Post on 19-Dec-2015
Principles of ElectricityPrinciples of Electricity
Electricity is a form of energy that can Electricity is a form of energy that can produce light, heat, magnetism, chemical produce light, heat, magnetism, chemical changeschanges
Resistance: tendency of a material to Resistance: tendency of a material to prevent electrical flowprevent electrical flow
Conductor: if electricity flows easilyConductor: if electricity flows easily Insulator: material that provides great Insulator: material that provides great
resistanceresistance
Amps, Volts, WattsAmps, Volts, Watts
Amperes: measure of the rate of flow of Amperes: measure of the rate of flow of electricity in a conductorelectricity in a conductor
Volts: measure of electrical pressureVolts: measure of electrical pressure Watts: measure of the amount of energy Watts: measure of the amount of energy
or work that can be doneor work that can be done Ohms: measure of electrical resistance Ohms: measure of electrical resistance
to flowto flow
Ohm’s LawOhm’s Law
Ohm = ROhm = R Volts = EVolts = E Amps = IAmps = I Ohm’s Law: E = IROhm’s Law: E = IR
I=E/R I=E/R
R=E/IR=E/I
Electrical SafetyElectrical Safety Shock and FireShock and Fire Never disconnect any safety deviceNever disconnect any safety device Don’t touch electrical items with wet hands Don’t touch electrical items with wet hands
or feetor feet Don’t remove ground plug prongDon’t remove ground plug prong Use GFI in wet areasUse GFI in wet areas Discontinue use of extension cord that feels Discontinue use of extension cord that feels
warmwarm Don’t put extension cords under carpetDon’t put extension cords under carpet
Electrical SafetyElectrical Safety Install wiring according to NECInstall wiring according to NEC
Blown fuse or breaker, determine causeBlown fuse or breaker, determine cause
Don’t replace fuse with larger fuseDon’t replace fuse with larger fuse
Electrical SafetyElectrical Safety Don’t leave heat producing appliances Don’t leave heat producing appliances
unattendedunattended Heaters & lamps away from Heaters & lamps away from
combustiblescombustibles Don’t remove back of TV (30,000v when Don’t remove back of TV (30,000v when
off)off) Electric motors lubricated, free of grease Electric motors lubricated, free of grease
etcetc
Electrical SafetyElectrical Safety
Keep appliances dryKeep appliances dry Don’t use damaged switches, outlets, Don’t use damaged switches, outlets,
fixtures, extension cordsfixtures, extension cords Follow manufacturer’s instructions for Follow manufacturer’s instructions for
installation and use of electrical installation and use of electrical equipmentequipment
Power Generation PlantsPower Generation Plants Power PlantsPower Plants
Burn coal or wood to produce Burn coal or wood to produce
Wind FarmsWind Farms Use wind turbines to generate powerUse wind turbines to generate power
Solar PanelsSolar Panels Placed on roofs to captrure solar power from the sunPlaced on roofs to captrure solar power from the sun
Hydro PlantsHydro Plants Use flowing water from lakes and rivers to generate Use flowing water from lakes and rivers to generate
powerpower
Service EntranceService Entrance Power from power companyPower from power company Transformer: drops volts from 25,000 volts Transformer: drops volts from 25,000 volts
to 240 voltsto 240 volts Service drop: wires etc from transformer to Service drop: wires etc from transformer to
househouse Entrance head: weather-proof at houseEntrance head: weather-proof at house Meter: $$$Meter: $$$ Service Entrance Panel (SEP): box with Service Entrance Panel (SEP): box with
fuses or breakersfuses or breakers
Electric MeterElectric Meter
Kilowatthours: how electricity is soldKilowatthours: how electricity is sold Kilo = 1000Kilo = 1000 Watthour = use of 1 watt for one hourWatthour = use of 1 watt for one hour
100 watt light bulb for 1 hour - 100 100 watt light bulb for 1 hour - 100 watthourswatthours
Kilowatthour = 1000 watts for one hourKilowatthour = 1000 watts for one hour
Branch CircuitsBranch Circuits
usually begin at SEPusually begin at SEP branch out into a variety of placesbranch out into a variety of places only 1 motor or;only 1 motor or; series of outlets or;series of outlets or; series of lightsseries of lights use correct size wire and fuse or use correct size wire and fuse or
breakerbreaker
Types of CableTypes of Cable
Nonmetallic sheathed cable: copper or Nonmetallic sheathed cable: copper or alluminum wire covered with paper, alluminum wire covered with paper, rubber, or vinyl for insulationrubber, or vinyl for insulation
Armored cable: flexible metal sheath Armored cable: flexible metal sheath with individual wires inside. Wires are with individual wires inside. Wires are insulatedinsulated
Conduit: tubing with individually Conduit: tubing with individually insulated wiresinsulated wires
Wire Type and SizeWire Type and Size coppercopper No 14 (14 gauge) = 15 amp circuitsNo 14 (14 gauge) = 15 amp circuits No 12 = 20 ampsNo 12 = 20 amps No 10 = 30 ampsNo 10 = 30 amps aluminum use one size largeraluminum use one size larger lower gauge number = larger wirelower gauge number = larger wire No 8 and larger use bundles of wiresNo 8 and larger use bundles of wires current travels on outer surface of wire, so a current travels on outer surface of wire, so a
bundle of smaller wires can carry morebundle of smaller wires can carry more
Voltage DropVoltage Drop
loss of voltage as it travels along a wireloss of voltage as it travels along a wire lights dim, motors overheatlights dim, motors overheat larger wires have less voltage drop for a larger wires have less voltage drop for a
given amount of currentgiven amount of current longer wire = greater problemlonger wire = greater problem must increase wire size as distance must increase wire size as distance
increasesincreases
Wire IdentificationWire Identification
Type of outer covering, individual wire Type of outer covering, individual wire covering, cable construction, number of covering, cable construction, number of wireswires
Wire type stamped on outer surfaceWire type stamped on outer surface
Wire TypesWire Types
Type T - dry locationsType T - dry locations Type TW - dry or wetType TW - dry or wet THHN - dry, high tempsTHHN - dry, high temps THW and THWN - wet, high tempsTHW and THWN - wet, high temps XHHW - high moisture & heat resistanceXHHW - high moisture & heat resistance UF - direct burial in soil but not concreteUF - direct burial in soil but not concrete
Wire IdentificationWire Identification
Color coded: black, red, & blue = Color coded: black, red, & blue = positive or hot wires which carry current positive or hot wires which carry current to appliancesto appliances
White = neutral wires carry current from White = neutral wires carry current from appliance back to sourceappliance back to source
Green or Bare = ground all metal boxes Green or Bare = ground all metal boxes and appliancesand appliances
Wire IdentificationWire Identification
Wire Size: 12-2 has two strands of No. Wire Size: 12-2 has two strands of No. 12 wire (black & white)12 wire (black & white)
12-2 w/g same, with one green or bare12-2 w/g same, with one green or bare 12-3 has three strands of No. 12 (black, 12-3 has three strands of No. 12 (black,
red, white)red, white) 12-3 w/g same, with green or bare12-3 w/g same, with green or bare
Energy AuditEnergy Audit
Looking at your home and identifying Looking at your home and identifying ways to save on electricity. ways to save on electricity. Insulation: R value in Texas is R-30Insulation: R value in Texas is R-30 Sealing doors and windowsSealing doors and windows Temperature adjustments during winter Temperature adjustments during winter
and summerand summer Turning off lights and appliances Turning off lights and appliances