plugs

[passer_by]

why is it that some appliances have three pin plugs while some have two pin plugs

[KebabMeister]

I'm not an electrician but it might have something to do with the 2 pin plug item being insulated in plastic and therefore giving a low probability of electric shock if it was faulty (where the earth would come in use if it wasn't insulated in plastic). 

[ugly_bob]

The third pin is Earth, which is not always used in European connections. 2-pin UK appliances such as razors don't necessarily need an earth because they are very low current. Similarly, there are 2 different sized eurpoean plugs, the bigger of which doe contain an external earth connection through the socket and is used for higher current appliances

[KebabMeister]

As ugly_bob mentions, the larger Euro plug has two earth connections - either side of the plug in a groove.  This is in addition to the 2 pins.

I quite like the Euro plugs, especially the extension leads because they have a selection of large and small plug connections - the small obviously take up very little room.