Lecture Notes: Understanding Electrical Wires in Plugs and Cables

Main Supply and Electrical Wire Basics

• Electricity in the UK:

  • Supplied by the National Grid.
  • Known as "main supply."
  • Characteristics:
    • Alternating current (AC) at 230 volts.
    • Frequency: 50 hertz.

• Connecting Electrical Appliances:

  • Use of a three-core cable:
    • Consists of three wires: live wire, neutral wire, and earth wire.
    • Wires are made of copper (good conductor).
    • Coated in insulating plastic for safety.

Identifying and Understanding the Wires

• Live Wire:

  • Color: Brown.
  • Function: Provides alternating potential difference (~230 volts) from the main supply.

• Neutral Wire:

  • Color: Blue.
  • Function: Completes the circuit by carrying away current.
  • Potential difference: 0 volts.

• Earth Wire:

  • Color: Striped green and yellow.
  • Function: Safety mechanism; prevents appliance casing from becoming live.
  • Normally carries no current and has a potential difference of 0 volts.

Safety and Risks

• Electric Shock Risk:

  • Occurs due to the potential difference between the live wire and neutral/earth wires (0 volts vs. 230 volts).
  • Humans also have a potential difference of 0 volts:
    • Touching the live wire causes large current flow through the body, leading to electric shock.

• Precautions:

  • Do not touch plug sockets, even if switched off.
  • Live wire can still pose a risk due to its potential difference.

Conclusion

• Importance of understanding electrical wiring for safety.
• Reminder: Do not engage with electrical components carelessly.

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