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

Objectives Identify different conductor types. Determine the cross-sectional area of a conductor. List the factors affecting resistance. Identify various insulation materials. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Objectives List three special conductor pathways. Explain the manufacture of printed circuit boards. Identify various switching devices. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Objectives Identify various lighting devices. Identify different types of resistors. Determine the value of color-coded resistors. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Conductors Copper Silver Aluminum (high-voltage lines) Brass (electrical-mechanical equipment) © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Conductors (Cont.) Transfer electrons from one atom to another within the conductor © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Computing Electrical Conductance G = 1/R G: conductance in siemens R: resistance in ohms © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Conductor Sizes Gauged by cross-sectional area Determine amount of current the conductor can handle before overheating Circular mil system © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Circular Mils (cmils) 1 mil = 0.001 inches © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Conductor Insulation Insulators Insulation on conductors as protective coating Codings © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Types of Conductors © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Conductor Resistance Cross-sectional area of a conductor Type of material Length of conductor Temperature of material © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Cross-Sectional Area of a Conductor Larger diameter has a greater current and lower resistance © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Type of Material Affects conductance and resistance © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Length of Conductor The longer the conductor is, the more resistance it has © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Temperature of Material Metals increase in resistance as ambient temperature rises Metals exposed to low temperatures become superconductors © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Safety Organizations and Standards National Fire Protection Agency (NFPA) National Electrical Code Underwriters Laboratories Inc. Occupational Safety and Health Administration Conductor voltage drop standard © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

National Fire Protection Agency NFPA dedicated to fire protection Provides information on how fires are started Provides specific prevention methods Produces National Electrical Code © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Underwriters Laboratories Inc. Independent organization that conducts tests for public safety Tests equipment for minimal safety design standards © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What are conductors? Pathways that allow current to flow through an electrical circuit © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What are four materials of which conductors are typically made? Copper, silver, aluminum, and brass © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What is the unit used to measure conductance? The siemens © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What unit is used to measure conductor sizes? Circular mils (cmils) © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What materials do not conduct electrons well? Insulators © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What is ambient temperature? Temperature of material surrounding the conductor, such as air, water, or soil © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What organization produces the National Electrical Code? National Fire Protection Agency (NFPA) © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What organization inspects equipment to award its seal of approval? Underwriters Laboratories Inc. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Special Conductor Pathways Breadboards Printed circuit boards (PCBs) Chassis © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Breadboards Provide an easy system for constructing circuits quickly Copper strips beneath the holes are conductor pathways Proto boards © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Printed Circuit Boards (PCBs) Strips of conductor material attached to an insulated board Components are soldered to conductive strips © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Chassis Older way of mounting components Part of the circuitry Not commonly used as a conductor, but still used in cars © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What is made from a thin layer of conductor material, cut into strips, and attached to an insulated board? Printed circuit board (PCB) © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Common Circuit Devices Switches Connectors Circuit protection devices © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Switches Controlled by actuators Single-pole single-throw (SPST) Single-pole double-throw (SPDT) Double-pole double-throw (DPDT) © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Switch Ratings Ampacity rating Voltage rating Exceeding ratings causes switch to fail © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Connectors Vary by type or size of conductors Solderless connectors are common © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Connectors (Cont.) Mechanical connection to larger conductors © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Circuit Protection Devices Fuses Circuit breakers © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Fuses Time required to melt fuse link is inversely proportional to amount of overload © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Circuit Breakers Resets Tripping methods Bimetallic strips Magnetism © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review How are switches controlled? By actuators © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What is the simplest type of switch? Single-pole single-throw (SPST) © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What are some common actuators? Slide, toggle, rotary, and push button © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What kind of switch has two common connection points and can provide two circuit paths simultaneously? Double-pole double-throw (DPDT) © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What are two types of switch ratings? Ampacity and voltage © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What are two common circuit protection devices? Fuses and circuit breakers © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What is another name for a circuit breaker? A reset © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Lighting Types of lighting systems Measured in lumens Incandescent lamps Discharge lamps Measured in lumens © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Incandescent Lamps Developed by Thomas Edison Tungsten filament produces light Halogen lamps © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Halogen Lamps Tungsten filaments produce light Halogen gas makes filament last longer © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Discharge Lamps Light produced by energizing gases Types: Fluorescent lamps Compact fluorescent lamps Mercury vapor lamps Neon lamps Glow lamps Strobe lamps © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Compact Fluorescent Lamps (CFLs) Special fluorescent lamps that can replace incandescent lamps Lower wattage than incandescent lamps Less heat given off than incandescent lamps © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Mercury Vapor Lamps Two electrodes in an arc tube Mercury and argon gas Heat from electrodes vaporizes mercury © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Glow Lamps Similar to neon lamps Two electrodes in a short tube Tube filled with neon or argon Lower voltages than neon lamps © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Strobe Lamps Various sizes of glass tubes Discharge of high dc voltage through tube Exciters help produce electrical arc Can generate 50,000 watts © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Lumens Lumens per watt (lpw) Light ratings Candelas Lumens © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What type of lamp is a halogen lamp? Incandescent lamp © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What category of lamps are fluorescent, neon, and mercury? Discharge lamps © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What component in a fluorescent lamp limits current through the tube? A ballast © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What kind of lamp has two electrodes in an arc tube that help vaporize the gas? Mercury lamp © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review How are different colors achieved in a neon lamp? Different gases are used © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review How are electrical arcs produced in a strobe lamp? Exciters © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Resistors Many shapes and sizes Various values of material’s wattage rating © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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 © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Potentiometers Rotary knob varies resistance Found in electronic projects Similar to wire wound resistors © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Thermistors Change resistance with temperature Prevent high current values Example: blow dryer © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Resistor Color Code Three to five color bands Bands represent different values Fourth band represents tolerance © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What is the resistor’s ability to safely dissipate heat? Wattage rating © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What are film resistors also called? Surface-mounted resistors (SMRs) © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What kind of resistors have a sliding tap? Adjustable resistors © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What type of variable resistor is similar to a wire wound resistor? A potentiometer © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What is a thermistor? A special type of resistor that can change resistance values as its temperature changes © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Review What is a tolerance? The precision to which a value can vary © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Glossary Resistor Siemens Component used to create desirable voltage drops and limit current values in electronic circuitry. Siemens Unit of measure for conductance. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

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. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Glossary Thermistor Tolerance Semiconductor device that changes resistivity with a change in temperature. Tolerance A reflection of the precision of a resistor’s value. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.

Glossary Voltage rating Wattage rating Maximum voltage for which a switch is designed. Wattage rating A resistor’s ability to safely dissipate heat. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only.