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Chapter 5
Using Electricity in the Home
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Work = force (Newtons) X distance (m)
In order to do work a force must movethrough a distance.
Kinetic energy involves movement or use Potential energy means that it can be used
On Earth we can convert our weight in
kilograms to Newtons by multiplying by 10i.e.. One kilogram becomes 10 N
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Energy = Voltage X Current X
time The units for energy are joules (J)
Power = energy / time
Power = Voltage (v) X Current (I)
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House Hold Energy
Consumption Hydro bills are established by finding
out how many kilowatt hours of
electricity your household has used in agiven time.
1 kWh = kilowatts X time (hours)
1 kWh = 1 000 Watts X 1 hour
1 kWh = 1 000 W X 3 600 seconds
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Reading the Meter always
use the smallest number
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This reading should be 88762
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Efficiency This is a comparison of the amount of
energy obtained as compared to the
amount of energy put into the system
Efficiency = energy output / energy input
To convert it to a percentage just multiplythe answer by 100 %
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House Hold Wiring The wires coming into a house include a black, a
red and a white.
The blackand the redwires are hot
The white wire is neutral leading to a ground
The black is rated as being 120 v from the neutral The red is rated as being 120 v from the neutral
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Electricity Entering Your House
Red = In at 120V
Black = Out at 120VPotential difference = 240V
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Household Wiring is in ParallelWhich connecting wire, A, B, C,
D, or E, will be the first to
become dangerously hot if toomany appliances are turned on?
How can overheating be prevented,
even if all the appliances in the
house are turned on
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Alternating Current Frequency In North America, the current alternates back
and forth in what we call cycles per second
1 cycle/second = 1 Hertz
Electrical frequency in North America = 60 Hz
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The Service Panel Since the service panel has black, red, and
white wires, the total voltage is 120 + 120 =240 volts.
The service panel usually contains circuitbreakers. The breakers have either a red ora black wire attached to them.
The service panel provides electricity for thebranch circuits.
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Usually 15 ampbreaker
30 amps or greater
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Powerful Devices
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The Neutral Wire (White) The neutral wire is the ground
Grounds protect us from electrocution
Service Panel has a ground wire
3 prong plug the circular, bottom holeleads to the ground buried outside.
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The Neutral Wire (White) The neutral wire is _____________
Grounds protect us from __________ Service Panel has a ______________
3 prong plug the circular, bottom hole
_________________________________.
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Three Prong Plug
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Circuit Breakers Circuit breakers open the circuit when a
current in a house wire exceeds the ratedcurrent for that circuit.
The circuit breaker protects people frombeing electrocuted to death and protects usfrom burning down the house.
Circuit overloads cause the generation ofheat.
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Circuit breakers - Details Ordinary breakers are rated as 15 amps.
There are bigger breakers provided for suchcircuits that require 240 volts e.g.. Dryersand water heaters.
Instead of circuit breakers some electricaldevices have fuses. Often electric stoveshave fuses.
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Fuses are Older than Circuit of
Breakers
When ribbon carries too much current,
it melts, interrupting the current.
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GFCI Ground Fault Circuit
Interrupter1. Detects current
differences in the neutraland hot wire
2. Should be same
3. If not, the internalbreaker goes immediately
4. Can reset
5. Use near water sourceswhere safety is concern
6. Bathroom, outdoor outlets
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House Hold Wiring
House hold circuits are 120 volts and are alternatingcurrent. Appliances are usually connected in parallel.
The circuits are polarized. That is, the black wire isconnected in a certain way and the neutral wire isconnected in a certain way.
Polarized plugs reduce the risk of an electrical shockby forcing electricity to flow in one general direction
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Types of PlugsUsed in the
Home
Drier Plug orStove Plug
(Ground)
Lamp Plug orHair Dryer
(Polarized)
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Three Prong Plug
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Three pronged plug The round prong is the ground
The longer hole is connected to the white
wire (neutral). We need this wire tocomplete the circuit.
The shorter hole is connected to the black
wire.(hot120 Volts)
The grounded plug is safer than a twopronged plug.
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Grounding the Current The service panel is connected to a long
metal stake that buried outside the house.
If a person is electrocuted most of thecurrent will go to ground.
In much older houses the wiring isgrounded on the copper water pipes.
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Ground Wire
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Improperly Grounded Appliance with Short
One milliampere: tingling sensationTen milliamperes: nerves and muscles overloaded200 milliamperes: potentially fatal; heart fibrillation500 -1000 milliamperes: not necessarily fatal; heart willrestart -- One ampere or more: burn alive
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Grounded Appliance
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Ground Plugs Prevent You frombecoming the Shortest, Easiest Path to
the Ground!!
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Avoid! Or.. Thou Shalt Not!
1. Frayed electrical wires
2. Octopus outlets
3. Water and electrical wires
4. Plug receptacles to protect smallchildren
5. Over loading electrical circuits