Electricity

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Electricity
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Menu

• AC DC

• Household Plugs Fuses
• Power Fuses

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AC DC
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Alternating Current (AC)
Voltage
The current changes direction 50 times every
second (frequency 50Hz)
Time
AC is easier to generate than DC
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Direct Current (DC)
The current only flows in one direction
Voltage
Time
If the cell is reversed the current flows in the
opposite direction
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Household Plugs Fuses
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Wiring a plug
Earth Wire
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Fuse
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Neutral Wire
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Live wire
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Cable grip
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Cable
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Errors in Wiring Plugs

1. Bare wires showing
2. Proper fuse not installed
3. Earth Wire not connected
4. Live Neutral wrong way round
5. Cable Grip loose

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Dangerous Practices With Mains Electricity

1. Broken Plugs Frayed Cables
2. Plugs Cables near water
3. Overloaded sockets
4. Wet hands whilst using electricity

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The Earth Wire
Earth wires are always used in appliances with a
metal case. If a fault develops in the
appliance causing the live wire to touch the
case, there is a surge in the current down the
earth wire. This causes the fuse to blow.
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Live Neutral
The Live wire alternates between high positive
and high negative voltage with an average of
about 230V
The neutral wire is always at 0V. Electricity
normally flows in and out of the live and neutral
wires only
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Fuses
Symbol
Car fuses
A Fuse is a deliberate weak spot in a circuit
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How Does a Fuse Work?
Fuses are designed for safety. If a fault
develops causing the live and neutral (or earth)
wire to cross, a large current flows through the
fuse and causes it to melt. This breaks the
circuit and protects the appliance and user.
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Complete the descriptions..
Fuse A deliberate weak spot. Melts and breaks the circuit with too much current
Earth Wire
Neutral Wire
Live Wire
Cable Grip
Casing
Brass Pins
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Power Fuses
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Power, Current Voltage
Power is the rate of doing work. The amount of
power being used in an electrical circuit is
given by
Power voltage x current (W) (V)
(A)
The unit of power is the watt (W)
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Power and Fuses
Complete the following table
Appliance Power Rating (W) Voltage (V) Current (A) Fuse Required (3, 5 or 13A)
Toaster 950 230
Electric Fan Heater 2200 230
Hairdryer 330 230
Floor Cleaner 1050 230
Computer 200 230
HiFi 80 230
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