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Electrical Safety

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Electric current will always take the path of least resistance. ... Because there is so little resistance, there will be a massive surge in current. ... – PowerPoint PPT presentation

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Title: Electrical Safety


1
Electrical Safety
2
Electrical Safety
  • Electric current will always take the path of
    least resistance.
  • This is usually the quickest way to the Earth.
  • Even small voltages can kill.

3
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4
Electrical Safety
  • Read the leaflet on Electrical Safety.
  • List what you think are the 10 most important
    rules on electrical safety.

5
Electrical Safety
  • There are three wires in a plug.
  • The brown wire carries the live current.
  • The yellow and green wire leads to the Earth.
  • The blue wire completes the circuit.

6
Electrical Safety
  • Everyone should be able to wire a plug!
  • Take a plug and correctly wire it.
  • Do not attempt to place the plug in a socket.
  • Get the teacher to check your wiring

7
Electrical Safety
  • If the live wire touches the metal case of an
    appliance
  • The current will flow through the Earth wire to
    the Earth
  • Because there is so little resistance, there will
    be a massive surge in current.
  • This will melt the fuse wire.
  • The current supply is thus cut off.

8
Electrical Safety
  • Read the information on p110 of Further Science
    on double insulation.
  • Copy the symbol for double insulation.
  • Make a note to explain what it means

9
Fuses
  • Page 110 of Further Science

10
Fuses
  • This is the symbol for a fuse.

11
Fuses
  • If too much current flows in a circuit the fuse
    will melt and break the circuit.
  • The fuse protects
  • The wiring
  • The appliance
  • The user

12
Fuses
  • Different appliances require different sized
    fuses, e.g.
  • A cooker, 30 Amp
  • A lighting circuit, 5A
  • A table lamp, 3A
  • An electric kettle, 13A

13
Fuses
  • Fitting the wrong sized fuse is one of the most
    frequent causes of fire in the home.
  • Many people die in these fires each year.

14
Fuses
  • In modern houses and buildings fuses have tended
    to be replaced by residual circuit breakers (RCB)

15
Residual Circuit Breakers
  • Page 111
  • Further Science

16
Residual Circuit Breakers
  • Read p111 of Further Science
  • Make a set of bullet points on what RCBs are and
    how they work.
  • This material is examined on Higher tier papers
    and questions only.
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