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Electrical Safety. 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. Electrical Safety. Read the leaflet on 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.
Electrical Safety • Read the leaflet on Electrical Safety. • List what you think are the 10 most important “rules” on electrical safety.
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.
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
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.
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
Fuses Page 110 of Further Science
Fuses • This is the symbol for a fuse.
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
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
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.
Fuses • In modern houses and buildings fuses have tended to be replaced by residual circuit breakers (RCB)
Residual Circuit Breakers Page 111 Further Science
Residual Circuit Breakers • Read p111 of Further Science • Make a set of bullet points on what RCB’s are and how they work. • This material is examined on Higher tier papers and questions only.