Evan's Space

Wonders of Physics

Double Insulation

2 Comments

Why some electrical appliances do not need earth wire or they only have 2 pins (live and neutral)? For some 3 pins plug, the earth pin is actually plastic (that means no earth wire). Why?

Double_insulation_01Double_insulation_02Double_insulation_03

Why make the earth pin with plastic since there is no earth wire?
Having the plastic earth pin is to provide convenience for user to plug in the 3-pins. Without the earth pin the plug wouldn’t go into the socket. The earth pin is needed to open a cover inside the socket that stops people from touching the live parts.

(Thanks Bob Barrett for the suggestion to improve the explanation)

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2 thoughts on “Double Insulation

  1. Hi Evan. I love your illustrations. On this post, I would request a small change to the text where it says “Why make the earth pin with plastic since there is no earth wire?”. Please don’t recommend poking sharp objects into mains sockets. It’s never a good idea and, even if you did it, there is no two pin plug that would fit the socket properly.

    Why not say this instead …
    “Why make the earth pin with plastic since there is no earth wire? Without the earth pin the plug wouldn’t go into the socket. The earth pin is needed to open a cover inside the socket that stops people from touching the live parts.”

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