ElectricityElectricityA Review and then some…A Review and then some…

Ampere – rate of electrical flow (volume of Ampere – rate of electrical flow (volume of electricity flowing)electricity flowing)

““Amps”Amps”

Voltage or electromagnetic forceVoltage or electromagnetic force

– – a measure of electrical pressure a measure of electrical pressure

ResistanceResistance

The opposition to the flow of electrons The opposition to the flow of electrons through a conductor – measured in Ohmsthrough a conductor – measured in Ohms

WattWatt

Refers to the amount of power derived from Refers to the amount of power derived from a device or the rate of doing worka device or the rate of doing work

Example – 100 watt light bulbExample – 100 watt light bulb

1500 watt blow dryer1500 watt blow dryer

Kilowatt = 1000 wattsKilowatt = 1000 watts

Kilo-watt hourKilo-watt hour

Electricity is sold by the kilowatt hour Electricity is sold by the kilowatt hour

(gasoline is sold by the gallon)(gasoline is sold by the gallon)

Using 1000 (kilo) watts for one hour is a Using 1000 (kilo) watts for one hour is a KWHKWH

Watts and HorsepowerWatts and Horsepower

746 watts = one horsepower746 watts = one horsepower

Watts = Volts x AmpsWatts = Volts x Amps

Sometime referred to as the West Virginia Sometime referred to as the West Virginia Formula.Formula.

The amount of work that can be done in a The amount of work that can be done in a circuit is equal to the voltage in the circuit circuit is equal to the voltage in the circuit times the ampstimes the amps

WVA AnalagyWVA Analagy

You can wash your car (do work) faster is You can wash your car (do work) faster is you have a large hose with lots of you have a large hose with lots of pressure.pressure.

A large hose will allow for greater flow of A large hose will allow for greater flow of water (flow = amps)water (flow = amps)

Pressure would be = voltage (force) Pressure would be = voltage (force)

Types of Electrical CurrentTypes of Electrical Current

Alternating CurrentAlternating Current The current that flows in cycles, traveling first The current that flows in cycles, traveling first

One Direction (no pun intended), then One Direction (no pun intended), then reversing to the other direction, and so on.reversing to the other direction, and so on.

Our AC is 60 cycles per second, also called Our AC is 60 cycles per second, also called 60 Hertz (Hz).60 Hertz (Hz). Current that changes direction 120 times per Current that changes direction 120 times per

second.second.

Alternating Current ExamplesAlternating Current Examples To the window… from the wall…To the window… from the wall…

Direct CurrentDirect Current The current in which electrons flow only in The current in which electrons flow only in

One Direction (again, no pun intended!).One Direction (again, no pun intended!). Electrons flow from the negative terminal to Electrons flow from the negative terminal to

the positive terminal in an electrical circuit.the positive terminal in an electrical circuit. Fixed polarity- direction of flow.Fixed polarity- direction of flow.

Direct Current Examples…Direct Current Examples… From batteries…From batteries…

CircuitCircuitA controlled path for electricity to flow beginning at the A controlled path for electricity to flow beginning at the

source (usually a breaker), traveling to the consumer source (usually a breaker), traveling to the consumer (ex. light) and back to the source.(ex. light) and back to the source.

The colored wire goes to the consumer and the white The colored wire goes to the consumer and the white wire “comes back” to complete the circuitwire “comes back” to complete the circuit

Unless a complete circuit is made – the devices will not Unless a complete circuit is made – the devices will not workwork

Breakers and switches are usually used to control the Breakers and switches are usually used to control the flowflow

National Electrical CodeNational Electrical Code

The benchmark for safe electrical design, The benchmark for safe electrical design, installation, and inspection to protect people installation, and inspection to protect people and property from electrical hazards.and property from electrical hazards.

The NEC addresses the installation of electrical The NEC addresses the installation of electrical conductors, equipment, and raceways.conductors, equipment, and raceways.

Updated and published every three years.Updated and published every three years.

ConductorConductor

Substance that will allow for the flow of Substance that will allow for the flow of electricityelectricity

Most common: copper, aluminumMost common: copper, aluminum

Best Conductor: GoldBest Conductor: Gold

InsulatorInsulator

Substance that does not allow for the flow of Substance that does not allow for the flow of electricityelectricity

Plastic, rubberPlastic, rubber

Parallel CircuitParallel Circuit

A circuit that has more than one way that A circuit that has more than one way that electricity can flow.electricity can flow.

Most common type of circuitMost common type of circuit

Series CircuitSeries Circuit

Has only one pathway for electricity to Has only one pathway for electricity to follow. If there is more than one device in follow. If there is more than one device in the circuit, the electricity must flow through the circuit, the electricity must flow through one device and continue on to the next one device and continue on to the next device. Not normally used in houses.device. Not normally used in houses.

Christmas lights are sometimes wired in Christmas lights are sometimes wired in series. That is why if one bulb goes out series. That is why if one bulb goes out the whole line goes outthe whole line goes out

W = V*AW = V*A

A device (such as a light) hooked to a 120 A device (such as a light) hooked to a 120 volt circuit that is pulling 5 amps would be volt circuit that is pulling 5 amps would be using how many watts?using how many watts?

W = V * AW = V * A

Also means that:Also means that:

V = W / A (watts divided by amps)V = W / A (watts divided by amps)

A = W / V (watts divided by volts)A = W / V (watts divided by volts)