Plug & Socket & Cable

So-called industrial plugs and sockets are known, i.e. with cylindrical body with three or more contacts, female holes or male cylindrical terminals, arranged in a generally polygonal configuration and in different positions according to the sector of use.
Said plugs and sockets are provided with safety devices, covers to protect the female contacts, and groove or external longitudinal lug which acts as a key for correct coupling between the male and female elements.
The electrical contacts of said plugs and sockets have a different diameter, i.e. the phase and neutral have the same diameter, but the earth has a larger diameter. The contacts are arranged in a polygon configuration, in which the earth constitutes the vertex.