What does 3-pole mean?

What does 3-pole mean?

3-pole means that the devices‘ plug is earthed and that it normally has three pins, of which two are used to transfer the current and one is used as personal protection.

Due to the predominance of more powerful devices in the 1930s (normally around 500 watts) the consequences of possible electric shock became a real hazard. In order to guard against this, an earth connection had to be fitted to the 2-pole plugs for these devices. In all plug types, the earth connection was fitted as a 3rd pin. The exception is the Schuko plug in which the earth connection is located on the side of the plug and made of metal contact surfaces.

Removal of the earth connection is not a good idea, since it is one of the major safety features of a product. In the case of all 3-pole plugs which meet the legal standards, this earth connection has been constructed as a leading connection, which means that the earth connection closes the contact before the other two pins make power contact.

In most countries in the world, the 2-pole mains sockets have been replaced with 3-pole earthed sockets which can accept both 2-pole and 3-pole plugs.


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