In Singapore, we use the 3-pin wall socket 240 V. In general, it is more convenient if the plug of appliance is 3-pin. But certain appliances we bought online may not be, just like the fan shown in the video below. It has 2 pins, i.e. a live wire and a neutral wire. No earth wire is present as the outer casing is made of electrical insulator, plastic.
Take a look at the video, and you can easily convert the 2=pin to 3-pin plug.
Double-insulated appliances are common around us. The air purifiers in our classroom are one good example.
In these appliances, only two wires are needed, namely Live and Neutral wires. Earth wire is not required as the casing is made of insulator like plastic for this case.
Simply put, electric appliance can be very simple with just a live wire bring in the current and a neutral wire to bring the current out. The appliance can just work like this forever (without the hassle of having earth wire, fuse etc), provided there is no electric fault developed.
Both the earth wire and the fuse are safety features to protect the user and the appliance respectively. Take a look at the video below to understand the rationale.
Recall these notes given:
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