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Mains Plug Wiring:

Mains Plug Wiring:. Safety Features: a) the fuse (“blows”) with current overload. Safety Features of the mains plug. Electrical Cable consists of three “double insulated” copper leads.

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Mains Plug Wiring:

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  1. Mains Plug Wiring: Safety Features: a) the fuse (“blows”) with current overload

  2. Safety Features of the mains plug

  3. Electrical Cable consists of three “double insulated” copper leads. This insulation is provided by the OUTER cable made of PVC and the inner plastic “SLEAVES” which are colour coded. The cable itself is made of copper wire which is flexible and has very low resistance. As we will see the most dangerous wire is the brown “Live Wire” The neutral wire is essential to complete the circuit. The earth wire is a safety device which does not carry a current in normal circumstances LIVE WIRE NEUTRAL WIRE EARTH WIRE

  4. The mains a.c. circuit

  5. The mains a.c. circuit

  6. The mains a.c. circuit

  7. The mains a.c. circuit The electric current is pushed back and forth 50 times per second. So the p.d has to change 50 times a second This is done by keeping the neutral lead at 0V and changing the potential applied to theLIVE Wire smoothly from a high positive potential to a high negative potential. The potential difference averages out at 230V

  8. LIVE WIRE +300V p.d./V Time/s -300V p.d./V Time/s NEUTRAL WIRE

  9. Any Appliance With a METAL Case Must Be Earthed Earth connection Metal Case

  10. Frayed Wire Without Earth Connection Metal Case Case at 230V Without an earth connection there will be a high potential difference between the case and earth. The current can move to earth though a person who touches the case Earth at 0V

  11. Metal Case Frayed Wire The large current flowing from live to earth now blows the fuse in the mains plug As soon as the case becomes live current follows the easy route to the ground provided by the earth lead. Large conductor buried in the ground

  12. The Earth Lead This is an earth lead attached to a large copper pipe buried in the ground. Many old electric showers were earthed this way. It is not allowed now because plumbers have started to use plastic pipes.

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