Fuses and earthing

• What is a common problem when dealing with electricity?

  Sudden increases in current, known as surges
• What can cause surges in an electrical circuit?

  Changes in a circuit or faults in the circuit or appliance
• What are the potential dangers of electrical surges?

  They can cause fires or electric shocks
• What safety precautions can help reduce risks associated with electrical surges?

  • Fuses
  • Circuit breakers
  • Earth wires
  • Double insulation
• How do fuses and circuit breakers function similarly?

  Both break the circuit when the current gets too high
• What is a fuse made of?

  A very thin piece of wire connected to the live wire
• What happens to a fuse when there is a surge?

  The fuse wire heats up and melts, breaking the circuit
• What do fuses come in?

  Different ratings depending on the current
• If an appliance normally has a 3 amp current, what fuse rating could you use?

  A 5 amp fuse
• What fuse rating would you use for a 10 amp appliance?


  A 13 amp fuse
• What is a disadvantage of fuses?


  They are permanently broken after a single surge
• How do circuit breakers differ from fuses?

  Circuit breakers consists of an automatic electromagnet which breaks the circuit if the current rises over a certain value. It differs from a fuse as it can be reset and they operate faster
• What happens when a circuit breaker breaks?

  The circuit is turned off
• What is one way surges can cause harm in appliances?

  If the live wire comes loose and touches the casing
• How does earthing prevent electric shocks?

  It creates a safe route/alternative pathway for current to flow through the ground. Earth wires have a very low resistance so when a strong current surges through them, it breaks the fuse and disconnects the appliance.
• What is double insulation in appliances?

  Covering the entire appliance in a plastic casing
• What is the benefit of double insulation?


  It prevents exposed metal parts that can cause electric shocks
• When is an earth wire not needed in an appliance?

  When the appliance has double insulation
• What wires does an appliance with double insulation have?

  Live and neutral wires
• What are the main functions of fuses and circuit breakers?


  • Fuses: Break the circuit permanently when current surges
  • Circuit Breakers: Break the circuit temporarily and can be reset