Electrical Principles and Electrical Principles and Wiring MaterialsWiring Materials

OBJECTIVESOBJECTIVES1.1. AM16.01 Define common electrical terms. AM16.01 Define common electrical terms. 2. AM16.02 Compute electrical energy use and 2. AM16.02 Compute electrical energy use and

cost. cost. 3. AM16.03 Investigate safe practices involving 3. AM16.03 Investigate safe practices involving

electricity. .electricity. .4. AM17.01 Describe materials used in electric 4. AM17.01 Describe materials used in electric

wiring. wiring. 5. AM17.02 Explain the procedure for installing 5. AM17.02 Explain the procedure for installing

switches, making common splices, and switches, making common splices, and doing other electrical wiring tasks.doing other electrical wiring tasks.

I. Principles of ElectricityI. Principles of Electricity

A. A. ElectricityElectricity is a form of energy that can is a form of energy that can produce produce lightlight, , heatheat, , magnetismmagnetism, , chemical changeschemical changes

B. B. ResistanceResistance: tendency of a material to : tendency of a material to preventprevent electrical flow electrical flow

C. C. ConductorConductor: if electricity : if electricity flows easilyflows easily

D. D. InsulatorInsulator: material that provides : material that provides great great resistanceresistance

II. TERMSII. TERMS

A. A. AmperesAmperes: measure of the : measure of the rate of flowrate of flow of of electricity in a conductor electricity in a conductor (gallons/min)(gallons/min)

B. B. VoltsVolts: measure of electrical : measure of electrical pressure pressure (PSI)(PSI)

C. C. WattsWatts: measure of the : measure of the amount of energy or amount of energy or workwork that can be done that can be done

D. D. OhmsOhms: measure of : measure of electrical resistanceelectrical resistance to flowto flow

III. Ohm’s LawIII. Ohm’s Law

A. Ohm = R (resistance)A. Ohm = R (resistance)

B. Volts = E (pressure)B. Volts = E (pressure)

C. Amps = I (rate of flow)C. Amps = I (rate of flow)

D. Ohm’s Law: D. Ohm’s Law: E = IR or I=E/R or R=E/IE = IR or I=E/R or R=E/I

IV. Electrical SafetyIV. Electrical SafetyA. Two most dangerous things about Electricity- A. Two most dangerous things about Electricity-

Shock and FireShock and Fire

B. B. Never disconnectNever disconnect any safety device any safety device

C. C. Don’t touch electricalDon’t touch electrical items with items with wetwet hands or hands or feet (sweat)feet (sweat)

D. Don’t remove ground plug prongD. Don’t remove ground plug prong

E. Use GFI in wet areas-E. Use GFI in wet areas-GGround round FFault ault IInterrupternterrupter

F. Discontinue use of extension cord that feels warmF. Discontinue use of extension cord that feels warm

G. Don’t put extension cords under carpetG. Don’t put extension cords under carpet

V. Electrical SafetyV. Electrical SafetyA. Install wiring according to NEC- A. Install wiring according to NEC- NNational ational

EElectrical lectrical CCodeodeB. Blown fuse or breaker, determine causeB. Blown fuse or breaker, determine causeC. Don’t replace fuse with larger fuseC. Don’t replace fuse with larger fuseD. Don’t leave heat producing appliances D. Don’t leave heat producing appliances

unattendedunattendedE. Heaters & lamps away from combustiblesE. Heaters & lamps away from combustiblesF. Don’t remove back of TV (30,000v when off)F. Don’t remove back of TV (30,000v when off)G. Electric motors lubricated, free of grease G. Electric motors lubricated, free of grease

etc.etc.

Electrical SafetyElectrical Safety

H. Keep appliances dryH. Keep appliances dry

I. Don’t use damaged switches, outlets, I. Don’t use damaged switches, outlets, fixtures, extension cordsfixtures, extension cords

J. Follow manufacturer’s instructions for J. Follow manufacturer’s instructions for installation and use of electrical installation and use of electrical equipmentequipment

VI. Service EntranceVI. Service EntranceA.A. Power from Electric companyPower from Electric company

1. Jones-Onslow1. Jones-Onslow2. Progress Energy2. Progress Energy

B. B. TransformerTransformer: drops volts from : drops volts from 25,000 volts to 240 volts25,000 volts to 240 volts

C. C. Service dropService drop: wires etc from : wires etc from transformer to housetransformer to house

D. D. Entrance headEntrance head: weather-proof at : weather-proof at househouse

E.E. Meter Meter: $$$: $$$F.F. Service Entrance Panel (SEP): Service Entrance Panel (SEP): box box

with fuses or breakerswith fuses or breakers

VII. Branch CircuitsVII. Branch Circuits

A.A. Usually begin at Service Entrance Usually begin at Service Entrance Panel (SEP)Panel (SEP)

B.B. 1. 1. Protection devices-Protection devices- stop current stop current flow when max. amps are flow when max. amps are

exceededexceededa. a. FusesFuses- metal strips- metal strips

1). Cartridge1). Cartridge2). Screw in2). Screw in

2. Circuit breakers-reset2. Circuit breakers-resetB. Branch out all over houseB. Branch out all over houseC. Size of circuitC. Size of circuit

1. Only 1 motor 1. Only 1 motor 2. Series of outlets 2. Series of outlets 3. Series of lights3. Series of lights

D. Use correct size wire and fuse or D. Use correct size wire and fuse or breakerbreaker

VIII. Types of CableVIII. Types of CableA. A. Nonmetallic sheathed cable-Nonmetallic sheathed cable-

ROMEXROMEX: copper or aluminum : copper or aluminum wire covered with paper, wire covered with paper, rubber, or vinyl for insulationrubber, or vinyl for insulation

B.B. Armored cable Armored cable: flexible metal : flexible metal sheath with individual wires sheath with individual wires inside. Wires are insulatedinside. Wires are insulated

C. C. ConduitConduit: tubing with : tubing with individually insulated wiresindividually insulated wires

IX. Wire IdentificationIX. Wire IdentificationA. A. Type based on :Type based on :

1. Outer cable (more than one wire) 1. Outer cable (more than one wire) covering- undergroundcovering- underground2. Individual wire covering2. Individual wire covering

a. Plasticsa. Plastics3. Size of wire- 13. Size of wire- 1stst #=gauge 2 #=gauge 2nd nd = # = # of conductorsof conductors

a. 12-2 has two a. 12-2 has two strands of strands of No. 12 wire No. 12 wire (black & (black & white)white)

1). 12-2 w / g same, 1). 12-2 w / g same, with with one green or one green or barebare

b. 12-3 has three strands b. 12-3 has three strands of of No. 12 (black, red, No. 12 (black, red, white)white)

1). 12-3 w/g same, with 1). 12-3 w/g same, with green or baregreen or bare

4. Number of wires- 12-24. Number of wires- 12-2B. Wire type stamped on outer surfaceB. Wire type stamped on outer surface

C. Wire Color codesC. Wire Color codes

1. 1. BlackBlack- load carrier- load carrier

a. Wire carries current to a. Wire carries current to applianceappliance

2. 2. WhiteWhite- neutral- neutral

a. Wires carry current from a. Wires carry current from appliance back to appliance back to sourcesource

3. 3. GreenGreen- ground- ground

a. Ground all metal boxes a. Ground all metal boxes and and appliancesappliances

4. 4. RedRed- load- traveler in 3-way - load- traveler in 3-way switchesswitches

X. Wire Type and SizeX. Wire Type and Size

A. Copper or aluminumA. Copper or aluminum1. Aluminum use one size larger1. Aluminum use one size larger2. Does not handle heat2. Does not handle heat

B. SizesB. Sizes1. Lower gauge number = larger wire1. Lower gauge number = larger wire2. No 14 (14 gauge) = 15 amp circuits 2. No 14 (14 gauge) = 15 amp circuits (125V)(125V)3. No 12 = 20 amps (240 V)3. No 12 = 20 amps (240 V)4. No 10 = 30 amps 4. No 10 = 30 amps 5. No 8 and larger use bundles of wires5. No 8 and larger use bundles of wires6. Current travels on outer surface of wire, 6. Current travels on outer surface of wire, so a bundle of smaller wires can carry so a bundle of smaller wires can carry moremore

C. C. Wire typesWire types (places in house ? ) (places in house ? )

1. 1. Type TType T - dry locations - dry locations

2. 2. Type TWType TW - dry or wet - dry or wet

3. 3. THHNTHHN - dry, high temps - dry, high temps

4. 4. THW and THWNTHW and THWN - wet, high temps - wet, high temps

5. 5. XHHWXHHW - high moisture & heat resistance - high moisture & heat resistance

6. 6. UFUF - - direct burial in soil but not concrete direct burial in soil but not concrete

XI. Voltage DropXI. Voltage Drop

A. Loss of voltage as it travels along a A. Loss of voltage as it travels along a wirewire

1. Lights dim, motors overheat1. Lights dim, motors overheatB. Larger wires have less voltage drop for B. Larger wires have less voltage drop for

a given amount of currenta given amount of currentC. Longer wire = greater problemC. Longer wire = greater problemD. Must increase wire size as distance D. Must increase wire size as distance

increasesincreases

XII. Electric Meter-measures XII. Electric Meter-measures electricity usedelectricity usedA.A. Watts Watts: measure of the : measure of the amount of energy or amount of energy or

workwork that can be done that can be done

B. B. Watt-hourWatt-hour = use of 1 watt for one hour= use of 1 watt for one hour1. 100 watt light bulb for 1 hour - 100 watt-hours1. 100 watt light bulb for 1 hour - 100 watt-hours

C.C. Kilowatt Kilowatt = 1000 watts = 1000 watts

1. Kilowatt-hours: how electricity is sold1. Kilowatt-hours: how electricity is sold

2. Kilowatt-hour = 1000 watts for one hour2. Kilowatt-hour = 1000 watts for one hour

XIII. Calculating electrical useXIII. Calculating electrical useA. Watts=Volts x AmpsA. Watts=Volts x Amps

1. 1. ProblemProblem=What is the watt rating of a 20 amp =What is the watt rating of a 20 amp saw in a 220 V circuit ?saw in a 220 V circuit ?

2. 2. SolutionSolution= Watts = Volts x Amps= Watts = Volts x AmpsWatts= 220 Volts x 20 Amps= 4400Watts= 220 Volts x 20 Amps= 4400

B. Watt- hours = (V x A) x hours of useB. Watt- hours = (V x A) x hours of use1. 1. Problem Problem = How many watts will an electric motor = How many watts will an electric motor that requires 7.5 amps of electricity, and is on a that requires 7.5 amps of electricity, and is on a 120 V circuit for 10 hours?120 V circuit for 10 hours?2. 2. Solution Solution Watt- hours = V x A x hours of useWatt- hours = V x A x hours of use

Watt-hours= 120 V x 7.5 A x 10 Hrs= Watt-hours= 120 V x 7.5 A x 10 Hrs= 90009000

C.C. Kilowatt- hours Kilowatt- hours= watts/1000 x hours of use= watts/1000 x hours of use1. 1. Problem-Problem- An Ag. Shop has 5- 200 watt An Ag. Shop has 5- 200 watt

lights, a 600 watt saw and a lights, a 600 watt saw and a 100 watt 100 watt fan that were used for 5 fan that were used for 5 Hrs. How many Hrs. How many kilowatts were used.kilowatts were used.

2. 2. SolutionSolution- - Kilowatt-hours= watts/1000 x Kilowatt-hours= watts/1000 x hrs hrs usedused

KWH= (KWH= (5x200 watts) + 600 watts +100 watts x 55x200 watts) + 600 watts +100 watts x 5 = 8.5 = 8.5

1000 watts/Kilowatt1000 watts/KilowattD. D. CostCost = KILOWATT-HOURS x Cost / kilowatt –hr. = KILOWATT-HOURS x Cost / kilowatt –hr.

1. . 1. . ProblemProblem = If the local rate for electricity = If the local rate for electricity is is $ .12 per KWH, how much should the $ .12 per KWH, how much should the

electric bill be for 100 KWH ?electric bill be for 100 KWH ?a). a). SolutionSolution- Cost = KWH x Cost/KWH- Cost = KWH x Cost/KWH

Cost = 100 KWH x $ .12/KWH=$ 12.00Cost = 100 KWH x $ .12/KWH=$ 12.00