O Levels Physics (5054)•5054/12/M/J/21
Explanation
Double insulation eliminates need for earth connection
Steps:
- Double insulation means the device has two layers of insulation, making it safe without grounding.
- Such devices use a two-core cable (live and neutral) instead of three-core with earth.
- A three-pin plug is used, but the earth pin remains unconnected to the cable's earth wire.
- The fuse protects the live wire, while live and neutral pins connect to the cable.
Why A is correct:
- Double insulation (per electrical safety standards) removes the need for an earth wire, so the earth pin is not connected.
Why the others are wrong:
- B: Fuse is wired into the live conductor for overcurrent protection.
- C: Live pin connects to the cable's live wire to supply power.
- D: Neutral pin connects to the cable's neutral wire to return current.
Final answer: A
Topic: Electrical safety
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