety
Tests equipment for minimal safety design standards
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24. Occupational Safety and Health Administration
Part of U.S. Department of Labor
Responsible for worker safety
Conducts on-site inspections
Authority to inspect and fine industries that do not meet safety standards
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25. Conductor Voltage Drop
NEC’s maximum voltage drop standard for branch circuits
A 3% voltage drop is the maximum permissible
CMA: area in cmils
K: material constant
I: amperage
L: length of wire
VD: voltage drop
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26. Review What are conductors?
Pathways that allow current to flow through an electrical circuit
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27. Review What are four materials of which conductors are typically made?
Copper, silver, aluminum, and brass
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28. Review What is the unit used to measure conductance? The siemens
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29. Review What unit is used to measure conductor sizes?
Circular mils (cmils)
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30. Review What materials do not conduct electrons well? Insulators
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31. Review What is ambient temperature?
Temperature of material surrounding the conductor, such as air, water, or soil
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32. Review What organization produces the National Electrical Code?
National Fire Protection Agency (NFPA)
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33. Review
What organization inspects equipment to award its seal of approval?
Underwriters Laboratories Inc.
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34. Special Conductor Pathways
Breadboards
Printed circuit boards (PCBs)
Chassis
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35. Breadboards Provide an easy system for constructing circuits quickly
Copper strips beneath the holes are conductor pathways
Proto boards
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36. Printed Circuit Boards (PCBs)
Strips of conductor material attached to an insulated board
Components are soldered to conductive strips
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37. Construction of PCBs Copper foil used as conductor material
Resist material put on copper foil for circuit design
Etchant removes all of copper but circuit design
Photographic process uses light exposure and solvent to make circuit design
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38. Chassis Older way of mounting components Part of the circuitry
Not commonly used as a conductor, but still used in cars
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39. Review What is a breadboard?
A pathway that consists of a series of holes aligned in rows across the entire surface of an insulation material
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40. Review
What is made from a thin layer of conductor material, cut into strips, and attached to an insulated board?
Printed circuit board (PCB)
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41. Common Circuit Devices
Switches
Connectors
Circuit protection devices
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42. Switches Controlled by actuators Single-pole single-throw (SPST)
Single-pole double-throw (SPDT)
Double-pole double-throw (DPDT)
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43. Switch Ratings Ampacity rating Voltage rating
Exceeding ratings causes switch to fail
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44. Connectors Vary by type or size of conductors
Solderless connectors are common
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45. Connectors (Cont.) Mechanical connection to larger conductors
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46. Circuit Protection Devices
Fuses
Circuit breakers
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47. Fuses
Time required to melt fuse link is inversely proportional to amount of overload
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48. Circuit Breakers Resets Tripping methods Bimetallic strips Magnetism
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49. Review How are switches controlled? By actuators
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50. Review What is the simplest type of switch?
Single-pole single-throw (SPST)
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51. Review What are some common actuators?
Slide, toggle, rotary, and push button
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52. Review
What kind of switch has two common connection points and can provide two circuit paths simultaneously?
Double-pole double-throw (DPDT)
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53. Review What are two types of switch ratings? Ampacity and voltage
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54. Review What are two common circuit protection devices?
Fuses and circuit breakers
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55. Review What is another name for a circuit breaker? A reset
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56. Lighting Types of lighting systems Measured in lumens
Incandescent lamps
Discharge lamps
Measured in lumens
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57. Incandescent Lamps Developed by Thomas Edison
Tungsten filament produces light
Halogen lamps
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58. Halogen Lamps Tungsten filaments produce light
Halogen gas makes filament last longer
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59. Discharge Lamps Light produced by energizing gases Types:
Fluorescent lamps
Compact fluorescent lamps
Mercury vapor lamps
Neon lamps
Glow lamps
Strobe lamps
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60. Fluorescent Lamps Filament or electrode Air removed from tube
Tube filled with inert gas and mercury
Mercury vaporized by heat
Ballast in tube limits current
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61. Compact Fluorescent Lamps (CFLs)
Special fluorescent lamps that can replace incandescent lamps
Lower wattage than incandescent lamps
Less heat given off than incandescent lamps
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62. Mercury Vapor Lamps Two electrodes in an arc tube
Mercury and argon gas
Heat from electrodes vaporizes mercury
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63. Neon Lamps Two electrodes in a long glass tube
Shaped for various applications
Tube filled with neon gas
High voltage to create current
Other gases can be used for different colors
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64. Glow Lamps Similar to neon lamps Two electrodes in a short tube
Tube filled with neon or argon
Lower voltages than neon lamps
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65. Strobe Lamps Various sizes of glass tubes
Discharge of high dc voltage through tube
Exciters help produce electrical arc
Can generate 50,000 watts
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66. Lumens Lumens per watt (lpw) Light ratings Candelas Lumens
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67. Review What type of lamp is a halogen lamp? Incandescent lamp
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68. Review What category of lamps are fluorescent, neon, and mercury?
Discharge lamps
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69. Review
What component in a fluorescent lamp limits current through the tube?
A ballast
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70. Review
What kind of lamp has two electrodes in an arc tube that help vaporize the gas?
Mercury lamp
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71. Review How are different colors achieved in a neon lamp?
Different gases are used
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72. Review How are electrical arcs produced in a strobe lamp? Exciters
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73. Resistors Many shapes and sizes
Various values of material’s wattage rating
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74. Types of Resistors Molded composition resistors
Film resistors, or surface-mounted resistors (SMRs)
Wire wound resistors
Adjustable resistors
A sliding tap allows the resistance to be varied
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75. Potentiometers Rotary knob varies resistance
Found in electronic projects
Similar to wire wound resistors
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76. Thermistors Change resistance with temperature
Prevent high current values
Example: blow dryer
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77. Resistor Color Code Three to five color bands
Bands represent different values
Fourth band represents tolerance
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78. Review What is the resistor’s ability to safely dissipate heat?
Wattage rating
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79. Review What are film resistors also called?
Surface-mounted resistors (SMRs)
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80. Review What kind of resistors have a sliding tap? Adjustable resistors
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81. Review
What type of variable resistor is similar to a wire wound resistor?
A potentiometer
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82. Review What is a thermistor?
A special type of resistor that can change resistance values as its temperature changes
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83. Review What is a tolerance? The precision to which a value can vary
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84. For Discussion
What items other than an automobile could use a chassis as a conductor?
Discuss why a good understanding of the relationship among conductors, insulators, and semiconductors is important.
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85. Glossary Actuator Adjustable resistor
A mechanical device that causes a circuit to open and close.
Adjustable resistor
A type of wire-wound resistor in which one side of the wire is exposed.
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86. Glossary Ambient temperature Ampacity rating
The temperature of the material (air, water, or soil) surrounding the conductor.
Ampacity rating
An indication of how much current a switch can safely handle.
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87. Glossary Ballast Branch circuit
Fine wire used to limit the current inside the phosphor tube of a fluorescent lamp.
Branch circuit
The wiring from an electrical circuit panel to the last device connected in that circuit.
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88. Glossary Breadboard Candela
An easily constructed circuit board used for experiments or prototypes. Also called a protoboard.
Candela
A brightness rating based upon the amount of light generated by one candle.
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89. Glossary Chassis Circuit breaker
A metallic surface upon which electronic components are mounted.
Circuit breaker
Safety device that automatically opens a circuit if it is overloaded.
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90. Glossary Circular mil (cmil) Conductor
Cross-sectional area of a conductor one mil in diameter.
Conductor
A low-resistance material through which electric current can easily flow.
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91. Glossary Discharge lamp Fuse
Produces light by energizing a gas such as argon, neon, helium, or a vapor of mercury or sodium.
Fuse
Safety device that opens an electric circuit if it becomes overheated.
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92. Glossary Incandescent lamp Insulation
Light and heat are created from current flowing through a filament.
Insulation
A protective coating that keeps the electron flow contained to the conductor path.
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93. Glossary Insulator Lumen
A material that possesses a high resistance to current flow (electricity).
Lumen
A measure of the amount of light generated by a lighting system.
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94. Glossary Lumens per watt (lpw) Mil Potentiometer
The amount of light produced for each watt of energy used.
Mil
One thousandth of an inch (0.001").
Potentiometer
Type of variable resistor that uses a rotary knob to vary the resistance value.
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95. Glossary Printed circuit board (PCB) Reset
Made from very thin layers of conductive material (such as copper) adhered to a plastic backing. The circuit is etched to leave active pathways for the circuitry.
Reset
A device used to protect a circuit from overload and short circuit conditions. Also called a circuit breaker.
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96. Glossary Resistor Siemens
Component used to create desirable voltage drops and limit current values in electronic circuitry.
Siemens
Unit of measure for conductance.
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97. Glossary Single-pole Single-throw
Refers to a switch that provides one path for electron flow. The switch can be turned on or off.
Single-throw
Refers to a switch that controls only one circuit.
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98. Glossary Sliding tap Superconductor
An instrument that moves across the exposed surface of a portion of the wire in an adjustable resistor, allowing the resistance value to be varied.
Superconductor
A conductive material that is exposed to extremely low temperatures, causing its resistance value to approach zero.
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99. Glossary Thermistor Tolerance
Semiconductor device that changes resistivity with a change in temperature.
Tolerance
A reflection of the precision of a resistor’s value.
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100. Glossary Voltage rating Wattage rating
Maximum voltage for which a switch is designed.
Wattage rating
A resistor’s ability to safely dissipate heat.
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