Electrical Safety

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Electrical Safety
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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.

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Electrical Safety

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

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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.

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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

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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.

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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

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Fuses

• Page 110 of Further Science

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Fuses

• This is the symbol for a fuse.

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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

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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

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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.

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Fuses

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

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Residual Circuit Breakers

• Page 111
• Further Science

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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.