Safety devices
1 mark · EasyWhy do modern appliances with plastic casings not require an earth wire?
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Plastic is an insulator so the casing cannot become live or give a shock.
Also accept: It is double-insulated; The casing is not conductive
Common mistakes: Earth wire is always needed
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Marking points
B1 · 1 mark · Mentions plastic's insulating property or non-conductivity as reason no earth needed.
Worked solution
Because plastic is an insulator and cannot conduct electricity, so cannot give a shock if touched.