FUSES

Fuses

• FUSE- contains a thin wire that heats up and melts if too much CURRENT passes through it. (basically what happens when a "fuse blows")
• RATING OF A FUSE- MAXIMUM current that can pass through it without melting the fuse wire.
• Fuse should always be in SERIES WITH the LIVE WIRE between the live wire and appliance. If the fuse blows, the appliance is then cut off from the live wire and so it avoids electric shocks or any other hazards.
• the earth wire protects the user and the fuse protects the appliance and the wiring of the circuit.
• When the live wire is connected to the metal casign its current passes through the Earth wire which is also attached:
  
• The Earth Wire has a LOW RESISTANCE. --> which means current would go up --> blows the FUSE.
  

Fuse Ratings

it must have a correct rating.

• if the rating is too large- the fuse would not blow when it should-and the heating effect of the current could cause appliance/cable on fire.

• --> As current flows, the there is friction between the electrons passing in the current and the conductor.
  
•  if there is more current= more friction= more heat --> fuse would melt.

Fuse Ratings and Calculations

• Domestic appliances are often fitted with a 5A, 3A or 13A fuse.
  

to find a correct rating…